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2018-2019 Winter Discussion


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Both the Euro and GFS "see" some winter precip for Friday/Saturday, but temps don't really support snow at the moment. But hey... let's roll with it. ūüôā NOT A FORECAST

I know everyone is really tired of the warm (but pretty normal) weather we've had for part of December. I do understand.  I won't talk about how this was pretty much in every forecast, because I

Have you just come here to troll or what? You keep arguing about anything actually happening, but when Steve responds with data and models, you just roll over and say you don't know what that means. U

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I agree, no need to be rude and we've had this discussion before. It doesn't matter if I make a positive post, you will come back with a negative reply. I share information from the most knowledgeable people in the business, and during times like this, it is their opinions and thoughts that you have to go with. If you have a problem with the message, you need to share it with them. I know that there are a LOT of people here and on the Facebook page that aren't happy with this weather, I get it, I understand. And I'm sure they would love to complain as well, but they also know that accomplishes nothing here. 

I'm trying to show you everything that's going on in the background so that you'll be better informed as to what (and why) might happen. I don't make a forecast but I will tell you what I think, however there is one thing I know for a fact... there is no certainty when it comes to weather. The atmosphere is a chaotic non-linear environment, so trying to make a forecast out of chaos is seriously challenging. 

If you knew what MANY of the forecast called for, you wouldn't be questioning what's going on as much. Many of them had a warm December and didn't have it getting cold until mid-January. Models are NOT the gospel, and it's not as simple as going to look at an operational model run, not seeing any cold, and saying "no cold in sight". There are so many other things to be looking at right now. The models struggle mightily during times when patterns are starting to change. But it does appear that they are just now starting to show changes in the 500 mb patterns due to the SSW. 

It's not simple or easy, and there is no magic button to press to make things happen. Be patient and watch things unfold.

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4 minutes ago, NorthGeorgiaWX said:

I agree, no need to be rude and we've had this discussion before. It doesn't matter if I make a positive post, you will come back with a negative reply. I share information from the most knowledgeable people in the business, and during times like this, it is their opinions and thoughts that you have to go with. If you have a problem with the message, you need to share it with them. I know that there are a LOT of people here and on the Facebook page that aren't happy with this weather, I get it, I understand. And I'm sure they would love to complain as well, but they also know that accomplishes nothing here. 

I'm trying to show you everything that's going on in the background so that you'll be better informed as to what (and why) might happen. I don't make a forecast but I will tell you what I think, however there is one thing I know for a fact... there is no certainty when it comes to weather. The atmosphere is a chaotic non-linear environment, so trying to make a forecast out of chaos is seriously challenging. 

If you knew what MANY of the forecast called for, you wouldn't be questioning what's going on as much. Many of them had a warm December and didn't have it getting cold until mid-January. Models are NOT the gospel, and it's not as simple as going to look at an operational model run, not seeing any cold, and saying "no cold in sight". There are so many other things to be looking at right now. The models struggle mightily during times when patterns are starting to change. But it does appear that they are just now starting to show changes in the 500 mb patterns due to the SSW. 

It's not simple or easy, and there is no magic button to press to make things happen. Be patient and watch things unfold.

Alrighty sounds good.

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15 minutes ago, LoveSnow said:

This is my first year actually 

Maybe some of the folks that have followed me on Facebook for years, can tell you about me and the local mets. You will rarely hear about events very far out in the future from them, so you will hear it here before they mention it. And some of that are station policies that prevents them from saying certain things depending on management. The point is, they might see it too but are restricted in talking about it.

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Steve, your doing a awsome job by keeping us informed esspically me. I read your blog every morning. And I'm sorry other are being rude or think your God and can make weather happen.but your not. And the thing about the weather men and women on tv. They only talk¬†about weather 5 to 7 days out. So something king range as the cold weather coming or ETC. You will only hear about it just a few days out.¬† So for all the people who are being negative. Just relax. And let the weather happen. Becuase I find it very interesting to see what's in store. What could happen and what wont happened. Winter is only 10 daya old. We have 2 1/2 months left of winter. Plenty of time to let "Winter" happen. We all know for the ones who live in Ga. It can be 70¬į with severe storms 1 day and wake up the next morning with 2 inches of snow on the ground...

