Central/Western Summer Medium/Long Range Discussions

[wildweatherman179]

Mighty impressive pattern via the EURO Ensemble 500mb and after seeing the various operational and other Global ensembles in the medium/longer range, it certainly raises an eyebrow and memories of 83 and 89 when a somewhat similar pattern developed catching many off gaurd as they headed away for the long Christmas Holiday period to return to siginicant damage from bursting pipes and property damage from prolonged sub freezing temperatures.

Wow, that's beautiful. Lol. So are we potentially talking about making history by the time winter is over here in the plains and in the northwest and mtn west?

[Srain]

The longer range GEFS anomalies continue to advertise a mighty chilly pattern just prior to the Holiday period.

[Srain]

It will be interesting to see if these very cold anomalies continue the trends we have seen the past several cycles.

[wildweatherman179]

Yeah. The little kid inside me is bouncing off the walls right now. Its going to be could but awesome.

[1900hurricane]

From FWD:

 

 

Could be we looking at another shot of arctic air across North Texas? Many of the long-range forecast models are hinting at this, so this graphic depicts the possibilities. Two upper level low pressure systems may be responsible for sending arctic air our way in the 8-14 day portion of the forecast. The first, labeled L1, is currently over Alaska. This upper low is expected to move away from Alaska and send cold air our way December 20th or 21st. It will send some of the cold Alaska and northern Canada air south into the plains. How cold we'll get and how long it will last will depend at least partially on how far south it moves. If it takes a southerly track, we can expect at least a few days of temperatures well below normal late next week. The secondary upper low, labeled L2, is what may bring a reinforcing shot of arctic air into the United States. If this secondary upper low moves south, over the western United States, it will likely send some very cold Siberian air into the central U.S., but this would not happen until just before Christmas, if it happens at all. While models indicate we'll get colder late next week, there is not very good agreement on the track and strength of the cold air associated with L2. If L2 takes the southern track depicted with the white 2. in the image, it will send a reinforcing shot of very cold air south on December 22nd or 23. If it just circles around the Arctic Circle, as depicted by the white 1. in the image, it will have very little to no impact on temperatures across North Texas. We'll be watching these systems closely over the next several days. Keep in mind a LOT can change between now and then, 8-14 day forecasts typically change dramatically before models come to a consensus solutions.

[wildweatherman179]

Well, I'm not trying to wishcast it or anything like that but if the pattern tells us anything, there's a very good chance that its going to be a subzero Christmas. :-)

[andyhb]

00z Euro got my attention for a potential severe weather setup in the Ozarks/Lower MS Valley and adjacent areas around a week from now.

[Srain]

We may need to drop that severe weather potential a bit further S into Texas as Lee side cyclogensis develops and a bit of a negative tilted trough develops across Central Texas on Saturday.

[ouamber]

Where do you guys see this Low tracking? Arklatex? or Further South? or north into SE OK?

[wildweatherman179]

Where do you guys see this Low tracking? Arklatex? or Further South? or north into SE OK?

I'm thinking Arklatex personally but I'm trying to figure out whether it turns more NE at that point and shears out or continues more easterly for a bit before maturing, shearing and heading up the east coast.

[wildweatherman179]

I think with it we are ultimately wondering where the snowfall track will be. I'm thinking it will bear strong resemblance to our last storm. :-)

[oldlogin]

00z Euro got my attention for a potential severe weather setup in the Ozarks/Lower MS Valley and adjacent areas around a week from now.

Spot on Andy

[Superstorm93]

Might need a thread for this event in the coming days...

 

Looks to be a decent producer. 

[wildweatherman179]

Well, its not snow but its definitely interesting.

[Srain]

There is not a lot to hang ones hat on in the medium range since there remains a lot of volatility beyond the day 4 period. It does appear the northern stream will remain active with moisture starved clipper systems crossing Canada and a stronger front arrives this weekend across the Inter Mountain West into the Plains. The recent telecommunication trends are not hopeful as the AO is only forecast to approach neutral to slightly negative and the PNA is also neutral to slightly positive around the New Year time frame. The EPO does appear to try to trend negative as well as the WPO, but with the daily lack of continuity via the Global  deterministic and ensembles a conservative approach seems best for the medium range and beyond. The West looks to remain warm and dry and the Southern Plains may see a storm system near the 3rd of January, +/- a day or two. There is still a lot of uncertainty regarding the 500mb low and if it will shear out in the Southern stream leading to a low confidence forecast at best.

