Southeast Mid/Long Range Discussion III

[FoothillsNC]

looking for signs in the long range of a good pattern evolving from 00z runs..

You may have to watch late Friday night early Sat. The GFS keeps ever so slowly developing that southern wave in the Miss. Valley Friday and encounters some residual cold air, maybe damming for NW NC and sw VA after midnight. The trend lately has been to keep northwest flow in NC longer following the Wednesday front, so maybe its worth watching for ice, or even some flakes to ice to plain cold rain by early Saturday. This run definitely delays the warm up this weekend, esp. for the damming areas. Saturday looks miserable.

[BIG FROSTY]

You may have to watch late Friday night early Sat. The GFS keeps ever so slowly developing that southern wave in the Miss. Valley Friday and encounters some residual cold air, maybe damming for NW NC and sw VA after midnight. The trend lately has been to keep northwest flow in NC longer following the Wednesday front, so maybe its worth watching for ice, or even some flakes to ice to plain cold rain by early Saturday. This run definitely delays the warm up this weekend, esp. for the damming areas. Saturday looks miserable.

That's what I'm talking about. I still don't trust models with that big blowtorch, sure it's going to warm up, but it may not be as strong or long as modeled? I still have hope for feb and early march for a snow or two!

[FoothillsNC]

That's what I'm talking about. I still don't trust models with that big blowtorch, sure it's going to warm up, but it may not be as strong or long as modeled? I still have hope for feb and early march for a snow or two!

That should be it for the cold air though Fri/Sat. Right after that , southerly and sw winds kick in with much warm air for about everybody except the northwest and west. Well as soon as I had that ready to send the 192 and 216 panels came in and its much different than before. A big cold, full-lat trough moves across the country, and cools us down. The flow doesn't look sustained warmth as it did , atleast through 240.

[FoothillsNC]

This run is way different for the east coast especially. There was a close call in fact around 300 hour , where as before there was a huge ridge on the east coast, now its a trough, with a cutoff in Texas and more cold in the Ohio Valley. Overall this run has lots of waves everywhere instead of one massive ridge holding strong.

[packbacker]

This run is way different for the east coast especially. There was a close call in fact around 300 hour , where as before there was a huge ridge on the east coast, now its a trough, with a cutoff in Texas and more cold in the Ohio Valley. Overall this run has lots of waves everywhere instead of one massive ridge holding strong.

Pacific looks better at end of run too, the vortex has moved off AK, of course it's 350+ hours. Now we just need the Atlantic to cooperate.

[FoothillsNC]

It will be interesting to see how the ECMWF handles the pattern, and if it changes as much as this run did. The overall warmth esp. East coast got delayed and when we are warm, its pretty brief. I think there are too many s/w in the Pacific, so runs will be wildly different, esp. with that Ak. vortex spiraling system after system inland.

[FoothillsNC]

Pacific looks better at end of run too, the vortex has moved off AK, of course it's 350+ hours.

It had a deep west coast trough at the end of its run. Obviously the pattern will become very amplified soon, but it looks to favor western cold, eastern warm..but who knows it may be the opposite, thats so far out. Any change would atleast keep the chance for something alive, versus that 582 ridge that seemed to park near us for so long on the previous runs.

[Carvers Gap]

This run is way different for the east coast especially. There was a close call in fact around 300 hour , where as before there was a huge ridge on the east coast, now its a trough, with a cutoff in Texas and more cold in the Ohio Valley. Overall this run has lots of waves everywhere instead of one massive ridge holding strong.

The GFS has been waffling for about four straight runs. The Euro has been pretty consistent so I too will be interested in what it holds. It's tough to know where that model is going since it only goes to ten days. The 0z didn't look overly cold, and it didn't look overly warm. Looked a lot like what we've dealt w/ for a while. You know I was thinking today at lunch, you mentioned in the fall about the abnormal amount of cut-offs around the globe. I wonder if that might have been the clue to where this winter was heading - now seeing the previous six weeks unfold. The same steering currents that we need to send cold air south might be the allowing these cutoffs to spin-up? Don't know if there is even a correlation. Sometimes coming up w/ the right question is tough!

