December and January Pattern Discussion

[Carvers Gap]

Wow. The 0z Euro shows some major NE coastal lows. I can't tell much in terms of precip types for here. It does show major cold in between systems though. Has been the most consistent lately in showing the trough in the east....

[John1122]

The 00z GFS was blisteringly cold for the midwest in the LR, I doubt it happens to quite that extreme, but it'd be impressive. The best thing about it, it moves the cold into the Tennessee Valley and leaves Florida and the SE coastal areas as practically the only warm spots left in the country.

 

The midwest, and even as far as S. Missouri would spend days in the single digits for highs or even colder and even that level of cold approached Tennessee at the end of the run.

 

The cold is on our side of the globe for a change this winter, and the models keep trying to find ways to let it expand south and east. We'll see if one of them will finally actually stick. I have a hard time believing it's not going to come down at some point this winter.

[John1122]

Heh, and the 06z dumps the Arctic into the Intermountain West and spreads it eastward much more slowly than the 00z did. The 06z is literally almost 55 degrees warmer in some places during the same timeframe from the 00z. It still delivers the massive Arctic blast, but it goes from having it arrive in around 200 hours, to delaying it to 272-288 hrs. 

 

It also buries the entire Tennessee valley with a beautiful fantasy storm in the la la land extended.

 

The only thing I actually take out of it at all is that maybe the cold is coming, and this time, it's maybe going to be driven all the way into the central Carolina region instead of into the western half of the TN Valley region. I just would love to see it climb into the 180 or less range soon.

 

In the nearer term, it's showing some potential for maybe 1/2 to 1 inch of snow for the general upslope regions this Thursday night and Friday.

[John1122]

From the 00z Euro Op. I sorely wish that ridging in the N. Atl was about 400 miles west of there, nosing into Greenland.

 

[Stovepipe]

Heh, and the 06z dumps the Arctic into the Intermountain West and spreads it eastward much more slowly than the 00z did. The 06z is literally almost 55 degrees warmer in some places during the same timeframe from the 00z. It still delivers the massive Arctic blast, but it goes from having it arrive in around 200 hours, to delaying it to 272-288 hrs. 

 

It also buries the entire Tennessee valley with a beautiful fantasy storm in the la la land extended.

 

The only thing I actually take out of it at all is that maybe the cold is coming, and this time, it's maybe going to be driven all the way into the central Carolina region instead of into the western half of the TN Valley region. I just would love to see it climb into the 180 or less range soon.

 

In the nearer term, it's showing some potential for maybe 1/2 to 1 inch of snow for the general upslope regions this Thursday night and Friday.

 

Congrats to Memphis on 9 inches of fantasy snow!  They win the clown map of the day award.

[Carvers Gap]

12z GFS is rolling. Jan 3-4 threat has returned to a previous solution with what appears to be a partial phase. True, it is juts one possibility, but at 96 hrs cannot be totally discounted...though the GFS and other operational models have been somewhat erratic. HPC had a great write-up in the extended. We will see if it is supported by its ensemble. Edit: In trying to figure out what would force this system south, looks like the HP to the north is the driver on this run.

[tnweathernut]

Don't sleep on the event around the 6th, especially those in west and middle TN.  The depiction is a classic arctic wave that moves ENE and a rain to snow changer on the backside of a rather juicy low.  We haven't had many of those in the last 25 years, but it's a realistic depiction of what could happen. 

 

One other thing I noticed was the placement of low pressure is quite a bit further south on 0z from yesterday's 12z Euro run.  Perhaps an early trend...............Push it a little further south and it's a much bigger deal for many across TN. 

 

As it is now, the text data prints out over .65 for BNA (mostly snow after .25 or so of cold rain)

[Stovepipe]

Latest Don Sutherland thoughts for those that might not check the main board often.

 

 

Not by Teleconnections Alone…

 

For North America, the possibility of one or two bouts of severe to extreme cold to open the first 7-10 days of January appears increasingly likely. Whether or not the 12/29 12z and 12/30 0z ECMWF’s idea of 1985- or 1994-style Arctic outbreaks verifies, the proverbial die has been cast that much of Canada, along with a large part of the eastern half of the CONUS will likely wind up colder than normal.

 

With blocking developing—the AO has now been negative for two consecutive days—one should typically expect to see cold develop over parts of Europe where temperatures have been downright toasty. Indeed, Muscovites have sweated through a November that averaged almost 8°F above normal and December appears poised to finish at least as warm. Certainly, if one runs the maps for the forecast teleconnections, one sees a colder outcome.