[Srain]

The forecast from New Years Day into mid January is trending to that of what we saw in late November/early December where a –WPO (Western Pacific Oscillation)/-EPO (Eastern Pacific Oscillation) regime where heights were high across the North Pacific/Gulf of Alaska due to the unusually warm waters across the Northern Pacific ushered in much colder air into the Western 2/3rds of North America and brought much below normal temperatures with a stormy pattern as strong/potent upper lows and a noisy sub tropical jet brought bouts of wintry weather across our Region. The PNA (Pacific- North American Oscillation) is forecast to relax back to a more neutral or slightly negative state which is what happen when we were very chilly early in the month of December where a persistent trough developed across the Great Basin/Inter Mountain West and into the Plains while the East Coast saw a stout Ridge and kept that area warm with above normal temperatures. The fly in the ointment is the AO (Arctic Oscillation) which is currently forecast to drop into negative territory which tends to have major effects of the location of the Polar Vortex near Hudson Bay. The Global ensembles have been hinting that the PV will shift back W and S, or to the West of Hudson Bay. Currently our source regions of Eastern Alaska/NW Territories of Western Canada are witnessing temperatures of -50 F or about 10-20 F colder than what we saw early in December.

 

There are indications that the tropical Pacific may become a bit more active with convection and that tends to throw a wild card into the forecasting schemes when looking at the medium/long range forecast, but after a relaxation of the pattern in our part of the world, signals are growing that another pattern change may be developing that could have major impacts on the sensible weather we can expect in the early to mid January time frame.

[wildweatherman179]

Can you say awesome. Lol. I'm excited.

[Minnesota Meso]

The forecast from New Years Day into mid January is trending to that of what we saw in late November/early December where a –WPO (Western Pacific Oscillation)/-EPO (Eastern Pacific Oscillation) regime where heights were high across the North Pacific/Gulf of Alaska due to the unusually warm waters across the Northern Pacific ushered in much colder air into the Western 2/3rds of North America and brought much below normal temperatures with a stormy pattern as strong/potent upper lows and a noisy sub tropical jet brought bouts of wintry weather across our Region. The PNA (Pacific- North American Oscillation) is forecast to relax back to a more neutral or slightly negative state which is what happen when we were very chilly early in the month of December where a persistent trough developed across the Great Basin/Inter Mountain West and into the Plains while the East Coast saw a stout Ridge and kept that area warm with above normal temperatures. The fly in the ointment is the AO (Arctic Oscillation) which is currently forecast to drop into negative territory which tends to have major effects of the location of the Polar Vortex near Hudson Bay. The Global ensembles have been hinting that the PV will shift back W and S, or to the West of Hudson Bay. Currently our source regions of Eastern Alaska/NW Territories of Western Canada are witnessing temperatures of -50 F or about 10-20 F colder than what we saw early in December.

 

There are indications that the tropical Pacific may become a bit more active with convection and that tends to throw a wild card into the forecasting schemes when looking at the medium/long range forecast, but after a relaxation of the pattern in our part of the world, signals are growing that another pattern change may be developing that could have major impacts on the sensible weather we can expect in the early to mid January time frame.

 

Srain:  I would hope that you could keep posting the teleconnection indices, since Alan's site has gone to pay per view, well lets just say I miss them greatly... 

[OKpowdah]

Anyone notice the 1068mb+ high, with -40F 2m temps working south over the Rockies at hr300 on the 00z GFS pic.twitter.com/6yTD0BQyig

[Srain]

There is growing credence that a flip to a much colder pattern is ahead in the medium range. The WPO/EPO continue to drop into negative values and the AO appears to flirt with slightly neutral to near the -2 range suggesting a blocking pattern may develop and the Day 6 Euro ensemble mean as well as the various other deterministic and ensemble guidance are latching onto a solution that much cold air will spill S into the Inter Mountain West and Plains. What remains uncertain are any embedded short wave disturbances dropping S along the Western flank of the trough before crossing Northern Mexico and turning NE.

[wildweatherman179]

That's beautiful. :-) Here's to hoping...

[baroclinic_instability]

12z ECMWF continues to prog a 1985 style vortex over the Lakes. Incredible if that verified.

[Srain]

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.
 

[wildweatherman179]

In English that means brrrrrrrrr.....brrrrrrrr and more brrrrrrrrr. Lol. Its gonna be cold. Possibly snowy from eastern Oklahoma to the northeast.

[Srain]

Once again attention turns to the medium/long range across our Region. After the Arctic chill transitions to a moderating split zonal flow, a parade of Pacific storms track beneath the GOA Ridge and develop an increasingly deep Western trough. Cool and unsettled weather returns to the West Coast where increasing Pacific moisture returns to WA/OR and Northern CA. As the week progresses and the Arctic high pushes E, a return flow off the Western Gulf appears to set the stage for increasing moisture and perhaps some heavy rainfall across TX into LA by next weekend. The GFS/GEFS solutions offer a progressive Southern stream flow of a series of fast moving 5H troughs while the deterministiic Euro as well as its ensemble mean suggest more of a cut off solution with a much deeper trough extending into Southern California and Northern Mexico. The Euro solution has some credence with the synoptic pattern as well as telecommunication indices suggested by the 00Z of guidance. It will be interesting to see if the slow moving Western/Central trough does indeed phase with the Polar jet allowing a robust cold core closed 5H low to meander E across Northern Mexico into Texas near January10/11 time frame. If the Euro were to verify, a stormy period may develop across the Southern Rockies and the Southern Plains with strong storms possible along the Western Gulf Coast next weekend.

