Central/Western Summer Medium/Long Range Discussions

[Srain]

B_I believe the time has come for a medium/long range general discussion thread for our region. We have many very knowledgeable Red Tags and enthusiasts across our vast geographical region and the time has come to tap into that vast wealth of knowledge instead of fragmented discussions that have been the theme of the past. Obs can continue to go into the various regional discussion areas, but an overall pattern discussion would help draw attention to our region for those that our not familiar with our climo and also provide a place for the East Coast folks to look for what may be upstream in their specific regions.

[Srain]

What I see in the longer range are fairly good indicators that a -AO/-NOA regime with a relaxing EPO lending to a +PNA as the N Pacific calms down in about a week to 10 days. Add to that a SSW (Sudden Stratospheric Warming) event that is underway already with the Polar Vortex in Eurasia leading to a PV split that should drop into Canada near the 5th to 7th of December. There is a lot of snow building across Western Canada and indications are the Rockies and Plains will begin to get some snow cover after the first week of December.

[Portastorm]

^{I've been hoping for a thread like this for a long time. Thanks srain! I'm curious if there is a possibility of Typhoon Bopha influencing the northern jet, and accordingly, influencing the pattern downstream over the CONUS.}

[Quixotic1]

Awesome, Srain.

After the brutal summer last year, the uneventful winter and the limited storm events this past spring, I'm nervous going into this winter.

The recent blocking is encouraging as is the rapid snow cover buildup in October. I'll be more confident when the EPO cooperates.

[baroclinic_instability]

I am ready for this garbage to end. These two plots basically tell the existence of my time in AK this fall and early winter. We are at 1/4th the climatological average with nearly daily offshore northerly flow.

As for this thread, I am glad to get it going. We have a lot of new red tags in this region with serious medium/long range weather skills, but we never had a serious discussion thread.

[Srain]

A bit of promising news via the 12Z Euro. It does appear that some of the cold building across Western Canada will head S and begin to spill into the Plains. Perhaps a bit of a +PNA developing as well...

[JSchwake28]

Agreed Srain. It appears the massive Aleutian ridge will begin to break down/reposition itself more over Asia.This allows for some ridging to develop across the eastern Pac and the cold air currently in western Canada (saw some -40s this morning in the Yukon territory) to plunge southward into the plains.

Looking at the D10 euro ensembles we see this very well, although at first glance the Pacific looks awfully similar to most of last winter. (I'm really just beginning to dabble in longer range forecasting so please correct me if I'm entirely wrong) Here's a graphic depiction of what I'm talking about.

However, with the -AO looking pretty likely and a -NAO over the Atlantic, one would think that we would see a different resut from last year and cold air would actually be able to dive southward into the states.

Here's to hoping this comes to fruition! After last year's debacle I'm still waiting to experience some real arctic air out here in the plains.

[Srain]

The overnight operational European and 06Z GEFS continue to advertise a fairly significant change in the patter as we move toward the 10th of December -/+ a couple of days. The Plains are looking to benefit from that very chilly air that has been building across Western Canada and it is encouraging to see a +PNA developing.

[OKpowdah]

Re: Typhoon Bopha,

It's not quite a classic W Pac recurvature to downstream pattern change event, but you can still see the effects quite well.

Notice as Bopha moves over the Philippines, the W Pac jet gains latitude and intensifies, with a long fetch of southerly 250mb irrotational wind radiating from the typhoon toward the entrance region of the jet.

In this instance, I think Bopha definitely contributes to the retrogression of the Aleutian block toward Kamchatka by the end of the first week of December ... evolving into a rex block over E Asia.

This allows for some flat ridging to develop over the E Pac, in RNA form, during the second week of December ... a signal that has become more popular in the long range guidance in the last few days. The developing pattern looks more and more favorable for a trough east of the Rockies.

