Winter Ops Webinars: Winter Weather Outlook for 2020/2021

NE LTAP Author

12/07/2020 Added

6 Plays

Description

Al Dutcher, Nebraska Extension Agricultural Climatologist, joins us to share his outlook for 2020-21's winter weather including potential ice and snow events.

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[00:00:01.407]Here I am.
[00:00:03.020]Well, I guess welcome to Nebraska Road Professionals.
[00:00:10.090]Welcome to the first in our series of Winter Ops Webinars.
[00:00:16.130]This first one that we have for you today is a good one.
[00:00:18.550]We have Al Dutcher from the Ag.
[00:00:21.830]He's an Ag extension climatologist here at UNL,
[00:00:25.850]and he is gonna talk with us today
[00:00:29.450]about what he thinks our weather patterns
[00:00:31.370]may look like this winter.
[00:00:33.680]And it's a beautiful day out there today.
[00:00:35.590]It's a great day to talk about winter weather, right?
[00:00:39.926]A little bit about Al.
[00:00:42.760]He has a Bachelor's Degree in Meteorology,
[00:00:45.990]also Masters in Ag Climatology.
[00:00:49.580]He was our state climatologist in Nebraska
[00:00:52.320]from 1991 to 2016.
[00:00:56.270]So 25 years doing that.
[00:01:01.430]And his current position here with extension
[00:01:04.350]he is actively involved in Ag weather
[00:01:09.140]and climate risk analysis,
[00:01:12.330]also historical climate trend analysis.
[00:01:15.450]Some short and long-term weather forecasting,
[00:01:19.610]and then some climate product development
[00:01:21.730]including things like soil, moisture monitoring,
[00:01:26.140]irrigation scheduling products, thermal tracking of crop
[00:01:30.410]and insect development, and cattle comfort indices.
[00:01:36.387]Yeah, that was a new one for me.
[00:01:38.870]Maybe we need to get him to develop
[00:01:40.250]the motor greater comfort indices.
[00:01:42.564](laughing)
[00:01:44.580]Interactive climate trends
[00:01:46.020]and also interactive climate normals atlas development.
[00:01:50.780]So we're real happy to have Al with us today
[00:01:53.750]and I think we'll turn it over to you Al.
[00:01:57.610]All right.
[00:01:58.894]Well, thank you very much for allowing me to speak,
[00:02:02.020]and hopefully everybody can hear me.
[00:02:06.670]I almost get lairy about doing these types of forecasts,
[00:02:09.620]especially since this the first one of the fall
[00:02:12.370]going into the winter.
[00:02:13.960]So you're the guinea pigs, so to speak.
[00:02:16.430]I'm either gonna be a zero or a hero
[00:02:18.540]based on what I'm gonna put out there,
[00:02:20.860]but I really haven't altered my forecast much
[00:02:23.070]from the time that I put out my thoughts
[00:02:26.840]in terms of the official pointer forecast
[00:02:30.923]put out by the Climate Prediction Center.
[00:02:33.820]And then we also put some information out for
[00:02:38.447]"Nebraska Cattlemen" magazine
[00:02:40.000]and that should be in this month's issue
[00:02:42.200]coming up the December issue on the forecast.
[00:02:45.070]So I had a couple of months to look at this.
[00:02:48.970]Temperatures have not exactly played into the way
[00:02:51.970]that I think things have should be going.
[00:02:54.860]But this is Nebraska,
[00:02:55.897]and we know that one week of 80 degree weather
[00:02:59.190]might mean that it will be sub-zero next week,
[00:03:01.320]and I think we've got a good example of this
[00:03:02.920]back in October, when we went to 14 below zero at Alliance,
[00:03:08.440]and three days later we were up in the mid 80s
[00:03:10.600]in central Nebraska, so it is Nebraska.
[00:03:14.430]What I will say is generally a lot of folks
[00:03:17.400]would think that, well,
[00:03:18.900]if the trend that established the fall is pretty consistent
[00:03:22.160]we'll probably see those types of trends in the winter.
[00:03:23.840]And I'm here to say that
[00:03:25.310]based on all the statistical analysis
[00:03:26.640]that we've been able to do on seasonal,
[00:03:28.420]one season to the next season,
[00:03:29.730]there's a very, very poor correlation.
[00:03:31.750]So just because what you see in the fall
[00:03:33.900]does not mean what you're gonna expect to see in the winter.
[00:03:35.850]However, as a meteorologist climatologist
[00:03:38.620]what I do look for is some significance
[00:03:41.630]in terms of the way the jet stream behaves
[00:03:45.100]as a lead to what we might possibly see
[00:03:47.610]as we go into the winter.
[00:03:48.540]Meaning that if we start to see some really strong anomalies
[00:03:51.950]in terms of intense low pressure systems,
[00:03:55.770]we project that forward.
[00:03:57.540]What does that really mean in the winter time?
[00:03:59.030]And what I will say this safely is that
[00:04:00.880]if you looked at the two major events
[00:04:02.340]that really brought in some Arctic air into our region
[00:04:05.380]the first one in September and the second one
[00:04:08.350]the third week of October,
[00:04:09.610]we essentially were running anywhere
[00:04:12.310]from 20 to 40 degrees below normal
[00:04:14.540]from Montana all the way down to the Texas panhandle.
[00:04:16.810]To put that in perspective in simple terms,
[00:04:19.560]here in Lincoln, Nebraska in the middle of January,
[00:04:22.290]that kinda departures mean that we'd be looking
[00:04:23.990]at high temperatures of anywhere from zero to -10 degrees
[00:04:28.270]and low temperatures essentially in the 25 to 35 degree
[00:04:32.100]below zero range.
[00:04:33.190]So those anomalous types of patterns is what scares me
[00:04:37.030]more than anything else going into this winter
[00:04:38.650]because we do know that we've seen two of them.
[00:04:41.000]And typically because we are in a La Nina
[00:04:43.210]we have a greater tendency for these Arctic intrusions.
[00:04:45.860]In fact, typically we will see average
[00:04:48.010]around three Arctic intrusions
[00:04:49.760]defined by a 20 degree drop in temperature
[00:04:51.770]lasting more than three days during the winter.
[00:04:54.730]During La Ninas, that bumps up to in the area of five to six
[00:04:58.400]depending on location in the state.
[00:04:59.790]So we've already had two of these
[00:05:01.010]and we're not even into the winter period.
[00:05:02.530]So from my emphasis that's where I expect to see
[00:05:05.410]some significant issues as we go forward in time.
[00:05:08.480]So let me share the screen here
[00:05:09.890]and we'll go ahead into this talk
[00:05:11.960]and kinda give you an idea of what I am looking at
[00:05:15.330]and let's get here from the beginning.
[00:05:19.700]So here's all the pertinent information.
[00:05:21.160]If you wanna contact me, feel free to send me an email.
[00:05:24.280]I can expand a little bit farther
[00:05:25.590]if you have any additional questions to follow up
[00:05:27.420]in terms of this talk.
[00:05:28.470]But when I look at criteria,
[00:05:31.470]first and foremost, I look at the ENSO phase
[00:05:33.630]and all of that means is the El Nino Southern oscillation.
[00:05:35.780]That's where we define the La Nina and El Nino events
[00:05:38.412]in the equatorial Pacific.
[00:05:40.050]They had the highest correlation
[00:05:41.940]in terms of forecasting probability
[00:05:43.730]of any of the things that we look as meteorologists.
[00:05:46.880]And in fact, there are areas of the globe
[00:05:48.760]where we have better than a 70% correlation.
[00:05:51.060]I'll show you those in a few seconds.
[00:05:53.540]There's two things that do impact our winter weather
[00:05:56.720]outside a La Nina.
[00:05:57.810]If that's not La Nina or El Nino
[00:05:59.800]those are not in play,
[00:06:01.530]and that one is a North Atlantic Oscillation
[00:06:03.930]and essentially think of it this way.
[00:06:05.450]When we hear that phase and North Atlantic Oscillation
[00:06:07.570]is in its cold phase,
[00:06:09.180]it just means that a blocking high pressure
[00:06:10.830]is sitting up over the North Atlantic.
[00:06:12.910]And so the troughs in the Eastern United States
[00:06:14.680]cannot move anywhere, they are kind of blocked,
[00:06:16.830]and so they dig deeper.
[00:06:18.540]And you've heard that if you heard the terms in the press
[00:06:21.220]a Polar Express, Arctic surge,
[00:06:24.660]that's generally what we're looking at
[00:06:26.200]is that walking high pressure in the North Atlantic.
[00:06:28.450]At the same time the Gulf of Alaska is important
[00:06:31.320]because we're in the Westerlies here in North America.
[00:06:34.250]So we look up the Gulf of Alaska for pending storm systems
[00:06:37.390]that may come into our region.
[00:06:38.307]And depending on the location on that low pressure system
[00:06:41.350]we're really determine where that energy
[00:06:42.850]comes into the United States
[00:06:44.400]or to the North of the United States,
[00:06:46.070]and where the Ridge downstream from it will play.
[00:06:48.770]And the further downstream the ridge is
[00:06:50.600]the nicer the weather is.