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Here is some updated information about the SSW. It now appears that this may end up being classified as a Major SSW, meaning that in addition to the rapid increase in temperatures, the 10 hPa winds will completely reverse direction. I will also say that the models are increasingly showing a  -AO/-NAO/+PNA and the GEFS takes them both the AO and NAO extremely negative, possibly in response to the data from the stratosphere. 

These images from Zac Lawrence's site from the GOES-5 and GFS show the strat PV being split into multiple vorticies.  

Snap346062185-30.thumb.jpg.0cac7e0d2219d9ebbf6d54d3669a053d.jpg

Snap346062184-30.thumb.jpg.94e130003ddd4283bac7827323b3bd6c.jpg

 

The Euro shows the same thing, and all show the two main pieces of the vortex residing over Siberia and North America. ( http://www.daculaweather.com/4_stratosphere_temp_ecmwf.php )

ecmwf10f144-30.gif.25b3c2c1fe114c4d022466eca75c90b2.gif

 

Here you can see the westerly winds go easterly. ( http://www.daculaweather.com/4_strat_details.php )

time_pres_UGRD_MEAN_OND_NH_2018-30.png.60981e805d54d8d68543ec95c4969c77.png

 

And another cross section image of the warming ( http://www.daculaweather.com/4_strat_details.php )

time_pres_TEMP_ANOM_OND_NH_2018-30.png.17093c3aa12e72f7ff879d15042a48c5.png

 

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Larry Cosgrove

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"It is all there. So what could possibly be wrong ?" is the famous question that many in the weather prediction business are asking. There is a complete evacuation of colder values at the highest levels of the atmosphere, which should predispose vortex suppression into lower latitudes and create opportunities for amplified ridging around the Arctic Circle. The subtropical jet stream is sinking to its southernmost positions since 2008. Analog scenarios point toward a sharp turn into much colder values like the winter of 2014-2015. Remember the cold "Snowvember", milder December, and major turn toward Arctic air that did not let go into mid-March? And just look at that pulsing Madden-Julian Oscillation, which is intense, very broad, and showing signs of linking with the polar westerlies and forming an Aleutian Low.

All of these indicators would seem to point out that we are in for a coming turn to widespread cold and snow across the eastern two-thirds of the U.S. after a relatively mild December. But the problem that we are facing comes from the ECMWF ensemble platform, which takes its very warm operational version into even warmer territory as we advance into mid-month! The variant members disagree rather violently with its own weeklies and monthlies. This scheme is valued as a medium range prediction (sometimes wrong, but that is a story for another time), but I look at its recent quick abandonment of a cold period as cause for concern. Could it really introduce widespread mild air? And remember, the model series is NOT showing a true "January Thaw" (lots of rain east of the Rocky Mountains, and a wipe-out of the snowpack). Something is wrong here, and cries out for extreme examination of the longer term outlook.

I have continually mentioned that the GGEM ensemble members has been the most consistent with its upper air configuration. Highly amplified, but still progressive. Showing a colder turn, but not to any extreme. The GFS series looks somewhat similar to the ECMWF group, although displaying a mostly cold eastern states solution. One card to play in the forecast is the El Nino, which remains in weak strata and seems increasingly based over the western Pacific Basin (note the cooling along the coastline of South America). With the already out-of-position subtropical jet stream, the storm track will at some point this month likely trend to follow the Gulf Coast and Eastern shoreline like it did last month. If the analog means are correct, the U.S. may actually have a harsh winter to deal with in later January through February, with stronger ridging in Alaska, northern Canada and Greenland.

But for now, we wait....
 