[andyhb]

That should be it for the cold air though Fri/Sat. Right after that , southerly and sw winds kick in with much warm air for about everybody except the northwest and west. Well as soon as I had that ready to send the 192 and 216 panels came in and its much different than before. A big cold, full-lat trough moves across the country, and cools us down. The flow doesn't look sustained warmth as it did , atleast through 240.

Several people on talkwx have expressed concern for a potential robust svr threat with this system, can't say I blame them with what a couple of the recent GFS runs have shown in this time period. Aggressive LLJ and substantial WAA northward across the Lower MS/TN valleys...

[FallsLake]

The 6z GFS also shows a colder pattern (compared to yesterdays). As Robert stated for the 0z there is defintily a back off on the warmth and a depiction of a big cool down at the end of the runs. Also like the 0z there seems to be a couple of "interesting" features. But I can not trust any of what the models are currently showing. Here's one "interesting" feature in the long range. The most important question here is not the potential storm but is the overall pattern right?

[burgertime]

The 6z GFS also shows a colder pattern (compared to yesterdays). As Robert stated for the 0z there is defintily a back off on the warmth and a depiction of a big cool down at the end of the runs. Also like the 0z there seems to be a couple of "interesting" features. But I can not trust any of what the models are currently showing. Here's one "interesting" feature in the long range. The most important question here is not the potential storm but is the overall pattern right?

Yep we need to hope for a solution like the 6z has at the end of it's run. It looked pretty good with all of the Eastern US in cold weather.

[FoothillsNC]

neither model looked as warm as it has been looking for a few runs. They keep a parade of systems going, we'll still be above normal overall.

[FallsLake]

RAH long range; maybe cooler highes for Saturday:

FRIDAY NIGHT THROUGH SUNDAY:

NEXT MORE SIGNIFICANT S/W TROUGH ALOFT IS EXPECTED TO AFFECT THE

AREA ON FRIDAY NIGHT INTO SATURDAY... POSSIBLY LINGERING INTO

SUNDAY. HOWEVER.. IT APPEARS THE BEST CHANCE OF SHOWERS SHOULD BE ON

SATURDAY. THUS... WILL CONTINUE CHANCE POPS FOR SATURDAY... WITH

SLIGHT CHANCE FOR FRIDAY NIGHT AND SATURDAY NIGHT THROUGH SUNDAY.

GIVEN THE EXPECT DRY AIR IN ADVANCE OF THIS SYSTEM WE MAY AT LEAST A

BRIEF PERIOD OF IN SITU DAMMING ACROSS THE AREA SATURDAY MORNING

INTO SATURDAY AFTERNOON. HOWEVER... IT APPEARS ALL PRECIP SHOULD

REMAIN LIQUID AT THIS TIME. GIVEN WE ARE TALKING ABOUT NEXT

WEEKEND... WILL NOT LOWER HIGH TEMPS GREATLY. FOR NOW WILL GO WITH

HIGHS MID 50S NW TO MID 60S SE ON SATURDAY... WITH HIGHS IN THE 60S

FOR SUNDAY (LOW CONFIDENCE IN OVERALL PATTERN BY SUNDAY THOUGH).

LOWS SATURDAY UPPER 30S NW TO MID 40S SE... WITH GENERALLY MID TO

UPPER 40S SUNDAY MORNING. -BSD

[Northern Foothills Snowman]

neither model looked as warm as it has been looking for a few runs. They keep a parade of systems going, we'll still be above normal overall.

I always enjoy reading your post .Good,cold and snowy, or bad,like what we have been having this winter, they are always informative.I'm wondering what's the latest on the second strat warming?Also what will it take to shake up.chage this pattern we seem to be stuck in?

[Brick Tamland]

Seems the pattern of cooling down for a couple of days, then warming up and having a shot of rain, then repeating continues this week. But with a high near 70 Sunday at the end of January, I pretty much have to say this winter is going to end early.