[00:06:52.040]So we can be thankful at this point in time
[00:06:54.390]that the low pressure system in the Gulf of Alaska right now
[00:06:56.980]is in a position that is pushing that ridge
[00:06:59.070]well far to the East.
[00:07:00.920]The result is we're getting above normal temperatures.
[00:07:04.410]The other thing that we also look at,
[00:07:05.658]at least I look at,
[00:07:06.830]is the snow cover conditions,
[00:07:08.210]and I've been paying pretty particular attention to this
[00:07:10.470]because during La Nina years,
[00:07:12.060]it is the most important criteria
[00:07:13.620]in terms of our probabilities for below normal temperatures
[00:07:16.580]during the winter period.
[00:07:18.220]And so we're gonna go through a few examples of that
[00:07:20.450]because this is a fairly strong event.
[00:07:23.030]It hasn't officially met strong criteria.
[00:07:26.860]Is it currently at moderate criteria,
[00:07:29.020]but based on what has happened over the last 30 days
[00:07:31.710]my suspicion is that we will,
[00:07:33.123]when it's all said and done with this
[00:07:34.380]we'll come into as a strong event.
[00:07:36.800]So there are certain snow patterns that occur
[00:07:38.940]during the week, moderate, and strong events
[00:07:41.280]and we'll go through those.
[00:07:42.700]Unfortunately, or fortunately, depending on your perspective
[00:07:45.440]as a transportation employee in snow removal,
[00:07:49.630]if you're looking at the Western part of the state,
[00:07:52.390]the odds are favorable, at least highly favorable
[00:07:55.060]that you'll see below normal snowfall this winter,
[00:07:57.040]not so much so in the Eastern part of the state.
[00:07:59.417]But the most important thing to give us a lead time
[00:08:02.280]in regards to changes within overall patterns
[00:08:06.300]is the area that Eastern Alaska and the Yukon territory.
[00:08:10.110]And what we look for to leave for that
[00:08:11.660]is about a seven to a 14-day lead
[00:08:14.590]in terms of the temperature anomalies there.
[00:08:16.760]Eventually they will reach us here in the lower 48.
[00:08:20.120]So I use the CPC forecasting tool
[00:08:23.790]look for the anomalies into the forecast future.
[00:08:26.850]In fact, one of those anomalies is starting to show up now
[00:08:29.230]in the six to 10 day and the eight to 14 day forecast
[00:08:33.784]for Eastern Alaska and the Yukon territory
[00:08:35.410]with a below normal temperature.
[00:08:36.810]So if that's starting to show up
[00:08:38.500]in their 10 to day forecast
[00:08:39.920]and you figure another seven to 10 days after that
[00:08:41.870]that would put that cold air infiltration into our region
[00:08:44.630]sometime right after the first full week of December.
[00:08:47.957]And in fact the (indistinct) have been hitting
[00:08:49.820]at that equation quite a bit here lately.
[00:08:53.120]So when we talk about La Nina
[00:08:55.290]really what we're doing is looking at
[00:08:56.810]the equatorial Pacific,
[00:08:57.930]and we're looking for an anomalous cope pool,
[00:09:00.370]and you can see from this graphic
[00:09:02.180]that there's a considerable amount
[00:09:03.700]of below normal sea surface temperatures all the way
[00:09:05.420]from the equatorial Pacific
[00:09:06.650]from essentially just to the East of Indonesia
[00:09:09.010]all the way over to South America.
[00:09:11.610]And in the Gulf of Alaska
[00:09:12.860]you'll notice that there's a fairly big warm pool.
[00:09:14.980]Now that warm pool, worst of the warmth,
[00:09:17.630]is now situated between the Hawaiian Islands
[00:09:20.920]and the Eastern Aleutian Islands.
[00:09:22.850]Two months ago that warm anonymous pool
[00:09:24.810]was all the way up into the central
[00:09:27.060]and Eastern Gulf of Alaska.
[00:09:29.070]So it's been displaced back toward the Southwest,
[00:09:31.450]and that's not common during the fall winter period
[00:09:35.390]as a low pressure system
[00:09:36.670]in the Eastern Aleutian Islands churns
[00:09:38.860]and that warm water is there to feed it.
[00:09:40.630]We see strong storm systems
[00:09:42.240]and that will eventually move toward the East
[00:09:44.650]and then it'll get retro gated back toward the West.
[00:09:47.670]And that usually occurs
[00:09:48.503]on about a six to eight week interval.
[00:09:51.390]So that is what we call our timing sequence
[00:09:53.710]in terms of patterns.
[00:09:55.170]So the architecture that we've seen in September
[00:09:57.260]and with a storm in October, basic,
[00:10:00.020]it was supported by a troughing pattern
[00:10:02.100]across the Eastern United States
[00:10:04.170]and a raging pattern across the Western United States.
[00:10:07.150]Since that time we have broken that down
[00:10:09.220]and we're getting more troughing action
[00:10:10.600]into the Western United States
[00:10:12.287]and more originally the Eastern United States.
[00:10:14.760]So the logical conclusion,
[00:10:15.960]isn't a six to week eight timeframe
[00:10:17.670]that will put us sometime in the first 15 days of December
[00:10:22.460]where we would start to see a phase change
[00:10:24.690]over toward enhanced troughiness
[00:10:26.690]in the Eastern United States.
[00:10:28.110]That does not mean that we will get Arctic air in here.
[00:10:30.060]It just means that more Arctic air
[00:10:31.530]was likely to flow eastward of the Rocky Mountains
[00:10:34.150]than westward of the Rocky mountains.
[00:10:35.700]And that sets us up a course.
[00:10:37.140]We're in the intersection
[00:10:37.973]between the West and the East
[00:10:39.380]for the potential to also share in that Arctic weather.
[00:10:43.070]If You look at the North Atlantic
[00:10:44.570]you'll notice that most of that is warm
[00:10:46.030]and there is one cold spot that is sitting there
[00:10:48.150]between England, excuse me, and Nova Scotia.
[00:10:52.960]This is the area that we watch
[00:10:54.470]for that high pressure development.
[00:10:56.550]And generally when that starts to occur
[00:10:58.210]you will see below normal sea surface temperature anomalies
[00:11:01.690]developing all across the North Atlantic
[00:11:03.930]from Greenland all the way over to Scandinavia.
[00:11:06.190]And then we'll start to see that current draw down
[00:11:08.900]the Western side of Europe
[00:11:11.140]and into the equatorial Atlantic region,
[00:11:14.417]the Eastern equatorial Atlantic region.
[00:11:16.100]So there are some signs of seeing some spottiness there
[00:11:19.260]but there's nothing concrete.
[00:11:21.150]There is more of a trend in the Gulf of Alaska recently
[00:11:23.890]then there isn't a North Atlantic.
[00:11:25.690]So until we start to see a more expansive area below
[00:11:28.383]and almost sea servers temperatures
[00:11:30.280]we're not likely to get a very strong North Atlantic block
[00:11:33.150]at least at this point in time.
[00:11:35.430]So when we talk about La Nina
[00:11:37.630]most of the La Nina events
[00:11:38.990]start to develop near the late summer.
[00:11:41.170]They maximize thereself right around Christmas time
[00:11:43.960]and then they start to dissipate as we go into the spring.
[00:11:46.700]The stronger the event, generally the longer lasting it is.
[00:11:49.207]The longer-lasting it means it goes farther
[00:11:51.610]into the spring period.
[00:11:53.420]Weaker events tend to die out
[00:11:55.010]generally before we even get through the full winter period.
[00:11:58.460]So when we look at the strength of this La Nina event
[00:12:01.800]and look at CPC's results or analysis of the event
[00:12:05.390]which was just updated here last Thursday
[00:12:08.090]they've now placed a 95% confidence interval
[00:12:10.790]that this La Nina event will carry through the entire winter
[00:12:14.030]and a 65% probability it'll carry through the entire spring.
[00:12:18.170]And the reason that is significant for us
[00:12:20.300]is that generally we start to see
[00:12:22.320]a pretty severe weather pattern develop during La Nina years
[00:12:25.360]down in Oklahoma in Texas during the early spring.
[00:12:28.910]And the quicker that event dies
[00:12:30.480]the earlier we start to see that severe weather.
[00:12:33.040]Now, the reason I bring that severe weather up
[00:12:34.820]is it takes a pretty intense low pressure system
[00:12:36.720]to develop severe weather down in the Southern Plains.
[00:12:40.440]And unfortunately, since we're North of that,
[00:12:42.240]we would be basically on the Northwestern side
[00:12:44.910]of the troughing pattern that would develop
[00:12:46.520]over the Southern Plains.
[00:12:48.070]So as that air is lifted northward
[00:12:51.030]you gotta deal with the Arctic air
[00:12:52.013]that is situated over Southern Canada
[00:12:54.470]in the Northern Plains.
[00:12:56.310]And if that cold air makes it in
[00:12:58.020]at the surface like last week,
[00:13:00.240]before the warm air Arawak gets into this region,
[00:13:02.780]you end up dealing with ice storms.
[00:13:04.590]And so one of the things
[00:13:05.423]that will come out of a La Nina event in the spring
[00:13:07.410]is that there's a tendency for more significant
[00:13:10.070]ice accumulations in the central United States.