[wildweatherman179]

What you thinking as far as the wintry side of things on that system on the 10th/11th? I'm hoping for some decent snow for eastern OK and northern Arkansas but many say not likely. What you think?

[donsutherland1]

Correction...

 

Fayetteville's 2.0" snowfall was the third biggest snowfall on 1/6 as per the Drake Field record, which goes back to 1949. The biggest was 4.0" on January 5, 1970. This data only concerns 1/5. Fayetteville has had larger snowfalls.

 

I regret the earlier error.

[Srain]

The Climate Prediction Center has updated their Day 8-14 Outlook...looks like some colder air may return across our Region to end the month of January.

8-14 DAY OUTLOOK FOR JAN 22 - 28 2014 
 
TODAY'S WEEK-2 OUTLOOK REFLECTS THE GROWING POSSIBILITY OF ONE OR MORE 
SUBSTANTIAL COLD AIR OUTBREAKS ACROSS THE CONUS HEADING TOWARD THE END OF THE 
MONTH. THE 500-HPA HEIGHT MANUAL BLEND REVEALS A HIGHLY AMPLIFIED PATTERN WITH 
A MEAN RIDGE FORECAST JUST OFF THE WEST COAST EXTENDING NORTHWARD INTO EASTERN 
ALASKA. DOWNSTREAM, A DEEP TROUGH IS FORECAST ACROSS THE EASTERN CONUS. THE 
EVOLUTION OF THE FORECAST HEIGHT PATTERN OVER THE PAST FEW DAYS SUGGESTS THAT 
THE SOURCE REGION FOR POST-FRONTAL AIR MASSES WILL BE GROWING COLDER AS 
CROSS-POLAR FLOW BECOMES BETTER ESTABLISHED. TEMPERATURE PROBABILITIES MAY BE 
TOO CONSERVATIVE AND GREATER PROBABILITIES FOR BELOW-NORMAL ARE LIKELY GOING TO 
EXPAND OVER THE NEXT COUPLE OF FORECAST CYCLES. LATE IN THE PERIOD, COLDER AIR 
MASSES ARE MORE LIKELY TO IMPACT PARTS OF THE NORTHERN ROCKIES AS WELL, WHERE 
PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES HAVE BEEN DRASTICALLY REDUCED FROM 
YESTERDAY'S OUTLOOK.
 
TELECONNECTIONS UPON THE MAJOR HEIGHT ANOMALY CENTERS (WEST COAST, EASTERN 
CONUS, NORTH ATLANTIC) SUGGEST THE FORECAST WAVE PATTERN MAY CONTAIN 
WAVELENGTHS THAT ARE TOO LARGE GIVEN THE POTENTIAL AMPLITUDE OF THE PATTERN. 
THIS INCREASES UNCERTAINTY, ESPECIALLY IN THE PRECIPITATION FORECAST, WHERE 
SHORTWAVE AMPLIFICATION SEEMS LIKELY DURING THE WEEK-2 PERIOD, THOUGH IT'S 
UNCERTAIN WHEN IT WILL OCCUR. CONFIDENCE IS FAIRLY HIGH THAT ANY AMPLIFICATION 
WOULD OCCUR IN THE EASTERN HALF OF THE CONUS; NEAR-MEDIAN PRECIPITATION IS 
FAVORED ALONG THE EAST COAST AS A RESULT. ABOVE-MEDIAN PRECIPITATION IS FAVORED 
FROM THE CLIMATOLOGICALLY-DRY NORTHERN PLAINS, WHERE MULTIPLE SHORTWAVES 
ENTERING THE MEAN TROUGH ARE LIKELY TO CAUSE SOME SNOWFALL, TO NEW ENGLAND, 
WHERE ANY STORM TRACKS ARE FAVORED TO CONVERGE.
 
THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 15 PERCENT OF TODAY'S 
OPERATIONAL 0Z GFS CENTERED ON DAY 11...15 PERCENT OF TODAY'S OPERATIONAL 6Z 
GFS CENTERED ON DAY 11...15 PERCENT OF TODAY'S 0Z GFS ENSEMBLE MEAN CENTERED ON 
DAY 11...15 PERCENT OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 11...AND 40 
PERCENT OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11.
 
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: ABOVE AVERAGE, 4 OUT OF 5, DUE 
TO GOOD AGREEMENT AMONG MODELS AND FORECAST TOOLS, OFFSET SLIGHTLY BY 
UNCERTAINTY IN THE TEMPERATURE OUTLOOK ACROSS THE CENTRAL CONUS.

[wildweatherman179]

I hope I can get a little snow out of all that cold. Not going to get my hopes up though.

[Srain]

The GFS suggests a stout EPO Ridge and cross polar flow developing before truncation. The trends continue to advertise a shot of ‘colder’ Siberian air settling on our side the world. We will see.