[GreensboroWx]

Long range GFS ensembles indicating a developing -NAO.....could be a bit premature, but it's worth noting. Also, it has a neutral to slightly positive PNA developing.

Now the ECMWF is not quite the same, so the model wars continue.

I think the warm spell won't be quite as strong or long as previously indicated, so all is not lost yet.

[WinterWonderland]

I thought this was interesting info from Wunderground . . .

Posted by: JeffMasters, 4:06 PM GMT on January 06, 2012 +37

Flowers are sprouting in January in New Hampshire, the Sierra Mountains in California are nearly snow-free, and lakes in much of Michigan still have not frozen. It's 2012, and the new year is ringing in another ridiculously wacky winter for the U.S. In Fargo, North Dakota yesterday, the mercury soared to 55°F, breaking a 1908 record for warmest January day in recorded history. More than 99% of North Dakota had no snow on the ground this morning, and over 95% of the country that normally has snow at this time of year had below-average snow cover. High temperatures in Nebraska yesterday were in the 60s, more than 30° above average. Storm activity has been almost nil over the past week over the entire U.S., with the jet stream bottled up far to the north in Canada. It has been remarkable to look at the radar displayday after day and see virtually no echoes, and it is very likely that this has been the driest first week of January in U.S. recorded history. Portions of northern New England, the Upper Midwest, and the mountains of the Western U.S. that are normally under a foot of more of snow by now have no snow, or just a dusting of less than an inch. Approximately half of the U.S. had temperatures at least 5°F above average during the month of December, with portions of North Dakota and Minnesota seeing temperatures 9°F above average. The strangely warm and dry start to winter is not limited to the U.S--all of continental Europe experienced well above-average temperatures during December.

Figure 1. Flowers sprouting on January 1, 2012 in Keene, New Hampshire, thanks to unusually warm December temperatures and lack of snow. Image credit: Wunderphotographer lovne32.

Figure 2. Departure of snow depth from average on January 6, 2011. More than 95% of the country that normally has snow at this time of year had below-average snow cover (yellow and orange colors.) Image credit: NOAA/National Operational Hydrologic Remote Sensing Center.

December 2011 jet stream pattern the most extreme on record

The cause of this warm first half of winter is the most extreme configuration of the jet stream ever recorded, as measured by the North Atlantic Oscillation (NAO). The Arctic Oscillation (AO), and its close cousin, the North Atlantic Oscillation (which can be thought of as the North Atlantic's portion of the larger-scale AO), are climate patterns in the Northern Hemisphere defined by fluctuations in the difference of sea-level pressure in the North Atlantic between the Icelandic Low and the Azores High. The AO and NAO have significant impacts on winter weather in North America and Europe--the AO and NAO affect the path, intensity, and shape of the jet stream, influencing where storms track and how strong these storms become. During December 2011, the NAO index was +2.52, which was the most extreme difference in pressure between Iceland and the Azores ever observed in December (records of the NAO go back to 1865.) The AO during December 2011 had its second most extreme December value on record, behind the equally unusual December of 2006. These positive AO/NAO conditions caused the Icelandic Low to draw a strong south-westerly flow of air over eastern North America, preventing Arctic air from plunging southward over the U.S. and Europe.

Figure 3. December 2011 temperatures in Europe and the U.S. were well above average, thanks to a positive phase of the Arctic Oscillation (AO). Compare the U.S. plot with the plot of typical departures of temperature from average due to the positive phase of the AO (Figure 4.) The two patterns are nearly identical. Image credit: NOAA/ESRL.

Figure 4. The departure of temperature from average in Centigrade during the November - December - January period during various phases of the Arctic Oscillation (AO). Positive AO conditions lead to warm winters in the U.S., while negative AO conditions lead to cold winters. Image credit: NOAA/Climate Prediction Center.