[00:13:13.440]During the prime of the winter period
[00:13:15.000]we see that that most of that Arctic air
[00:13:17.430]that does infiltrate the Northern Plains
[00:13:19.010]pushes foreigners southward that the main line
[00:13:21.930]of icing generally occurs in Eastern Texas, Oklahoma,
[00:13:25.760]Arkansas, Southern, Missouri,
[00:13:27.560]and parts of very extreme Eastern Kansas.
[00:13:28.393]On occasion we'll get that up
[00:13:31.360]into the extreme Southeastern Nebraska.
[00:13:35.250]But for the most part our biggest ice risk
[00:13:37.840]for heavy ice accumulations are going into the winter
[00:13:41.320]and exiting out of the winter.
[00:13:42.630]During the middle of the winter,
[00:13:44.260]if we do get icing events,
[00:13:45.690]they generally tend to be those very, very
[00:13:47.480]light icing events, generally less than a 10th of an inch
[00:13:51.500]where your heavier rainfall events tend to occur
[00:13:53.480]in the spring.
[00:13:54.930]You will also notice to the South
[00:13:56.600]it was October through April
[00:13:57.960]tends to be a very, very dry pattern
[00:14:00.530]across the Southern United States.
[00:14:02.610]This is consistent with La Nina patterns.
[00:14:04.530]You have a weak Southern jet and a stronger Northern jet.
[00:14:07.210]So just think is a normal jet stream pattern supercharged
[00:14:11.500]that brings in more extreme cold when it does indeed occur.
[00:14:15.610]So these are specific areas in the equatorial Pacific
[00:14:18.780]and no need to really know anything.
[00:14:20.190]What I'm trying to show here is that this is the anomalies.
[00:14:24.130]So the El Nino 4 region is dead center
[00:14:26.720]in the equatorial Pacific.
[00:14:28.210]The 3.4 is about three quarters away
[00:14:33.240]to the halfway point of the equatorial Pacific.
[00:14:36.240]The El Nino 3 is halfway or a quarter way
[00:14:38.600]across the entire Pacific.
[00:14:40.610]And the El Nino 1+2 or the 1 and 2 region,
[00:14:43.800]is right off of the coast of South America.
[00:14:47.080]Generally, that is where we start to see the warm pockets
[00:14:49.540]start to materialize.
[00:14:50.680]It'll get drawn westward and start to weaken
[00:14:53.410]these other areas.
[00:14:54.680]So when you look at that you can see that all three regions,
[00:14:58.600]1, 2, 3 and 3.4
[00:15:01.178]out of the four regions shown here
[00:15:03.640]are all starting to show a weakness in their pattern.
[00:15:07.120]However, it really boils down to what's below the surface
[00:15:10.650]that will determine whether or not this weak-kneed trend
[00:15:12.730]will continue as we go forward in time.
[00:15:16.150]And here basically what we're doing
[00:15:18.250]is looking right down dead center the equatorial Pacific.
[00:15:21.560]So on your left side is Indonesia,
[00:15:23.550]on your right side is South America,
[00:15:25.540]and they're just looking straight down to the surface.
[00:15:27.880]So you'll notice that the currents
[00:15:29.210]bailing up over on the West side
[00:15:30.810]or the left side of your screen
[00:15:32.660]or essentially the currents that are under Indonesia
[00:15:35.120]and often along Australia,
[00:15:36.800]you see that warm pocket building
[00:15:38.320]and you can see that it's slowly drifting
[00:15:40.190]toward the central equatorial Pacific.
[00:15:43.090]Generally it takes six months for this process
[00:15:45.290]to move from all the way
[00:15:46.140]from that Western equatorial Pacific
[00:15:48.130]to the Eastern equatorial Pacific
[00:15:49.640]and get lifted up to the surface.
[00:15:51.630]However, you'll also notice in front of this pool
[00:15:54.740]that has basically stopped at the central editorial Pacific,
[00:15:57.650]there is a very large anonymous cold pocket
[00:15:59.810]below the surface that is making its way
[00:16:01.810]toward the surface in the Eastern equatorial Pacific.
[00:16:05.550]This is most likely the last significant pulse of cold water
[00:16:09.360]to reinforce this event,
[00:16:11.210]and these temperatures are basically in the area
[00:16:13.360]of four to five degrees celsius below normal.
[00:16:16.350]So if this comes to the surface and spreads out
[00:16:18.290]this would be that reinforcing shot
[00:16:20.140]that bring this event into the strong category.
[00:16:23.690]And generally in the strong category
[00:16:25.150]we start to see a pretty significant Arctic response
[00:16:27.730]across Southern Canada and the Northern Plains,
[00:16:30.650]and our probability is increased dramatically.
[00:16:33.450]We are far enough South where that our probabilities
[00:16:35.850]are not high enough for us to meet the criteria
[00:16:38.290]that you've seen in the previous screen.
[00:16:39.580]Those require 70% or greater probability.
[00:16:42.890]But when you go to the decoder
[00:16:44.260]the probabilities are between 70 and 80%
[00:16:46.690]of the OSI below normal temperatures during the winter time
[00:16:49.570]during La Nina.
[00:16:50.730]We're just barely below that.
[00:16:51.640]We're in the 60 to 65% likelihood that we will see
[00:16:54.930]below normal temperatures average for the winter.
[00:16:57.810]So when we look at all the numerical models
[00:17:00.100]across the globe,
[00:17:00.933]they all try to do a fixation on what was gonna occur
[00:17:03.540]with this event us as we go forward in time.
[00:17:05.720]And why as I draw your attention to this as you can see,
[00:17:08.180]one, there is a large spread in way these models
[00:17:11.350]are performing going forward.
[00:17:13.640]And then so if we take the averages of them,
[00:17:15.540]every one of them are consistent with being
[00:17:17.760]in a moderate event which is -1 degree celsius
[00:17:21.880]to a moderately strong, the strong event
[00:17:23.930]which is -1.5 to two degrees celsius
[00:17:26.220]or greater below normal,
[00:17:27.760]with at least a half a dozen of these models
[00:17:29.570]indicating that this event will get strong
[00:17:32.060]and of these half dozen of models,
[00:17:34.120]four of them predicted this event long before
[00:17:36.910]all the other models predicted this event.
[00:17:39.990]And in fact most of the models predicted
[00:17:41.890]that we'd be an El Nino this winter
[00:17:44.197]more toward an El Nino than we would be a La Nina event.
[00:17:48.000]So really what I was talking last winter on my talks
[00:17:50.510]was this appears to be a building pocket
[00:17:54.420]beneath the editorial Pacific.
[00:17:56.440]This cold pocket
[00:17:57.320]that was in the Western equatorial Pacific last winter
[00:17:59.940]was making its way eastward and it wasn't being unimpeded
[00:18:03.060]and to me that was a signal that we were gonna go
[00:18:04.910]into La Nina pattern as that's in deed what we've done.
[00:18:07.920]So if you were to exclude these models
[00:18:10.080]that are drastically warming this region
[00:18:14.260]from where the last official measurement
[00:18:17.370]which was September and you look forward in time,
[00:18:20.930]half of these models essentially say
[00:18:24.130]this event is gonna start weakening right now
[00:18:26.580]and we've already reached its peak.
[00:18:28.350]We get the subsurface heat content tell us that's not true.
[00:18:32.030]So if we exclude those models
[00:18:34.890]then really what the remaining models are saying
[00:18:37.320]is this advantage is likely to get very strong
[00:18:39.890]and it's likely to last.
[00:18:40.920]If you take it to go farther out in the future
[00:18:42.840]it's likely to last much longer
[00:18:45.100]than was originally predicted.
[00:18:47.100]And that's why CPC has increased their probability
[00:18:50.350]of us holding to the spring to 65%.
[00:18:52.360]It was below 50% last month.
[00:18:54.240]So that's a pretty significant mode of change,
[00:18:57.690]15% probability in one month.
[00:19:00.490]And if this continues,
[00:19:01.890]the biggest concern we have
[00:19:03.070]is this goes into a multi-year event.
[00:19:05.180]If this thing does not, by the first half of the summer
[00:19:07.590]reduce itself down to in that range
[00:19:10.240]of a half a degree celsius below normal
[00:19:12.080]to a half a degree celsius above normal,
[00:19:13.630]which is considered the normal range,
[00:19:15.810]then most likely we're facing a multi-year event,
[00:19:18.590]and generally year two the situation begins to intensify
[00:19:22.580]on the pattern that was established in year one.
[00:19:24.560]So we had a lot of drought problems
[00:19:25.940]in the Western part of the state.
[00:19:28.540]So our hope is that we will see
[00:19:30.080]the accumulated precipitation move into the spring period,
[00:19:33.090]because if this La Nina event could be restrengthened
[00:19:35.500]back into the late summer and fall,
[00:19:37.560]then we're gonna go through the same process.
[00:19:39.730]And the most likely scenario is that
[00:19:41.620]our high temperatures are gonna be much warmer
[00:19:44.350]than they were this past summer.
[00:19:46.150]We built on a lack of subsoil moisture.
[00:19:49.140]So that is the immediate concern for me going forward.
[00:19:52.620]Right now I would say that those odds are about 50/50
[00:19:55.590]that this event will occur,
[00:19:56.987]but in the same token.