[OKpowdah]

Another way of viewing this, with theta on the DT. Can see ridging getting pumped up over over the W Pac toward Kamchatka along with the intensification of the jet

[baroclinic_instability]

Agreed Srain. It appears the massive Aleutian ridge will begin to break down/reposition itself more over Asia.This allows for some ridging to develop across the eastern Pac and the cold air currently in western Canada (saw some -40s this morning in the Yukon territory) to plunge southward into the plains.

Looking at the D10 euro ensembles we see this very well, although at first glance the Pacific looks awfully similar to most of last winter. (I'm really just beginning to dabble in longer range forecasting so please correct me if I'm entirely wrong) Here's a graphic depiction of what I'm talking about.

However, with the -AO looking pretty likely and a -NAO over the Atlantic, one would think that we would see a different resut from last year and cold air would actually be able to dive southward into the states.

Here's to hoping this comes to fruition! After last year's debacle I'm still waiting to experience some real arctic air out here in the plains.

The overnight operational European and 06Z GEFS continue to advertise a fairly significant change in the patter as we move toward the 10th of December -/+ a couple of days. The Plains are looking to benefit from that very chilly air that has been building across Western Canada and it is encouraging to see a +PNA developing.

Another way of viewing this, with theta on the DT. Can see ridging getting pumped up over over the W Pac toward Kamchatka along with the intensification of the jet

Nice posts guys. It does seem this pattern shift constitutes a huge shift from the previous month+, and something we saw little of last winter (should it verify). A trough out west, cold air piling up in Canada...it almost seems foreign. I am getting excited for something different. Oh, and I will be in MN from the 16th-27th of Dec. We will have to see how the Pac jet eventually evolves...but these patterns can pay dividends for the N Plains and N Intermountain W.

[mnweather]

Nice posts guys. It does seem this pattern shift constitutes a huge shift from the previous month+, and something we saw little of last winter (should it verify). A trough out west, cold air piling up in Canada...it almost seems foreign. I am getting excited for something different. Oh, and I will be in MN from the 16th-27th of Dec. We will have to see how the Pac jet eventually evolves...but these patterns can pay dividends for the N Plains and N Intermountain W.

Hopefully you bring us some luck.

[andyhb]

Could use something to augment the tornado totals for this year, considering they are struggling to hit 1,000 (and might not even with a more significant event before the end of the year).

[Portastorm]

Just a shout out of "thanks" to wxwatcher91 for responding to my question about Bopha. Much appreciated! I learn something every day on this forum.

[JSchwake28]

The trend for a +PNA to develop by day 10 continues. Here's the latest GFS and Euro ensembles for D10.

As to be expected 240 hours out, there are a number of differences but there seems to be a growing consesus towards a ridge developing into the Gulf of Alaska by around 12/8. This should allow at least a brief shot of some arctic air diving into the northern Rockies and plains and possibly into the east my mid month. The question is, will it be a transient pattern or do we see an end to the Aleutian ridge? The GFS ensembles continue to keep a ridge in the eastern Pac through the period, but that's just one run with little consistency as of late.

I'm not that familiar with stratospheric warming events but it appears there is currently a warming in the stratosphere around 70mb working it's way upwards. I'm very curious as to what, if any, effects this could have on blocking as we head into late December. Regardless, it appears that the current Pacific pattern is going to be breaking down and the current warmth across much of the country should relax towards mid month.

[Srain]

A bit different view of the 12Z Operational GFS North Pacific 500mb chart suggest a stout +PNA developing offshore of the West Coast pumping a ridge N into the Aleutian Islands/near or just E of the Bering Sea. A deep trough begins to develop into the Intermountain West suggesting that very cold air that has been bottled up in Western Canada will become dislodged and head S into the Plains. Also of note is a raging Polar jet with embedded short wave energy digging into the Great Basin.