 

However, after a close look at the details beyond the teleconnections, the colder outcome appears unlikely. The persistent EPO- has led to an outcome in which almost all of the Northern Hemisphere’s anomalous cold has drained into North America. The EPO- regime is likely to persist for the foreseeable future. As a result, very little anomalous cold will be available to be tapped for Europe despite what would typically be the development of a favorable synoptic pattern for cold.

 

Below are maps illustrating global cold anomalies for December 29, 2013; the December 1-28, 2013 timeframe for the Northern Hemisphere, and those for Decembers 1984 and 1993 for the Northern Hemisphere. Maps for the forecast teleconnection indices and January 1994 are also included.

 

 

December 1984 saw widespread cold anomalies in the Northern Hemisphere. December 1993, not unlike December 1-28, 2013 featured less expansive cold anomalies centered near North America. January 1985 wound up very cold across much of North America and also Europe. In contrast, North America experienced cold anomalies in January 1994, while much of Europe wound up warmer than normal.

 

If one looks at the CFSv2’s forecasts since 12/20 (the beginning of its more skillful range), one finds a consistent theme of warmth in Europe. The GFS ensembles and ECMWF ensembles also indicate generally mild conditions through their extended range, with the GFS ensembles bringing about some cooling, particularly in southern Europe, Scandinavia, and extreme Western Europe at the end of their range. The 12/30 0z run of the ECMWF produces anomalies very similar to the January 1994 map by 240 hours.

 

In short, it appears that January 2013 could have warm anomalies centered near where they were centered in January 1994. The northern half of Scandinavia might wind up on the cool side of normal. Northern Africa and the Mideast might wind up near normal with perhaps some cool anomalies in the Mideast. But overall, one won’t see the kind of widespread cold one saw in January 1985 despite what the teleconnection indices might imply.

[John1122]

Does anyone want to start a thread for the Jan 2nd-3rd timeframe, or possibly at least keep it in the upcoming events section? We suddenly have several potential events to track and under 100 hours on the event this week is getting into the short range.

[jmundie]

Don't sleep on the event around the 6th, especially those in west and middle TN.  The depiction is a classic arctic wave that moves ENE and a rain to snow changer on the backside of a rather juicy low.  We haven't had many of those in the last 25 years, but it's a realistic depiction of what could happen. 

 

One other thing I noticed was the placement of low pressure is quite a bit further south on 0z from yesterday's 12z Euro run.  Perhaps an early trend...............Push it a little further south and it's a much bigger deal for many across TN. 

 

As it is now, the text data prints out over .65 for BNA (mostly snow after .25 or so of cold rain)

 

 

Ukie gives us some love on the SLP placement (edit - this is for day 4, not day 8 threat)

 

[valkhorn]

 

 

 

[tnweathernut]

^{Larry was saying a Miller A all along.............will be interesting to see if he was on to something.}

 

^{Larry Cosgrove}

^{12z operational GFS has shifted to a Miller "A" scenario, seems to be trending toward the ECMWF idea of a significant snow event for the Mid-Atlantic and New England states. With lots of wind and cold, too, for the January 2 - 4 period.}

[tnweathernut]

This caught the eye of Robert at WxSouth too.  Interesting.

WxSouth

It's pretty interesting just how often Southwest lows have held together this season. The last few days I dropped my idea and went with the models, in allowing that southwest system to not hold together. Now the models are all trending toward what has usually happened--that is, a storm in the Gulf. Should have stuck with my initial leaning. The European, GFS , NAM are all leaning this way now, after dropping that idea. This isn't a done deal yet, but the trend is what is important. This will make for close call rain/snow lines in northern Alabama, eastern Tennessee, western NC, and eventually into Virginia and DC, Maryland on Thursday . This could trend into something pretty substantial from the mountains of TN/NC north and eastward up the East Coast. We'll see how the European Model handles it soon.

[Stovepipe]

Does anyone want to start a thread for the Jan 2nd-3rd timeframe, or possibly at least keep it in the upcoming events section? We suddenly have several potential events to track and under 100 hours on the event this week is getting into the short range.

 

Nut should start the thread.  This is his baby, he needs to reel it in. 

[Stovepipe]

12z Euro looks insanely cold by hour 168, wow.