[00:19:59.370]It does not mean that we won't get precipitation,
[00:20:01.680]because when I did this talk in the fall of 2012,
[00:20:06.960]of course, the concern was it carry over into 2013
[00:20:09.660]of the significant dry conditions,
[00:20:11.630]and we started looking at the precipitation
[00:20:14.060]that followed a very dry year in Western Nebraska
[00:20:17.467]and 70% of the time we see an above normal moisture
[00:20:20.970]for the yearly basis.
[00:20:22.190]However, it isn't well distributed across the year.
[00:20:26.210]We tend to see a concentration
[00:20:27.860]during the may and June period of heavy precipitation.
[00:20:30.980]So if that occurs, it can, to some extent,
[00:20:33.330]offset some of the situation that we had for the drought
[00:20:36.550]but we're gonna have to have continuous precipitation
[00:20:38.860]throughout the summertime
[00:20:40.280]or otherwise it'll rear its ugly head.
[00:20:42.810]So there's your very far outlook,
[00:20:44.460]but let's concentrate on what the trends tell us
[00:20:47.040]with La Nina.
[00:20:48.620]What NOAA has done is they've ranked La Nina events
[00:20:51.950]from strongest to weakest.
[00:20:53.330]So your strongest event on record was essentially
[00:20:56.670]in terms of that anomaly in that equatorial Pacific
[00:20:59.620]and that is defined by the temperature deviation from normal
[00:21:03.010]was in 1973, 74 winter.
[00:21:05.970]But as you go across your screen
[00:21:07.530]you would have two full rows, eight years,
[00:21:09.910]plus the next three on the left or right
[00:21:12.700]that were strong events.
[00:21:14.540]Out of these events for Nebraska,
[00:21:18.100]only three of the events were above normal
[00:21:20.780]in terms of temperatures.
[00:21:22.090]Eight of them were below normal.
[00:21:24.250]When you get into the moderate events is a 50/50 split,
[00:21:28.070]you're either cold or you're warm.
[00:21:29.970]So even with this strong of a correlation
[00:21:33.280]it still gets to be a little bit of a guessing game
[00:21:35.730]and that boils down to where the jet stream position itself
[00:21:38.510]is located.
[00:21:40.010]And it also really boils down to do we have a good snow pack
[00:21:44.780]to the North.
[00:21:45.770]If you go to the 1999 to 2000 winter
[00:21:50.110]and the 1998 to 1999 winter
[00:21:52.700]there was an absence of decent snow pack in Southern Canada.
[00:21:56.270]So we didn't have the Arctic air be...
[00:21:59.860]The Arctic air essentially was being warmed
[00:22:01.590]as it slowed southward over bare surfaces
[00:22:04.360]with the lack of snowfall
[00:22:05.372]and the air mass itself was moderated.
[00:22:07.840]Secondly, the intensity with a blocking a ridge
[00:22:12.290]in the North Atlantic just wasn't there.
[00:22:14.610]So you had more of a zone only flow.
[00:22:16.870]The trough in the East was kind of muted
[00:22:19.670]and directly most of that cold over the great lakes
[00:22:22.060]in the Northeastern United States
[00:22:23.490]and not bringing and filtering it down into the Heartland
[00:22:26.400]or here in the center part of the country.
[00:22:29.000]So I know we talked about these nice warm conditions.
[00:22:32.740]I would harken you back to what has occurred,
[00:22:35.160]and this is, unfortunately I can't do a 45-day,
[00:22:37.656]excuse me, a 75-day capita trans,
[00:22:40.300]so you're gonna see a 90-day and a 60-day.
[00:22:43.600]So it takes from the middle of August
[00:22:45.070]and the middle of September.
[00:22:46.500]Remember at the beginning of September,
[00:22:47.910]we opened up exceptionally cold
[00:22:49.560]but we ended August exceptionally warm.
[00:22:52.090]But these individual events kinda get forgotten about
[00:22:55.980]in the overall trend of things,
[00:22:57.810]and what we've noticed for this fall,
[00:23:00.100]if you look at the 90-day temperature trend
[00:23:02.420]and you look at the 60-day temperature trend
[00:23:05.300]below normal temperatures are infiltrating the central part
[00:23:08.630]of the United States.
[00:23:09.760]And if that pattern continues
[00:23:12.670]that we're basically already below normal
[00:23:15.050]for our winter temperatures.
[00:23:16.720]So don't get caught up on these warm trends.
[00:23:19.410]What scares me more about warm trends
[00:23:21.440]at this time of the year
[00:23:22.660]is when I start hearing record high temperatures
[00:23:25.320]followed by record low temperatures.
[00:23:27.740]That is not uncommon during this type of a pattern
[00:23:30.320]because in order to get those record high temperature
[00:23:32.871]you have to have a big strong ridge
[00:23:34.220]to bring that warm air to the North
[00:23:36.390]and the atmosphere balances itself.
[00:23:38.130]So if you have a big ridge on the West side
[00:23:39.900]and the East side, you're gonna have big troughs.
[00:23:41.810]So the changes tend to be dramatic.
[00:23:44.280]You tend to see a lot of higher wind events
[00:23:46.090]under this type of pressure pattern changes.
[00:23:49.120]Whereas when you look at Alberta Clippers
[00:23:52.630]that are basically coming in
[00:23:54.690]through the backside of a trough
[00:23:56.820]and we get continuous amounts of those types of systems
[00:23:59.300]you get a quick pressure change,
[00:24:01.500]about a three-hour wind event,
[00:24:03.460]the Arctic air surges in,
[00:24:04.710]things relax until the next wave comes through.
[00:24:07.580]But when big long wave troughs move in
[00:24:09.160]from the Western United States,
[00:24:10.100]you're gonna get two, three days of high wind events
[00:24:12.920]before that whole system itself moves through.
[00:24:15.650]And when you get on the backside of it
[00:24:16.910]you deal with the winds out of the polar opposite direction
[00:24:19.890]of the same magnitude.
[00:24:21.840]So the precipitation probabilities
[00:24:24.620]for our part of the country are a little bit trickier.
[00:24:27.370]First of all, we only get seven to 9%,
[00:24:30.860]depending on location of the state
[00:24:32.210]of our annual precipitation in the winter time.
[00:24:35.413]What that boils down to in Western Nebraska
[00:24:37.990]liquid equivalency less than an inch and a half
[00:24:40.400]in the Northwest,
[00:24:41.820]you get down into extreme Southeastern Nebraska,
[00:24:44.010]you're looking at close to three inches of liquid water.
[00:24:46.890]So what we look for is to look at
[00:24:49.190]these real anomalous patterns
[00:24:50.640]because it kind of gives us a storm track.
[00:24:52.450]And what you will notice is that quite frequently
[00:24:55.050]you'll see a Southwest to Northeast
[00:24:57.980]running anomaly of above normal precipitation.
[00:25:01.650]And in a lot of these cases
[00:25:02.900]and you look at these strong events,
[00:25:04.470]they're centered around Eastern Texas.
[00:25:07.060]And if they're farther northward, of course,
[00:25:09.100]some of those can touch up into Southeastern portions
[00:25:11.910]of Nebraska, but for the most part
[00:25:14.060]it takes that heavy precipitation to our East
[00:25:16.360]and our Southeast up through the Ohio River Valley.
[00:25:19.760]Now this is not every single time,
[00:25:22.550]but when you look at all of the strong events
[00:25:24.950]this is the predominant trend that form the central
[00:25:29.130]and Eastern Corn Belt.
[00:25:30.010]We except exceptionally wet conditions.
[00:25:32.730]We expect much drier conditions across the Southern Rockies
[00:25:36.360]and those Southwestern and Southern panhandle of Nebraska.
[00:25:40.730]So let's look at the precipitation trends
[00:25:42.930]because we've already seen what the fall has given us
[00:25:45.950]in terms of temperatures.
[00:25:48.630]And in terms of precipitation, really,
[00:25:50.970]the pattern that established itself this summer
[00:25:53.820]across the Western part of the state,
[00:25:55.400]really has not broke down much.
[00:25:57.260]So we're still seeing a dry trend
[00:25:58.980]if we load in the middle of September and last night
[00:26:01.590]your 60 days and the last 90 days from August,
[00:26:04.040]a similar trend.
[00:26:05.490]What you do see though is some above normal moisture
[00:26:09.010]starting to show up in these anomalies
[00:26:10.840]in North central Texas eastward.
[00:26:13.970]So you can kinda see that a robust precipitation pattern
[00:26:16.780]is moving from Texas all the way
[00:26:18.850]up into the Southern Ohio River Valley.
[00:26:21.200]That is your base of your trough
[00:26:24.340]or the front side of your trough,
[00:26:26.070]the main position that is set up,
[00:26:27.960]over basically the Eastern United States.
[00:26:31.060]And if, like I said, most of these periods
[00:26:33.190]was dominated by the Eastern U.S. trough
[00:26:35.160]and now we moved to a Western U.S. trough.
[00:26:36.930]So we would expect that if we were to look at this
[00:26:39.570]in another six weeks, that this anomalous trend here
[00:26:43.060]would disappear somewhat in the shorter term.