Switching back to the North American 850mb view, one can see the cold air spilling S and a Pacific Tropical connection develop providing over running moisture over a chilly surface air mass. The trends continue to suggest that after we get beyond next weekend, we may change to a much colder pattern and I would not be surprised to see a fairly significant Winter Storm develop across the Plains providing for less air mass modification and just perhaps laying some snow cover down. We will see.

[BlizzardWx]

The last three runs of the ECMWF seem to imply a pending arctic blast for the western states whereas the GFS has predominantly tried to send things more east. I don't do well here unless the trough digs offshore at least a bit and picks up moisture. Not sure if that is in the cards this go around.

[Srain]

It does appear we are finally heading toward that change in pattern now depicted in the medium range operational and ensemble guidance. Heights build across the NE Pacific and a trough develops into the Intermountain West and Plains. That should usher in some very chilly air that has dominated the Yukon Territory over that past month or so. I noticed Dawson has temps running near the -40 Celsius range for low and -teens/-20's C for high temps. Some of that Arctic air will dive S and setup shop across the Northern tier of the Rockies and Plains late this coming week. Looking a bit further out, there are indications a +PNA regime will continue into the mid December time frame. The HPC is also mentioning the pattern change as well:

PRELIMINARY EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD

901 AM EST SUN DEC 02 2012

VALID 12Z THU DEC 06 2012 - 12Z SUN DEC 09 2012

...SYNOPSIS...

THE WESTERN U.S. STORM RELAXES DURING THE MEDIUM RANGE PERIOD. IN

THE EASTERN U.S...A SLOW MOVING FRONT WILL BRING A CHANCE OF RAIN

AND POSSIBLY A ZONE OF WINTRY MIX BY NEXT WEEKEND.

THE MEDIUM RANGE FORECAST FEATURES A GRADUAL CHANGE IN THE LARGE

SCALE PATTERN. A LONG-LIVED REX BLOCK AND SPLIT FLOW REGIME

NEAR/SOUTH OF THE ALEUTIAN ISLANDS WILL BREAK DOWN. THIS ALLOWS

MORE COLD AIR TO SPILL OFF OF CONTINENTAL ASIA AND DEEPEN A

LONGWAVE TROUGH OVER THE CENTRAL PACIFIC. THIS PROPS UP A RIDGE

OVER THE EASTERN PACIFIC...BRINGING AN END TO THE PROLONGED HEAVY

RAIN EVENT ALONG THE WEST COAST OF THE U.S. DOWNSTREAM...MODELS

AND TELECONNECTIONS PREDICT DEVELOPMENT OF A BROAD SCALE

POSITIVELY TILTED TROUGH...SUPPORTED BY INTRUSIONS OF ARCTIC AND

MODIFIED ARCTIC ARE INTO THE CENTRAL/EASTERN STATES.

[Srain]

EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD

223 PM EST MON DEC 03 2012

VALID 12Z THU DEC 06 2012 - 12Z MON DEC 10 2012

GENERAL FLOW PATTERN

==============================

RELATIVELY FLAT FLOW ACROSS THE CONUS AT THE BEGINNING OF THE

FORECAST PERIOD WILL BEGIN TO AMPLIFY AS RIDGING BUILDS IN OVER

THE EASTERN PACIFIC AND BROAD UPPER TROUGHING DIGS THROUGH THE

WESTERN U.S. THIS WEEKEND. THE UPPER TROUGH SHOULD WORK ITS WAY

INTO THE CENTRAL U.S. ON MONDAY...AND A STRONG COLD FRONT WILL

BEGIN TO PUSH EASTWARD THROUGH THE PLAINS/MISSISSIPPI VALLEY.