[tnweathernut]

If this run of the Euro is to be believed, Nashville and points west will have 6-12 inches of snow on the ground and single digit weather by Jan 6/7th.  We again saw more consistency centered around the Jan 6th timeframe with regards to something big.  The 850's were colder and the entire system was a bit further south and east.  Nice little trend going on for that system even though I have ZERO illusions of it being something we can count on this far out.  Time will tell, but I hope someone gets plastered!

[Stovepipe]

[BullCityWx]

If this run of the Euro is to be believed, Nashville and points west will have 6-12 inches of snow on the ground and single digit weather by Jan 6/7th.  We again saw more consistency centered around the Jan 6th timeframe with regards to something big.  The 850's were colder and the entire system was a bit further south and east.  Nice little trend going on for that system even though I have ZERO illusions of it being something we can count on this far out.  Time will tell, but I hope someone gets plastered!

 

Yep. Pulling for y'all!

[BullCityWx]

Foot of snow easy for places like Nashville/Memphis. Knoxville would probably see 6"+, too. 

[jmundie]

no words.

[tnweathernut]

Yep. Pulling for y'all!

Thanks Queencitywx, although it mostly misses my area KTRI, I am pulling for the guys west of here.  Nashville has been in a multi decade snow drought like no one else in the last 25 years!

[Carvers Gap]

12z Euro. Both 96 and 168 look very good for varied points in the TN Valley. Looks like two events to track. Will be interesting if one weakens the other. Anyway, the low at 168...I will take it even though the precip is not there yet. Great run for a new WX region.

[tnweathernut]

no words.

Not to add insult to injury, but my synopsis of the cold air following the 12z euro is wrong, you'd have lows in the 20 BELOW range, not single digits........Too cold to play in??  lol

[jmundie]

Not to add insult to injury, but my synopsis of the cold air following the 12z euro is wrong, you'd have lows in the 20 BELOW range, not single digits........Too cold to play in??  lol

 

 

I'll take 20 below. I was 4 months old in 85, so never got to experience it. I just love extreme weather.

[John1122]

Tri-Cities still gets 3-6 inches on the Euro. Nashville is well into double digits, Knoxville is also in the 3-5 range. Really, the whole state except the Chattanooga area gets pretty well hammered that run. Some areas just get epic amounts. 

[John1122]

That would be the overall coldest weather ever experienced for most of Tennessee and the Eastern part of the country. It appears to have an area of -30s over Campbell County. The last wide spread double digit below 0 stuff in Tennessee was 1996. And even then it was limited to the Plateau, Northern Valley and Mountains. -5 to -8 in the lower elevations that time. This would be moderately colder. You'd see the old 1985 type travel warnings.

 

I did notice that MRX didn't peep about this at all in their afternoon AFD. Just said warmer weekend. They didn't really say much about the Jan 2nd system either. Of course they're literally the least descriptive AFO in the country when it comes to their forecast thoughts.

[jaxjagman]

Text on the Euro shows for TYS for the 3rd .34, qpf on the 6th ...88 qpf..For BNA..on the 3rd..36 qpf.. 1.08 the 6th..all snow

[franklin NCwx]

Euro ensembles match the op for both storms

[jaxjagman]

PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS

NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD

300 PM EST MON DECEMBER 30 2013

6-10 DAY OUTLOOK FOR JAN 05 - 09 2014

TODAY'S ENSEMBLE MEAN FORECASTS ARE IN GOOD AGREEMENT ON THE EXPECTED 500-HPA

HEIGHT PATTERN FOR THE 6-10 DAY PERIOD OVER NORTH AMERICA. ENSEMBLE MEANS FROM

THE ECMWF, GEFS, AND CANADIAN ENSEMBLES AGREE ON THE PREDICTION OF A 500-HPA

RIDGE EXTENDING FROM JUST OFF THE WEST COAST OF THE CONUS TO CENTRAL ALASKA.

MODELS AGREE ON BELOW-NORMAL HEIGHTS IN A BROAD TROUGH PREDICTED TO BE OVER THE

MIDDLE MISSISSIPPI VALLEY EXTENDING NORTHWARD TO HUDSON BAY. THE DETERMINISTIC

RUNS OF THE GFS SHOW SOME SIGNIFICANT DIFFERENCES IN THE PREDICTED TROUGH AXIS,

WITH THE 00Z AND 06Z MODEL RUNS PREDICTING A TROUGH AXIS ALIGNED WITH THE ROCKY

MOUNTAINS AND ABOVE NORMAL 500-HPA HEIGHTS IN THE EAST. YESTERDAYS 12Z AND

TODAY'S 00Z DETERMINISTIC ECMWF RUNS AGREE WITH THE ENSEMBLE MEANS, AS DOES

TODAY'S 12Z GFS DETERMINISTIC RUN, THUS THE ECMWF ENSEMBLE MEAN SOLUTION MOST

HEAVILY WEIGHTED IN TODAY'S BLEND.