[00:26:45.660]It would be replaced by a below normal precipitation,
[00:26:49.660]and we would see the anomalous precipitation
[00:26:51.660]starting to show up more in the Pacific Northwest
[00:26:53.850]in the Northern Rockies.
[00:26:55.850]So when we talk about snowfall for LA Nina
[00:26:58.670]you really have to quantify it by the strength of the event.
[00:27:02.360]When you look at the average snowfall pattern
[00:27:04.020]for all LA Nina events
[00:27:05.250]you see that the core areas,
[00:27:06.560]significant departures where snowfall was up
[00:27:08.700]in the black Hills and also up
[00:27:11.020]in the upper Mississippi River Valley,
[00:27:12.790]Minnesota and the Red River Valley of Eastern North Dakota.
[00:27:16.990]But you also notice the Southern half of the panhandle
[00:27:20.900]southward through the South...
[00:27:22.900]Southward and southeastward through Southwest Nebraska,
[00:27:26.150]all the way to Western Kansas
[00:27:27.960]down to the Texas panhandle in the Southwest
[00:27:30.620]show below normal snowfall.
[00:27:33.460]And in most of these cases, that four inches of departure
[00:27:36.860]for snowfall and the season down in Texas
[00:27:38.770]equates to about a 25 to 30% reduction
[00:27:41.800]in their seasonal snowfall.
[00:27:43.460]For the Southwest and Southern panhandle
[00:27:45.760]that relates to about a 10% reduction in snowfall
[00:27:48.860]for all events.
[00:27:50.400]However, when you get to week events,
[00:27:53.630]you tend to have both the Northern
[00:27:55.860]and the Southern jet competing.
[00:27:57.640]And that brings a moisture anomaly channel
[00:27:59.960]or where the two jet streams kinda merge together
[00:28:03.410]right across the central United States.
[00:28:05.760]So we tend to see above normal moisture
[00:28:07.390]in the Eastern half of the state, pretty much normal,
[00:28:10.190]excuse me, above normal snowfall,
[00:28:12.400]normal snowfall for a much of Western Nebraska
[00:28:14.750]outside that core area,
[00:28:15.877]the Southern panhandle in the Southwest.
[00:28:19.650]So we see departures that are consistent
[00:28:21.560]with the previous slide, somewhere between 10
[00:28:24.717]and in some locations, 20% snowfall reduction.
[00:28:28.660]However, when you get to the stronger event
[00:28:31.580]notice that your snow pack anomalies gets shifted
[00:28:34.370]well up toward the North in Southern Canada,
[00:28:37.410]just the North of Montana all the way through
[00:28:40.230]the upper Mississippi River Valley,
[00:28:42.170]and we see a strong anomalous below normal snowfall trend
[00:28:46.080]not only for portions of the Southwest and the panhandle
[00:28:49.520]but significantly below normal
[00:28:51.590]for North Central and Northeastern Nebraska.
[00:28:54.610]So unfortunately NOAA didn't do the moderate events,
[00:28:57.063]there's only four of them.
[00:28:59.290]And so the statistics is can really get thrown for a loop,
[00:29:02.030]but the general trend is that for week events
[00:29:04.500]of snowfall anomaly lays basically across about 300 miles
[00:29:08.960]to the South, during strong events 300 to 600 miles
[00:29:13.080]to the North.
[00:29:14.480]So the intermediate range would be
[00:29:16.870]basically across the Dakotas and Eastern Montana.
[00:29:19.900]Why do I bring this up?
[00:29:21.110]I've mentioned we're watching snowfall.
[00:29:23.330]Look at where the anomalous snowfall pattern is right now.
[00:29:26.250]This is where we got our greatest snow depths.
[00:29:28.710]It's in that area of Eastern Porsche
[00:29:31.610]just to the North of Montana
[00:29:33.790]right across the Southern Canadian Prairie Province regions.
[00:29:37.230]And it's trying to fill in
[00:29:38.940]toward the Western Great Lake.
[00:29:40.390]So this is consistent with a strong La Nina event.
[00:29:44.240]And the reason that this is important as I said before,
[00:29:46.680]the deeper the snow pack,
[00:29:47.970]the more likely that that Arctic gear will not be modified
[00:29:50.880]as it's pulled toward the South,
[00:29:52.670]and we will see more of that in our region.
[00:29:55.150]So our major concern is if we're gonna see
[00:29:57.390]Arctic air intrusions,
[00:29:58.510]can we get enough precipitation events
[00:30:00.690]to get the surfaces weteded up enough to act as a buffer
[00:30:04.530]to keep the cols from penetrating deep into the ground.
[00:30:07.170]We used a lot of moisture up this growing season.
[00:30:09.260]There's very little of it in the profile.
[00:30:11.380]We know we're working from the top-down
[00:30:13.100]in most areas of the state,
[00:30:14.440]meaning that there's down to four or five feet.
[00:30:16.440]There's just nothing there.
[00:30:17.430]Were bone dry.
[00:30:18.570]It was used up during the growing season.
[00:30:20.850]So in Eastern Nebraska, of course, with the clayier soils
[00:30:23.340]you get a lot of cracking.
[00:30:24.930]If you don't wet that surface up and seal it up
[00:30:27.060]the top one to two feet of their profile
[00:30:28.810]get it up to fill capacity,
[00:30:30.690]those cracks remain open
[00:30:31.970]and that cold air is able to penetrate much deeper.
[00:30:35.390]This is when we have our problems
[00:30:37.120]with a lot of infrastructure,
[00:30:38.690]basically looking at sewer lines, gas lines,
[00:30:41.810]those things that are buried below frost level
[00:30:44.370]tend to be more vulnerable during La Nina events
[00:30:46.730]where we don't have good precipitation.
[00:30:49.250]So we can't get big precipitation events
[00:30:52.230]leading into the winter with La Nina events.
[00:30:56.010]If we were able to drop a good footage snow
[00:30:58.090]on to unfrozen surfaces, that would act as a good buffer
[00:31:01.810]just like the snowstorm did right before Thanksgiving.
[00:31:05.530]Excuse me right before Halloween, I apologize for that.
[00:31:10.370]So without that, that would be my major concern.
[00:31:14.770]Secondarily, without that significant moisture
[00:31:17.930]the sandier soil of Western Nebraska
[00:31:20.040]are gonna be exceptionally vulnerable to wind erosion.
[00:31:24.270]And these light precipitation events, although welcome,
[00:31:26.840]are insufficient to get those profiles wetted up.
[00:31:30.580]What we really need to see
[00:31:31.630]is what we've seen in Eastern Nebraska
[00:31:32.907]in all these last couple events.
[00:31:34.730]Three quarters of an inch to an inch and a half
[00:31:36.570]of moisture over a 24-hour period to get those profile.
[00:31:40.290]An inch of moisture in Western Nebraska
[00:31:42.110]is the equivalent of two,
[00:31:42.943]which is the oyster in Eastern Nebraska.
[00:31:44.790]You fill that profile up that top foot.
[00:31:47.340]You can hold one inch available in the sandier soils
[00:31:49.260]of Western Nebraska can hold two inches in Eastern Nebraska.
[00:31:52.530]So it's gonna take four inches of moisture minimum
[00:31:56.580]for us to get this soil profiles to the point
[00:31:59.160]in Eastern Nebraska, that I feel comfortable
[00:32:01.000]that we're not gonna get deep Arctic penetration.
[00:32:03.350]Why is this important also?
[00:32:05.070]We don't want that ground to freeze up
[00:32:06.560]in case we get late winter snows
[00:32:08.600]and we don't want that ground to freeze up
[00:32:10.420]and the streams to freeze up then throw the snow
[00:32:12.610]on top of it.
[00:32:13.850]Then we put ourselves into a situation
[00:32:15.670]just like we faced here a couple years ago
[00:32:17.900]with a risk for flooding,
[00:32:19.370]spring flooding increases dramatically.
[00:32:21.660]It's not as much the ice on the rivers.
[00:32:23.770]It's just the combination of the ice
[00:32:25.280]followed by heavy deep snowfall,
[00:32:27.350]particularly there in the month of February.
[00:32:29.370]That has been our killer in the past
[00:32:31.220]and probably will be a killer in the future
[00:32:33.150]in terms of flood risk.
[00:32:34.850]So we look at CPCs rolling three month outlook.
[00:32:38.590]And the reason bring this up is tomorrow morning
[00:32:40.570]there's gonna be an update of this
[00:32:42.780]as they look out toward their newest update.
[00:32:45.360]So this was issued last month.
[00:32:50.310]And one of the things that we've been watching,
[00:32:52.640]particularly up on the upper hand left,
[00:32:54.720]has been the introduction of below normal temperatures
[00:32:57.920]in the December through February time period.
[00:33:01.280]If you pay attention to these as I have to,
[00:33:03.750]because I'm getting paid to do that
[00:33:05.720]what we have noticed is is that over the last four months
[00:33:08.610]the trend has went from July for this area during December
[00:33:13.260]to be showing normal, the above normal temperatures
[00:33:15.980]across the entire lower 48 to a slight introduction
[00:33:19.860]to below normal temperatures during the month of September
[00:33:22.860]across Montana,
[00:33:24.400]to a further southward reduction during October.