ENSEMBLE MEANS APPEAR TO HAVE A GOOD HANDLE ON THE EVOLUTION OF

THE LARGE SCALE FLOW DURING THE MEDIUM RANGE PERIOD...BUT A DECENT

AMOUNT OF SPREAD AMONG INDIVIDUAL ENSEMBLE MEMBERS AS WELL AS

DETERMINISTIC GUIDANCE INDICATES THAT THERE IS STILL SOME

UNCERTAINTY IN THE FORECAST...ESPECIALLY BY DAY 6 AND 7. THESE

DIFFERENCES IN THE MODELS LEAD TO FAIRLY SIGNIFICANT DIFFERENCES

IN THE SENSIBLE WEATHER ACROSS THE STATES.

MODEL DIFFERENCES

==============================

THE MOST NOTABLE DIFFERENCE WITH MEDIUM RANGE GUIDANCE IS WITH

JUST HOW FAST OR SLOW THE UPPER TROUGH DIGGING THROUGH THE WEST

THIS WEEKEND WILL PROGRESS INTO THE CENTRAL U.S. ON MONDAY...AND

THEN HOW FAST A COLD FRONT WILL EJECT EASTWARD OUT OF THE ROCKIES

AND ACROSS THE PLAINS/MISSISSIPPI VALLEY. EACH PIECE OF GUIDANCE

HAS BEEN STRUGGLING WITH ITS OWN RUN TO RUN CONTINUITY ISSUES LATE

IN THE FORECAST PERIOD. RECENT RUNS OF THE GFS HAVE BEEN

ADVERTISING ONE OF THE SLOWEST SOLUTIONS...HOLDING A BULK OF THE

ENERGY BACK OVER THE SOUTHWESTERN U.S. THROUGH MONDAY MORNING. ON

THE FLIP SIDE...THE PAST FEW RUNS OF THE ECMWF HAVE BEEN MUCH

FASTER WITH PROGRESSING THE ENERGY EASTWARD INTO THE CENTRAL

U.S....AND WITH PUSHING THE ASSOCIATED COLD FRONT EASTWARD. BY

MONDAY MORNING...THE 12Z GFS AND 12Z ECMWF ARE OVER 400 MILES

APART WITH THE LOCATION OF THE COLD FRONT THROUGH THE SOUTHERN

U.S.. THE GFS KEEPS THE FRONT BACK IN THE MIDDLE MISSISSIPPI

VALLEY/SOUTHERN PLAINS...WHILE THE ECMWF RACES THE BOUNDARY OUT TO

THE SOUTHERN APPALACHIANS AND FLORIDA PANHANDLE. ALSO...THE 00Z

ECMWF IS ONE OF THE QUICKEST TO SPIN UP A SURFACE LOW...TRACKING A

PRETTY DEEP CYCLONE OVER THE UPPER GREAT LAKES BY MONDAY MORNING.

FORTUNATELY...THE ENSEMBLE MEANS ARE IN SOMEWHAT OF AGREEMENT

WITH THE TIMING ALOFT...WITH THE 00Z GEFS MEAN BEING ONLY SLIGHTLY

SLOWER THAN THE 00Z ECMWF ENSEMBLE MEAN. HOWEVER...EVEN THE MEANS

STILL SHOW SOME UNCERTAINTY WITH THE EXACT TIMING OF THE COLD

FRONT.

PREFERENCES

==============================

THE MEDIUM RANGE FORECAST STARTED WITH A BLEND OF THE 00Z

GFS/ECMWF SINCE THERE WAS DECENT AGREEMENT AMONG DETERMINISTIC

GUIDANCE. AFTER DAY 4...AN INCREASING AMOUNT OF SPREAD WITH

ENSEMBLE MEMBERS...ESPECIALLY WITH THE UPPER TROUGH PROGRESSING

INTO THE CENTRAL U.S. ON MONDAY...LED TO A TRANSITION TOWARDS THE

00Z GEFS/ECMWF ENSEMBLE MEANS. THE MORNING BLENDS RESULTED IN

MINIMAL CHANGES TO CONTINUITY...AND NO CHANGES WERE MADE FOR THE

FINAL ISSUANCE SINCE THE AVAILABLE 12Z GUIDANCE DID NOT OFFER ANY

BOOST IN CONFIDENCE FOR A PARTICULAR SOLUTION.