Prepared by Meteorologist LARRY COSGROVE on 
Saturday, December 29, 2018 at 10:45 P.M. CT

 

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9 hours ago, firefighter556 said:

Sorry to ask.  But what does this mean? Lol

What all of the strat warming means is that now that the models can better see the magnitude of it (and it's still ongoing), they can start to see impacts at the surface. The models are going to be VERY volatile for several weeks as they try to get a grasp on what's going on, so expect to see big swings in models runs, models not jiving with other models, and even models not jiving with themselves. 

Cold is coming...

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I know everyone is really tired of the warm (but pretty normal) weather we've had for part of December. I do understand. 

I won't talk about how this was pretty much in every forecast, because I know you don't want to hear it now, so instead I'll talk about what I see going on and why I believe that we are entering a very exciting time.

I am excited about the upcoming period. When I say period I mean from basically now through the end of February. There are going to be some exciting times ahead as we progress into a volatile winter pattern. Think about this. None of the winter forecast had an early season Major SSW, yet almost all forecast showed a cold winter with above normal snowfall. Now you add the affects from a major event like this SSW on top of everything else that's going on, and you have a recipe for a winter to remember. 

Keep in mind, the models are not infallible and are sometimes VERY wrong in what they show. Even the highly touted Euro fails. The main thing for the moment is don't bother looking past 5 days at any of the operational models... they are going to be wrong for now. Think about it this way. If I throw one pebble in a calm pond, it's going to be easy to predict the wave motion. If I throw 50 in a once, how hard do you think that will be to predict? It's no different with weather. If the patterns are relatively stable, the forecast accuracy will be high, once the pattern gets volatile, the accuracy goes down. The more variables you throw in to the mix, the tougher it gets. Most of the time, the stratosphere has little practical impact at the surface, but in the winter during SSW's, it can have a MAJOR impact, and the models struggle with how to handle that. There is a limited amount of stratospheric data for the models to use in generating forecast and even less certainty on the practical affects at the surface, so the models end up all over the place. 

But here is what I'm looking for. The first thing I want to see are the signs of the high latitude blocking, and that will flip around for a while. Start looking at the teleconnection patterns. Do you want to see what major high latitude blocking looks like? 

This is the GFS ensembles from the last run yesterday, and this is the Arctic Oscillation (AO). When the AO goes negative, it means that the PV has been displaced from the polar region and instead replaced by high pressure. If the PV is displaced, so is the cold. Notice the extreme dive in the index. 

  • Arctic Oscillation (AO)

gefs_ao_18-31.png.6930a6f91564e9849954b91776dfa63c.png

 

And this is the general result

ao_neg.thumb.png.c2f0daf8f6cb2ef6f3703b2501467009.png

In case you'd like more information, take a look at my Arctic Oscillation page for more information

http://www.daculaweather.com/4_ao_index.php

 

  • North Atlantic Oscillation (NAO)

There is one more piece that we need in terms of blocking, and that's a negative NAO, and again, the last run from the ensemble yesterday took that deeply negative as well. More information on my NAO page 

http://www.daculaweather.com/4_nao_index.php

gefs_nao_18-31.png.82b0f34ffd23d172877a09f725dba4ee.png

nao_neg.thumb.png.4c4e4a624c76f1b7b76846be48ca1a68.png

 

  • East Pacific Oscillation (EPO)

But wait! ūüôā¬†There is another block piece that we need... a negative EPO. Without the -EPO, the continental US gets flooded with warm Pacific air. Not good. So we want to see a negative EPO. Again, the ensemble run from yesterday as well as a link to my EPO page and a colorful example. ūüôā¬†Notice the extreme step-down of the EPO.¬†

gefs_epo_18-31.png.ac2d9fdb128b6a0c3f812f6800687d0b.png

epo_neg.thumb.png.e17d2bce762fd966a700b22b419e8945.png

 

So the point is, you have to look past the everyday models and look at the bigger picture. I know I've posted a lot about the strat warming, but that is because of the potentially significant effects it will have on our winter. It is the "amplifier" to what was going to happen to start with, and those original winter forecast were for a pretty good winter. So add all of these things together, and we should be in for a great Jan/Feb period.

So hang in there... if I'm excited, you should be excited as well!

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