[00:33:27.700]And my suspicion is based on the intensity forecast
[00:33:30.430]that was issued by CPC last Thursday.
[00:33:33.080]I would be shocked that we don't see
[00:33:34.420]a little bit further southward in Eastern displacement
[00:33:37.270]of the anomaly that is shown here
[00:33:39.650]on the upper left-hand side for the December
[00:33:41.530]through February period.
[00:33:43.200]Furthermore, if this event is gonna stay longer
[00:33:47.223]then it is very possible that in that March, April, May,
[00:33:50.880]which is your second line, left-hand side,
[00:33:55.480]we may see that being pull farther southward also.
[00:33:59.020]And that's not uncommon to see very nasty conditions
[00:34:02.680]at the end of the winter, with La Nina's big snows
[00:34:05.990]as with that event weekends get a dry colder pattern.
[00:34:10.060]During the month of March, we start to warm up
[00:34:13.297]and then we start to get the moisture coming in
[00:34:15.586]during the late April and in the May period.
[00:34:19.640]And generally because of the increased cloud cover
[00:34:22.940]we tend to go below normal in terms of temperatures,
[00:34:25.280]just like we did last spring.
[00:34:28.970]Here's the one that is really uncertain
[00:34:30.940]in terms of what we're gonna go forward-wise.
[00:34:33.900]There is a considerable amount of emphasis
[00:34:36.810]on above normal moisture,
[00:34:37.900]all the way from the Northern Rockies
[00:34:39.210]to the Northern Great Lakes this winter time.
[00:34:42.120]If this verifies I'm gonna be a hero on this
[00:34:45.270]because that would lead to an increased snow pack
[00:34:48.130]to our North above normal.
[00:34:50.240]And that means that that snow pack is even farther southward
[00:34:53.970]than it currently is.
[00:34:55.480]Which means there's even less time for that air to modify
[00:34:57.920]before it reaches Nebraska.
[00:34:59.780]So the only thing that will keep it
[00:35:01.160]from coming into our region is whether or not we get
[00:35:04.660]that blocking ridge over the North Atlantic.
[00:35:07.150]And if it doesn't develop,
[00:35:08.800]then this cold air will stay shunted toward the East
[00:35:10.860]and we're gonna have a very benign winter
[00:35:12.260]and I'll look like a fool, but you won't remember it
[00:35:14.600]because you'll be happy with the real nice conditions
[00:35:16.720]we have this winter.
[00:35:18.270]But you'll remember this, if this does occur
[00:35:20.650]and this cold air comes in and say, "How did he do that?"
[00:35:23.620]This is basically just using the climatological
[00:35:25.980]statistics that are available to me to be able to project.
[00:35:29.430]What is more concerning and as you can see,
[00:35:32.920]when I talk about those dry trends in the late winter
[00:35:35.960]and into the early spring period,
[00:35:37.900]particularly that March, April, May,
[00:35:39.570]you can kinda see how on the first row,
[00:35:43.770]the very far right, which is February through April,
[00:35:46.850]and then the next row on the back on the left-hand side
[00:35:50.520]which is the March through May,
[00:35:52.210]you can see that that dry tongue
[00:35:53.900]that comes into the Central Plains.
[00:35:56.050]So this is also a consistent LA Nina forecast.
[00:36:00.160]The biggest issue, of course, is when we go forward in time.
[00:36:03.080]And you'll notice this when we get in the April through June
[00:36:06.020]and then beyond, there's not a lot of signal
[00:36:08.550]outside of a wet trend during the end of the summer period
[00:36:11.680]for our part of the region.
[00:36:13.013]That doesn't surprise me whatsoever
[00:36:14.930]because there's not a lot of uncertainty
[00:36:16.370]with La Nina events, whether they're gonna carry on or not.
[00:36:19.310]And so we can tell we get a good picture
[00:36:21.120]and that won't be till probably late February, March,
[00:36:23.940]whether or not this event's gonna go into the summer,
[00:36:26.630]is probably not gonna have much of an impact
[00:36:28.460]on these precipitation probabilities that you see here.
[00:36:32.210]They're probably gonna remain fairly consistent.
[00:36:34.980]It's really, once we get into late winter,
[00:36:36.680]when we will most likely see a big change
[00:36:40.090]in where they are shooting the above normal moisture.
[00:36:43.090]But in past La Nina events,
[00:36:44.930]the wet transit established in the wet late winter,
[00:36:47.400]particularly in the Eastern Corn Belt,
[00:36:49.120]usually do follow through
[00:36:50.280]during the first half of the spring.
[00:36:52.030]And that's one of their biggest issues,
[00:36:53.740]is being able to plant.
[00:36:55.160]For us here in Western Nebraska,
[00:36:56.980]particularly the transportation end of it,
[00:36:58.660]and I mentioned it earlier,
[00:37:00.310]the biggest risk is that we start to see a certain pattern
[00:37:03.060]that we've seen here the last couple of weeks
[00:37:04.950]where troughs coming to the Pacific Northwest
[00:37:06.820]it kinda split the energy a little bit,
[00:37:08.370]so it moves toward the East, across the Northern Plains.
[00:37:11.020]Some of it dies to the Southeast toward The Great Basin
[00:37:14.670]and then eventually start to pull out into Texas.
[00:37:17.810]If that does start to materialize in full onas
[00:37:20.320]during the second half of the winter
[00:37:21.620]then I would expect some late season snows
[00:37:23.630]to increase across the Northwestern half of the state,
[00:37:28.160]and the highest probability would be the Northern half
[00:37:30.210]of the panhandle associated with that bullseye you've seen
[00:37:33.280]across the Black Hills on the snowfall anomalies
[00:37:35.840]for LA Nina events.
[00:37:37.630]That is not unusual for us
[00:37:40.380]to get these late season snows.
[00:37:42.080]We seen it last year,
[00:37:43.830]and I wouldn't be surprised we see it this year.
[00:37:46.070]The question is how much snowfall do we get until then?
[00:37:48.597]And right now the statistical odds say
[00:37:51.130]that most of the events that occur
[00:37:53.070]are either gonna be Alberta Clippers
[00:37:54.980]or like we've seen during the, excuse me,
[00:37:59.630]we've seen during the October event
[00:38:01.410]and to to an extent, similar extent, the September event.
[00:38:06.150]Cold air come right now the front range
[00:38:08.330]of the Rocky mountains in Montana,
[00:38:10.080]slid all the way down to Texas, creates an up slope flow.
[00:38:14.250]So the higher elevations of the Northern panhandle
[00:38:16.910]got a much better up slope flow
[00:38:18.620]to generate orthographic lift.
[00:38:20.620]You have a little bit lower elevations as you go southward.
[00:38:23.940]So you kinda get caught between the Pacific moisture
[00:38:26.300]to the North, and it's not far enough South
[00:38:29.720]where we can draw fast enough Gulf moisture up
[00:38:32.330]to spin around that low pressure system
[00:38:34.130]as it heads South along the front range.
[00:38:36.610]So you get the lighter prentensity of snowfall
[00:38:38.750]across Western Nebraska.
[00:38:40.410]Only as it digs down into Colorado
[00:38:42.640]do you see the snowfall intensity increase
[00:38:44.900]as it gets closer to the gulf.
[00:38:46.540]So we kinda get split
[00:38:47.580]between these two areas of precipitation.
[00:38:50.290]Until these troughs come out in one single unit,
[00:38:53.290]coming in to the Western United States
[00:38:55.820]not moving South East through to the Great Basin,
[00:38:57.900]but southward along the Gulf,
[00:38:59.877]excuse me, along the Western coast,
[00:39:02.400]and then starting to move in through the desert Southwest.
[00:39:05.540]Those are the big systems.
[00:39:07.120]When we see those, Katie bar the door.
[00:39:09.880]Usually the Western half of North Dakota
[00:39:14.210]and South Dakota get hit
[00:39:15.100]with some pretty good sized snow storms.
[00:39:17.610]But until that happens, until we see signs of that happening
[00:39:21.460]the La Nina statistics would have be favored
[00:39:24.020]in there right now.
[00:39:25.090]It doesn't look pretty
[00:39:26.280]in terms of overall seasonal snowfall.
[00:39:29.510]So I wanna show you some pressure, the gesturing pattern.
[00:39:32.930]This is just a short term look going out in the future,
[00:39:36.740]but it does hit it a couple of the emphasis
[00:39:38.850]that I was talking about.
[00:39:40.230]One, if you look on the right hand side of your screen,
[00:39:43.810]you'll notice that it's basically kind of like
[00:39:45.920]a straight line going up.
[00:39:47.540]There's really nothing there ridge-wise.
[00:39:50.640]But now if you start to see that that trough is digging
[00:39:53.470]and you notice that the line's starting
[00:39:55.350]to head on a straight northward fashion,
[00:39:57.430]is trying to carve out some blocking pattern there
[00:39:59.927]and until we get a big block developing there,
[00:40:03.990]the Arctic air that comes down is gonna be more directed
[00:40:06.730]toward the Great Lakes in the Northeastern United States.
[00:40:09.660]Secondarily, you can see that the energy
[00:40:11.500]coming the Pacific Northwest really never dig down
[00:40:14.680]in the Western coast of the United States.