THERE IS VERY GOOD AGREEMENT FOR SIGNIFICANTLY BELOW NORMAL TEMPERATURES IN THE

NORTH-CENTRAL CONUS UNDER EXPECTED NORTHERLY UPPER LEVEL FLOW. MOST TOOLS BASED

ON LOW LEVEL TEMPERATURES FROM THE MODELS FAVOR ENHANCED CHANCES FOR

BELOW-NORMAL TEMPERATURES THROUGHOUT MOST OF THE CONUS, EXCEPT FOR THE

SOUTHWEST AND PARTS OF THE FLORIDA PENINSULA. CONFIDENCE IN BELOW-NORMAL MEAN

TEMPERATURES ALONG THE EASTERN SEABOARD IS LOW DUE TO AN EXPECTED WARM START TO

THE PERIOD, AND ALSO THE POSSIBILITY OF THE SOUTHEASTERN RIDGE BEING STRONGER

THAN THE ENSEMBLE MEANS INDICATES. A STRONG SOUTHEASTERN RIDGE WOULD FORCE THE

MID-CONTINENTAL TROUGH TO THE WEST OF THE POSITION PREDICTED BY THE ENSEMBLE

MEANS. THIS POSSIBILITY IS SUGGESTED BY BOTH THE 00Z AND 06Z GFS DETERMINISTIC

RUNS, AND ALSO IS FAVORED BY TELECONNECTIONS BASED ON A POSITIVE 500-HPA

ANOMALY CENTER NEAR 51N, 141W. THIS ALSO LOWERS CONFIDENCE IN THE TEMPERATURE

PREDICTION WEST OF THE ROCKY MOUNTAINS. ABOVE-NORMAL TEMPERATURES ARE FAVORED

FOR MOST OF ALASKA UNDER THE EXPECTED UPPER LEVEL RIDGE.

THE BROAD TROUGH EXPECTED OVER THE CENTRAL CONUS IS EXPECTED TO ELEVATE CHANCES

FOR NEAR TO ABOVE-MEDIAN PRECIPITATION AMOUNTS FOR MUCH OF THE EASTERN PART OF

THE COUNTRY. BELOW-MEDIAN PRECIPITATION IS FAVORED FOR MUCH OF THE SOUTHWESTERN

CONUS AND THE COASTAL PORTIONS OF THE PACIFIC NORTHWEST WHICH ARE EXPECTED TO

BE TO THE WEST OF THE MEAN TROUGH AXIS. MODELS INDICATE ABOVE-MEDIAN

PRECIPITATION FOR THE NORTHERN ROCKIES, ALTHOUGH CONFIDENCE IS NOT HIGH AND

ELEVATED CHANCES ARE RESTRICTED TO A FAIRLY NARROW BAND, REFLECTING SHORT WAVES

MOVING SOUTHWARD IN THE MEAN NORTHWESTERLY FLOW ALOFT. BELOW MEDIAN

PRECIPITATION IS FAVORED FOR EASTERN ALASKA, WITH ABOVE-MEDIAN PRECIPITATION

FAVORED IN THE WEST, REFLECTING THE RIDGE AXIS EXPECTED IN THE CENTRAL PART OF

THE STATE DURING THE PERIOD.

TODAY'S OFFICIAL 500-HPA BLEND CONSISTS OF 10 PERCENT OF TODAY'S 0Z GFS

ENSEMBLE MEAN CENTERED ON DAY 8...20 PERCENT OF TODAY'S 6Z GFS ENSEMBLE MEAN

CENTERED ON DAY 8...40 PERCENT OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON

DAY 8...AND 30 PERCENT OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8.

MODEL OF THE DAY: TODAY'S 00Z ECMWF ENSEMBLE MEAN

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO

GOOD AGREEMENT AMONG THE ENSEMBLE MEAN SOLUTIONS.