Wild swings in the December Arctic Oscillation

This winter's remarkable AO/NAO pattern stands in stark contrast to what occurred the previous two winters, when we had the most extreme December jet stream patterns on record in the opposite direction (a strongly negative AO/NAO). The negative AO conditions suppressed westerly winds over the North Atlantic, allowing Arctic air to spill southwards into eastern North America and Western Europe, bringing unusually cold and snowy conditions. The December Arctic Oscillation index has fluctuated wildly over the past six years, with the two most extreme positive and two most extreme negative values on record. Unfortunately, we don't understand why the AO varies so much from winter to winter, nor why the AO has taken on such extreme configurations during four of the past six winters. Climate models are generally too crude to make skillful predictions on how human-caused climate change may be affecting the AO, or what might happen to the AO in the future. There is research linking an increase in solar activity and sunspots with the positive phase of the AO. Solar activity has increased sharply this winter compared to the past two winters, so perhaps we have seen a strong solar influence on the winter AO the past three winters. Arctic sea ice loss has been linked to the negative (cold) phase of the AO, like we observed the previous two winters. Those winters both had near-record low amounts of sunspot activity, so sea ice loss and low sunspot activity may have combined to bring a negative AO.

Figure 5. The December Arctic Oscillation (AO) index has fluctuated wildly over the past six years, with the two most extreme positive and two most extreme negative values on record. Image credit: NOAA/Climate Prediction Center.

The forecast for the remainder of January

We will (finally!) get the first major storm of 2012 in the U.S. early next week, when a low pressure system will develop over Texas and spread heavy rains of 1 - 3" along a swath from Eastern Texas to New England during the week. This storm will pull in a shot of cold air behind it late in the week, giving near-normal January temperatures to much of the country, and some snow to northern New England. Beyond that, it is difficult to tell what the rest of winter may hold, since the AO is difficult to predict more than a week or two in advance. The latest predictions from the GFS model show the current strongly positive AO pattern continuing for at least the next two weeks, resulting in very little snow and warmer-than-average temperatures. If we don't get significant snows during the latter part of winter, the odds of a damaging drought during the summer in the Midwest will rise. The soils will dry out much earlier than usual without a deep snow pack to protect them, resulting in a much earlier onset of summer-like soil dryness. Water availability may also be a problem in some regions of the west due to the lack of snow melt. Fortunately, most Western U.S. reservoirs are above average in water supply, due to the record-breaking snows of the previous winter.

Jeff Masters

Categories: Winter Weather

[burgertime]

Long range GFS ensembles indicating a developing -NAO.....could be a bit premature, but it's worth noting. Also, it has a neutral to slightly positive PNA developing.

Now the ECMWF is not quite the same, so the model wars continue.

I think the warm spell won't be quite as strong or long as previously indicated, so all is not lost yet.

That will be the ticket, just sucks that the Euro isn't joining in. Now the question will be if we can get those telecommunications in our favor does the lack of snow pack hurt the really cold air from filtering in? I don't know anything about snow pack and how important it is since there is so many varying opinions on it.

[Poimen]

The 8-14 day 500mb analogs have some interesting years. Most notable 1980 and 1993, both of which produced late season widespread southern snow storms. It proabbly does not mean much at all, but something to consider as we wait for winter to arrive.

[tarheelwx]

That will be the ticket, just sucks that the Euro isn't joining in. Now the question will be if we can get those telecommunications in our favor does the lack of snow pack hurt the really cold air from filtering in? I don't know anything about snow pack and how important it is since there is so many varying opinions on it.

I beleive snowpack to be critical when it comes down to surface temps and with CAD. It really doesn't impact whether we have frozen or liquid precip. Having said that, it is always nice to have the snowpack as it keeps surface temps a few degrees colder which impacts how much sticks, and in zr situations, how cold it is at onset and how long the freezing temp hangs on (if cold air advection from over snowpack it can run a degree or two colder than without. If no advection as the event unfolds, it could just give you a colder point to begin the warmup from, meaning a longer period of zr, but still warming to 33).