[00:40:17.140]It just kinda has inland and peters out
[00:40:19.230]and moves that energy across the Northern Plains.
[00:40:21.470]So if you look at the main recipient of this
[00:40:23.680]is the Northern Rockies
[00:40:25.180]and those areas immediately downstream
[00:40:26.860]are the Canadian Rockies
[00:40:28.060]and the Alberta Prairie Province region.
[00:40:29.950]Those reds represent energy or lift.
[00:40:32.460]So you can see that most of those staying
[00:40:34.080]deflected to the North of us were just getting clipped
[00:40:37.350]here in Nebraska.
[00:40:38.810]Oops, let's take this out.
[00:40:40.228]Sorry, I'm sorry.
[00:40:41.200]So we take this out and this goes into December.
[00:40:43.300]You can notice that a large trough is starting to build
[00:40:46.280]in the Gulf of Alaska and it looks like it's being projected
[00:40:49.440]to move on shore as we get toward the end of the month,
[00:40:52.580]and start to carve energy out.
[00:40:54.720]It is these types of troughic banners
[00:40:56.460]that we have to watch out for
[00:40:58.050]for the connection to pull it hard to get into our region
[00:41:00.930]and representing a phase.
[00:41:02.450]Now you see the Ridge building in
[00:41:03.670]behind this low pressure system.
[00:41:06.010]What I do know as a meteorologist
[00:41:07.810]is that a lot that this most likely will not verify
[00:41:10.260]because it's been showing a lot of changes from day to day.
[00:41:13.470]But it's been consistently hinting
[00:41:14.810]that something is going to occur
[00:41:16.240]rather large across the Western United States.
[00:41:18.270]It just can't lock in to the exact day.
[00:41:21.600]What we see in the past when we started to see
[00:41:23.430]this break off of upper and lows like this
[00:41:25.470]on the two big storm systems as we got closer to the event,
[00:41:29.010]all of a sudden we started to see it
[00:41:30.370]come as a single unit trough across.
[00:41:32.940]So be watching this area because
[00:41:35.670]if what I think is going to occur occurs,
[00:41:38.790]we'll eventually see that trough moving
[00:41:40.390]into the Western United States.
[00:41:41.720]It will tap the Arctic air that is currently in place
[00:41:44.100]across Eastern Alaska and the Yukon,
[00:41:46.260]it will draw that down at the same time
[00:41:48.410]you can start to see here that the trough
[00:41:50.670]is starting to deepen somewhat to the East of Greenland
[00:41:54.650]and that ridge is starting to build up.
[00:41:56.960]And if that gets strong enough,
[00:41:58.980]then this low pressure system will absorb that energy.
[00:42:02.270]It will rotate and pivot around piece of energy around it
[00:42:05.160]in a constant basis for the next four to six weeks.
[00:42:08.010]And on occasion, one of those will get far enough
[00:42:11.130]up into the Arctic circle with a relaxation
[00:42:14.790]of winds that it will pull back cold air straight South
[00:42:17.890]along the front range of the Rocky mountains
[00:42:19.400]and we'll go through an Arctic blast.
[00:42:21.460]So here's how I see things going on.
[00:42:23.920]I still believe that our winter temperatures
[00:42:25.500]are gonna be below normal.
[00:42:26.520]I'm not gonna back off on that one bit.
[00:42:28.560]I don't see anything right now
[00:42:30.170]that would argue against that,
[00:42:31.510]especially with the Arctic air that has already built up
[00:42:34.320]in record proportions and portions of Alaska in the Yukon.
[00:42:38.950]Do expect large fluctuations in temperatures.
[00:42:41.270]We've seen that consistently this fall.
[00:42:42.930]I see no reason for that to break down going forward.
[00:42:46.850]The only exception would be that in the past
[00:42:49.600]when we get a real significant Arctic air surge,
[00:42:52.290]we lock that upper air trough
[00:42:54.540]across the Eastern United States in for a few weeks.
[00:42:57.210]Those don't happen all the time.
[00:42:58.293]There's probably about a one out of every four winters
[00:43:01.988]where we can get a long extended period of 30 plus days
[00:43:05.220]of those types of conditions.
[00:43:06.260]But generally they will hold for seven to 10 days.
[00:43:08.930]They'll break down, reload, then they will get another blast
[00:43:11.990]of that cold air.
[00:43:13.450]There should be a very strong tendency
[00:43:15.440]based on previous statistics of La Nina events
[00:43:18.600]that we will see below normal snowfall this winter
[00:43:20.920]across the Southern panel of Southwest Nebraska.
[00:43:23.670]We're gonna be within that normal range
[00:43:25.450]across the remainder of the state at this point in time.
[00:43:28.520]Now take it with a grain of salt.
[00:43:30.930]Normal does not mean average.
[00:43:32.670]Normal is a distribution of the snowfall.
[00:43:35.570]So for Lincoln, normal is about 27, 28 inches
[00:43:39.790]but the normal distribution is between 22 and 35 inches.
[00:43:45.480]We don't see anything to say we're gonna be exception,
[00:43:47.740]lacking a snowfall or exceptionally strong
[00:43:49.860]in terms of snowfall at this point in time.
[00:43:52.900]First half of the winter,
[00:43:54.420]based on the fact that we're about three to four weeks
[00:43:57.590]into the phase change for the troughing pattern
[00:43:59.770]being favored for the Western United States,
[00:44:01.570]and knowing that around week six to eight
[00:44:03.890]we should see that translate to a trough
[00:44:05.590]in the Eastern United States,
[00:44:07.380]we should start to see Arctic air intrusion
[00:44:09.350]starting to come into our region in a more frequent basis
[00:44:12.000]as we get into the second half of December,
[00:44:15.010]and possibly even earlier than that
[00:44:16.670]depending on how the troughing pattern
[00:44:18.190]over the Pacific Northwest pulls that big storm
[00:44:20.620]into the Northern Rockies.
[00:44:22.240]The second half of the winter, we see the troughing pattern,
[00:44:24.760]at least I do, easing up in the Eastern United States
[00:44:27.900]returning to the Western U.S. trough
[00:44:29.880]like we've been seeing lately.
[00:44:31.510]That's when we have our best chances
[00:44:33.410]for those big snow storms.
[00:44:35.370]And generally based on past La Nina experiences
[00:44:37.900]they'll occur during the month of February
[00:44:41.460]into the first 10 days of March.
[00:44:43.740]for the Eastern half of the state.
[00:44:45.500]For the Western half of the state,
[00:44:47.550]you can include both of those months
[00:44:49.760]because we are at a higher elevation.
[00:44:52.230]The colder temperatures lasts a little bit longer
[00:44:54.137]the snowfall last a little bit longer in the month of April.
[00:44:57.830]Eastern Nebraska, those events start to become
[00:45:00.100]more of a heavier rain events than snow events.
[00:45:04.470]We're just about a lot of our big, heavy icing period.
[00:45:07.560]There's still a few weeks where we can still get
[00:45:09.820]those types of ice scene events.
[00:45:11.410]What we've seen last week, let's hope it's not a prelude
[00:45:13.810]to what is likely to occur
[00:45:15.810]somewhere within the central and the Southern Plains
[00:45:18.210]on a frequent basis.
[00:45:19.740]My bet is that most of that will be the area
[00:45:22.450]from North central Texas up through Kansas City area
[00:45:26.170]into the Southeast area, with the highest ice accumulations
[00:45:28.640]till we get into late February, March.
[00:45:32.600]And then of course,
[00:45:33.433]the jet stream starts slipping to the North
[00:45:34.770]and we start pulling that chance for those ice storms
[00:45:37.300]up a little bit farther toward the South.
[00:45:39.160]That's if the trough in the West is the big player,
[00:45:41.640]which I believe it will be.
[00:45:43.730]So the flood risk this spring right now
[00:45:46.980]it's not there on our streams.
[00:45:49.570]However, if we build up a substantial ice pack
[00:45:52.460]and then we follow with heavy snow fall,
[00:45:54.900]that changes the whole equation dramatically.
[00:45:57.110]But at this point in time
[00:45:58.670]that's probably the most favorable thing
[00:46:00.110]we got going in for us,
[00:46:02.080]is we don't have wet soils at the surface.
[00:46:06.790]We have a lot of ability to absorb precipitation events
[00:46:09.730]if we don't freeze the surface up.
[00:46:12.430]It therefore really boils down to how cold it will it be.
[00:46:15.840]The first half of the winter is that deep ice on our rivers
[00:46:18.230]and our streams,
[00:46:19.450]and whether or not we throw big snowfalls
[00:46:22.520]at the end of season with sudden warmups
[00:46:25.540]as we go into the early spring period.
[00:46:34.690]I believe that's most of my short thoughts.
[00:46:42.040]So if you've got any questions be glad to ask them
[00:46:44.112](indistinct)
[00:46:45.274]That was amazing Al.
[00:46:47.060]You're like Ken Shimek on steroids.
[00:46:49.240](Al laughing)
[00:46:50.260]Wow!
[00:46:51.560]There's a lot that goes into that,
[00:46:53.560]predicting the weather and, you know.
[00:46:55.270]Well, I've always said if I can't dazzle you
[00:46:56.900]with brilliance I'm really gonna baffle you good here.