8-14 DAY OUTLOOK FOR JAN 07 - 13 2014

THE ENSEMBLE MEAN PREDICTION FOR THE 500-HPA HEIGHT PATTERN FOR THE WEEK-2

PERIOD INDICATES A RETROGRESSION OF THE TROUGH AXIS FORECAST OVER THE CENTRAL

CONUS IN THE 6-10 DAY PERIOD. THIS BRINGS THE TROUGH AXIS MORE IN LINE WITH

TELECONNECTIONS BASED ON THE POSITIVE 500-HPA HEIGHT ANOMALY CENTER PREDICTED

TO PERSIST OVER THE NORTH PACIFIC BETWEEN THE TWO PERIODS. THIS WILL MAKE FOR A

DIFFICULT TEMPERATURE PREDICTION DUE TO THE EXPECTATION OF CHANGING CONDITIONS

DURING THE PERIOD. THE EASTERN PART OF THE COUNTRY EXPECTED TO START THE 8-14

DAY PERIOD ON THE COLD SIDE, AND MODERATE AS THE PERIOD GOES ON. THE WESTERN

PART OF THE CONUS IS EXPECTED TO SEE INCREASING CHANCES OF BELOW-NORMAL

TEMPERATURES LATER IN THE PERIOD. THE HIGHEST CONFIDENCE FOR BELOW-NORMAL

TEMPERATURES REMAINS IN THE NORTHERN GREAT PLAINS OR UPPER MISSISSIPPI VALLEY

WHERE THE CHANCES FAVOR BELOW-NORMAL UPPER LEVEL HEIGHTS THROUGH MOST OF THE

PERIOD. THE FAVORED TEMPERATURE CATEGORY IS PREDICTED TO BE FAIRLY SIMILAR

BETWEEN THE 6-10 AND 8-14 DAY PERIODS, ALTHOUGH CONFIDENCE IS MUCH LOWER IN THE

LATTER PERIOD. ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR THE SOUTHEASTERN CONUS

AS THE MEAN UPPER LEVEL TROUGH RETROGRADES. CONDITIONS IN THE WEST ARE QUITE

UNCERTAIN, WITHOUT A CLEAR CONSENSUS AMONG MODELS ON THE STRENGTH OF THE

RETROGRADING TROUGH. TEMPERATURE CONDITIONS IN ALASKA IN THE 8-14 DAY PERIOD

ARE EXPECTED TO BE SIMILAR TO THE 6-10 DAY PERIOD.

THE 8-14 DAY PRECIPITATION OUTLOOK IS QUITE SIMILAR TO THE 6-10 DAY PERIOD. THE

STORM TRACK IS EXPECTED TO BE DISPLACED NORTHWARD ALONG THE PACIFIC COAST DUE

TO THE EXPECTED NORTH PACIFIC RIDGE, LEADING TO BELOW-MEDIAN PRECIPITATION

AMOUNTS BEING FAVORED FOR MUCH OF THE WEST. THE CHANCES FOR ABOVE-MEDIAN

PRECIPITATION ARE ENHANCED THROUGHOUT MUCH OF THE EASTERN HALF OF THE NATION

WITH ENHANCED SOUTHWESTERLY FLOW EXPECTED AHEAD OF THE MEAN TROUGH PROVIDING A

SOURCE OF MOISTURE FROM THE GULF OF MEXICO FOR ANY SHORT WAVES EMBEDDED IN THE

FLOW. THE 8-14 DAY PRECIPITATION FOR ALASKA IS QUITE ALSO QUITE SIMILAR TO THE

6-10 DAY PERIOD WITH THE MEAN RIDGE EXPECTED TO REMAIN NEARLY STATIONARY

BETWEEN THE TWO PERIODS.

THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 10 PERCENT OF TODAY'S 0Z GFS

ENSEMBLE MEAN CENTERED ON DAY 11...20 PERCENT OF TODAY'S 6Z GFS ENSEMBLE MEAN

CENTERED ON DAY 11...40 PERCENT OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED

ON DAY 11...AND 30 PERCENT OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY

11.

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: ABOUT AVERAGE, 3 OUT OF 5, DUE

TO FAIRLY GOOD AGREEMENT AMONG THE ENSEMBLE MEANS OFFSET BY UNCERTAINTY

ASSOCIATED WITH THE ANTICIPATED RETROGRESSIVE CIRCULATION PATTERN OVER THE

CONUS.

[1234snow]

I'm going to have to side with the Euro on this one. It has been consistent with the trough in the east while the GFS has been all over the place. I do think that the Euro is likely overdone as it seemed to do this here recently but it is on the right track. I would doubt the polar vortex makes it that far south though but it would be epic if it made it into the U.S.