TW

[Rankin5150]

For a lot of the people in the Southeast region that are either transplants (lets say from 1990 to date) or are young enough to not remember some winter storms (from this region) in the 70's and 80's, then I will say that we can have a VERY Significant to histioric winter storm after much above normal temperatures. I remember before the 1988 storm (or it may be another year) the weather was VERY WARM, HIGH ABOVE NORMAL Temps in the days leading up to the storm. That night, the cold front rushed in (from a strong clipper) and we got hammered with 12"+ of snow. The weather stayed cold for a few days afterward and then went back to warm. Just saying...I am leaving the glass "half full".

[weatherheels]

You may have to watch late Friday night early Sat. The GFS keeps ever so slowly developing that southern wave in the Miss. Valley Friday and encounters some residual cold air, maybe damming for NW NC and sw VA after midnight. The trend lately has been to keep northwest flow in NC longer following the Wednesday front, so maybe its worth watching for ice, or even some flakes to ice to plain cold rain by early Saturday. This run definitely delays the warm up this weekend, esp. for the damming areas. Saturday looks miserable.

Looking like the GFS is sticking with this idea. Verbatim the temps arent quite cold enough, but as you can see the High pressure placement is pretty decent for some cad. If this could trend a little stronger, possible a bit further south, its not out of the realm some spots in favorable damming areas will be below freezing before it warms up. Seems this would probably start off as snow or zr like you said in the mountains. Im heading up to Beech this weekend, so hopefully this system will produce a little snow up there at the onset.

[Psalm 148:8]

Rankin,do you remember a snow around Easter during the very late 70s-80s? I went to grandmas (who lives in your town) and there was snow on the ground here in Georgia when we left home and the minute I got to her house there was enough snow to build a snowman. Wish I could remember how old I was...maybe dad or gramdmother remembers.

[FallsLake]

Looking like the GFS is sticking with this idea. Verbatim the temps arent quite cold enough, but as you can see the High pressure placement is pretty decent for some cad. If this could trend a little stronger, possible a bit further south, its not out of the realm some spots in favorable damming areas will be below freezing before it warms up. Seems this would probably start off as snow or zr like you said in the mountains. Im heading up to Beech this weekend, so hopefully this system will produce a little snow up there at the onset.

This does look interesting. It's going to come down to how well placed the high is, how strong it is, how cold/dry the air source, and of course the precip. We are within five days so, I think this could be a real possibility. Robert? and other met?

[Brick Tamland]

Allan Huffman made a good point in his blog today. It's hard to say winter is over when it really hasn't even started yet. Maybe this winter will just have a start late and February will be the beginning. It looks like this warm up this weekend and next week won't last long.

http://www.examiner.com/weather-in-raleigh/after-a-preview-of-spring-for-end-of-january-colder-pattern-likely-for-february

[snowman22]

I remember my grandma telling me about snow in April 1987 I think? What were the conditions like that winter? I think she said it snowed all the way down to Greenville, Al where she has lived since the 50s.

[Pathfinder]

I remember my grandma telling me about snow in April 1987 I think? What were the conditions like that winter? I think she said it snowed all the way down to Greenville, Al where she has lived since the 50s.

That was April 4-5, 1987, I lived in Southwest VA at the time, it was a large snow by any standards but was even more impressive considering it was in April.

Edit:

Here's a thread on that storm in the main weather section:

[burgertime]

12Z looks much better in the LR...of course brings in front after front which chases the moisture away only to bring in freezing temps...we might get lucky on one. Either way it does look like there is light at the end of the tunnel and it isn't the freight train jburns mentioned!

[tnweathernut]

Don't have time to look, but is the long range GFS still advertising a -NAO? What about the PNA? Thanks in advance for anyone willing to discuss.

[packbacker]

Don't have time to look, but is the long range GFS still advertising a -NAO? What about the PNA? Thanks in advance for anyone willing to discuss.

Yes, the +PNA has been there on the past couple of run in the LR, today was the first day I noticed a hint of a -NAO at the end of the run, although would like a met to confirm. The AO still looks positive but the AK vortex is starting to weaken and get shunted east. Granted it's 300+ hours out but I guess it's good that it's showing changes. I am not buying in until the Euro agrees.