[00:46:59.319](laughing)
[00:47:03.200]Well, for me, it's really good to hear
[00:47:05.970]about the springtime flooding risk.
[00:47:10.590]I'm glad that's low right now.
[00:47:13.460]I hope it stays that way.
[00:47:14.900]I would say one thing on the spring flooding risk
[00:47:17.320]and this relates to outside of our region,
[00:47:20.120]if you pay attention to what has been happening now
[00:47:22.270]these snow storms, we're getting incredible snow pack
[00:47:25.140]build up in the Northern Rockies right now.
[00:47:27.090]That would be your upper Missouri River basin.
[00:47:30.310]Of course, with the drought situation we had last winter,
[00:47:33.408]we have a lot of storage room at our surfaces
[00:47:36.180]all the way downstream.
[00:47:38.340]However, be aware that
[00:47:42.730]they're already watching this unfolding
[00:47:45.270]because we've had such a strong start to the snow season.
[00:47:48.510]So we've not yet seen in the past.
[00:47:50.040]It can be without precipitation here in Nebraska
[00:47:52.177]and we could still end up having significant flood issues
[00:47:55.510]on the main stem with the Missouri,
[00:47:57.430]and a lot of the deals with upstream.
[00:47:59.520]So if you get that big snow packs there,
[00:48:02.100]generally we get that area, you know,
[00:48:03.860]when we had the 2011 event we had a tremendous snow pack.
[00:48:07.710]We got a big precipitation event in April
[00:48:10.050]on top of that big rainfall event.
[00:48:13.150]If you look at those probabilities that I showed you
[00:48:15.750]that area is typically dry during April and June.
[00:48:19.240]Typically doesn't mean it will be,
[00:48:21.960]but if this event breaks down earlier
[00:48:24.400]that tilts the odds a little bit more
[00:48:26.620]that the rains will come a little bit earlier.
[00:48:29.330]Generally under those La Nina conditions
[00:48:32.420]the Dakotas are good recipients of above normal wash
[00:48:35.800]of the second half of the summer,
[00:48:37.050]because they're downstream
[00:48:38.450]from our incredible moisture source that is melting
[00:48:41.720]into the atmosphere and causing unstable conditions.
[00:48:44.020]Just like our drought risk here in Nebraska
[00:48:46.870]is highly tied to the central Rockies snow pack
[00:48:50.490]When it's well above normal, at 120% or greater,
[00:48:53.230]we generally don't have drought situation.
[00:48:55.700]When it drops below 80% of normal
[00:48:57.780]as we get into that late into that May period
[00:49:00.340]we generally have drought problems.
[00:49:02.160]So it's a key issue all the way along the front range
[00:49:05.100]of the Rockies.
[00:49:06.160]And of course, if you need to rush the fires
[00:49:07.970]to the West of us,
[00:49:09.710]the biggest situation is Southern Colorado
[00:49:12.000]through central Colorado in terms of dryness issues.
[00:49:15.170]And so these first winter snows have been highly unusual
[00:49:18.470]that they even made it down into that region.
[00:49:20.390]So they've actually benefited to some extent.
[00:49:23.880]Whether or not they can continue to benefit from it,
[00:49:26.720]statistical odds say no, late winter snow say possibly.
[00:49:32.330]And it's one thing in those regions
[00:49:34.000]when you get one of those big storms
[00:49:35.360]coming off of California,
[00:49:36.990]they can drop a tremendous volume of snow in a short order
[00:49:40.160]in the Southern Rockies
[00:49:41.220]and they can make up a lot of ground in short order.
[00:49:43.740]I would expect that they're still gonna come out
[00:49:45.440]below normal snow pack,
[00:49:47.260]but I suspect that it will be much improved
[00:49:49.620]over last winter, and that may help offset
[00:49:52.090]some of the drought getting started,
[00:49:54.870]re-emerging with intensity-wise
[00:49:57.500]in the early spring, early summer,
[00:49:59.100]and that may be a saving grace from us,
[00:50:00.880]allow us a little to escape this.
[00:50:02.920]But I really would watch that upper Missouri River basin
[00:50:06.150]because it will have the implications.
[00:50:07.730]If it continues this trend all winter
[00:50:10.160]we continue to see storm after storm in this region.
[00:50:12.670]Then we worry about where are we gonna store all that water
[00:50:15.820]particularly the second half of the summer
[00:50:17.860]as it starts to move its way down through Eastern Nebraska
[00:50:20.267]and toward the gulf.
[00:50:21.774](keyboard clicks)
[00:50:23.750]Very good.
[00:50:24.583]Anybody out there have questions for Al?
[00:50:26.800]We got him on the hook for a little little longer here, so.
[00:50:36.080]Sounds like cold and dry.
[00:50:38.370]Yes, but highly variable, remember that.
[00:50:41.360]Right.
[00:50:42.193]So basically what we're saying under the situation
[00:50:44.340]when you say highly a variable
[00:50:46.890]means we're gonna see frequent shifts from cold to warm,
[00:50:49.270]like we've seen,
[00:50:51.980]just the cold's gonna ween out in the long run.
[00:50:55.150]Intensity of the cold will be greater
[00:50:56.710]than the intensity of the warmth,
[00:50:58.350]and that's what we've seen these last three months.
[00:51:00.160]And I continue to believe that that will be the case
[00:51:02.050]going forward.
[00:51:04.730]This is AL Schoemaker.
[00:51:05.620]Is there a chance we could get a copy of the presentation,
[00:51:08.260]the slides? Absolutely.
[00:51:09.870]I will definitely send that to Megan
[00:51:11.330]as soon as I get off of this
[00:51:12.550]and then she can distribute it amongst everybody.
[00:51:16.790]You know, there's a lot of data there.
[00:51:17.820]It's nice to be able to refer back to it a bit
[00:51:19.880]during the year.
[00:51:21.490]And on top of that, I've also,
[00:51:23.870]some of these slides that appear in this
[00:51:25.790]particularly the La Nina, El Nino snowfall, temperature.
[00:51:29.850]and precipitation anomalies can also be found
[00:51:32.910]in my winter outlook article that was placed
[00:51:36.620]on the Nebraska State climate website
[00:51:39.140]under the news section.
[00:51:41.080]It has links to these articles that describe in full detail
[00:51:45.330]the process that unfolds with these temperatures
[00:51:47.860]and snowfall anomalies.
[00:51:49.480]So I will send this presentation
[00:51:52.180]and also try to enclose a link to that article
[00:51:56.830]that's on the NSCO site so if you wanna go
[00:51:59.280]and explore that detail, you can knock yourself out.
[00:52:02.320]If you don't, it won't be no skin off teeth.
[00:52:04.810]I just try to provide that as an extra incentive
[00:52:07.300]to kinda see what NOAA is doing.
[00:52:09.540]And this is the first time that we've had
[00:52:11.230]these types of snowfall anomalies.
[00:52:12.890]We've suspected these types of conditions,
[00:52:14.480]I've talked about them,
[00:52:15.800]but now we have some physical data behind them
[00:52:18.370]that does verify what we've seen in past instances
[00:52:20.970]of La Nina type snowfall patterns.
[00:52:26.900]All right, thanks for that Al.
[00:52:28.460]You bet.
[00:52:29.930]Anybody else?
[00:52:33.640]All right, good enough.
[00:52:34.780]All right, Megan, could you possibly give everybody
[00:52:38.470]kind of an intro to our next webinar?
[00:52:41.770]Absolutely.
[00:52:43.290]I've shared the link to register in the chat box.
[00:52:46.860]Registration is live for that.
[00:52:48.420]We'll meet again in two weeks
[00:52:50.450]at the same kind of lunch time,
[00:52:53.740]12:30 Central, 11:30 Mountain.
[00:52:56.290]And we have two County Highway Departments
[00:52:59.140]one from Iowa and one from South Dakota.
[00:53:02.030]So new to us Nebraskans that have been using social media.
[00:53:06.650]One uses Twitter more, the other one uses Facebook more.
[00:53:10.610]So we can see two different platforms
[00:53:12.670]to share about updates of their department
[00:53:16.800]and communicate with the traveling public.
[00:53:18.590]So maybe to...
[00:53:21.530]My goal for you in winter operations
[00:53:23.510]is maybe reduce a few of those calls that come in.
[00:53:27.570]When's the motor grader gonna get past my house?
[00:53:30.140]Well, if we can post some updates
[00:53:33.050]in a place people can find them,
[00:53:35.340]maybe that can make what's happening in your office
[00:53:37.920]a little bit easier.
[00:53:39.380]So I found two examples of regular County Highway Department
[00:53:45.370]that are doing that quite well.
[00:53:46.730]So we'll hear from them again, that's in two weeks,
[00:53:50.460]December 2nd at the same brown bag lunch time.
[00:53:56.319]All right, very good.
[00:53:57.660]Thanks again to Al and thanks to Megan
[00:53:59.900]for all the hard work that she's put
[00:54:01.920]into this webinar series,
[00:54:03.860]and we really hope to see everybody
[00:54:05.780]in a couple of weeks here.
[00:54:06.979]Thanks and.

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Winter Ops Webinars: Winter Weather Outlook for 2020/2021

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