SENSIBLE WEATHER

==============================

CONDITIONS WILL GRADUALLY COOL OVER THE NORTHWESTERN U.S. AS THE

UPPER TROUGH DIGS IN OVER THE REGION THIS UPCOMING WEEKEND. ONCE

THE ASSOCIATED COLD FRONT EJECTS OUT OF THE ROCKIES ON

MONDAY...TEMPERATURES SHOULD DROP PRETTY QUICKLY BEHIND THE

BOUNDARY AS IT PUSHES THROUGH THE PLAINS/MISSISSIPPI VALLEY. IN

TERMS OF PRECIPITATION ACROSS THE NATION...A FRONTAL BOUNDARY

SETTING UP THROUGH THE OHIO/MIDDLE MISSISSIPPI VALLEY WILL LIKELY

BE THE FOCUS FOR A WELL ORGANIZED BAND OF MODERATE RAINS THIS

WEEKEND.

GERHARDT

[JSchwake28]

Well now that the pattern change over the next 1-2 weeks has become apparent, it's time to look forward to any possible events. It appears likely that a storm will form somewhere in the southern plains and ride northeastward along the arctic front into the Great Lakes region early next week. There are differences in the evolution of the system, as the GFS seems to want to hold back some energy in the SW while the Euro is a bit more progressive, but the eventual outcomes are fairly similar in developing a low along the front. It's obviously way to early for any specifics but I would think it is pretty likely that some accumulating snows fall somewhere in the midwest in the Monday-Tuesday timerame. Any accumulating snows, especially across the northern plains, will only enhance cold temperatures moving in behind the system.

As for the remainder of the month, it appears likely that cooler than normal temperatures along with several chances for snow will occur across the northern plains. As long as the AO continues to be forecast < 0 along with an eastern Pac ridge, chilly conditions should persist from the northern Rockies into the midwest.

[prinsburg_wx]

Well now that the pattern change over the next 1-2 weeks has become apparent, it's time to look forward to any possible events. It appears likely that a storm will form somewhere in the southern plains and ride northeastward along the arctic front into the Great Lakes region early next week. There are differences in the evolution of the system, as the GFS seems to want to hold back some energy in the SW while the Euro is a bit more progressive, but the eventual outcomes are fairly similar in developing a low along the front. It's obviously way to early for any specifics but I would think it is pretty likely that some accumulating snows fall somewhere in the midwest in the Monday-Tuesday timerame. Any accumulating snows, especially across the northern plains, will only enhance cold temperatures moving in behind the system.

As for the remainder of the month, it appears likely that cooler than normal temperatures along with several chances for snow will occur across the northern plains. As long as the AO continues to be forecast < 0 along with an eastern Pac ridge, chilly conditions should persist from the northern Rockies into the midwest.

Models showing the 1st real shot of accumulating snow of the season for a good portion of sd & c/s minnesota late friday into sat.

[JSchwake28]

Models showing the 1st real shot of accumulating snow of the season for a good portion of sd & c/s minnesota late friday into sat.

That system definitely looks to lay down some snowcover throughout much of sd and minnesota. Maybe a 1-2 punch for some of those areas? Either way, looks like an interesting pattern shaping up over the next few weeks .

Hopefully the stage is set for a white christmas across much of the region. I can't imagine seeing another brown christmas up here in the forks.

[prinsburg_wx]

That system definitely looks to lay down some snowcover throughout much of sd and minnesota. Maybe a 1-2 punch for some of those areas? Either way, looks like an interesting pattern shaping up over the next few weeks .

Hopefully the stage is set for a white christmas across much of the region. I can't imagine seeing another brown christmas up here in the forks.

I hope so, last year i had a muddy 1" on the ground at xmas.

I hope the upcoming pattern pans out to more wintry weather and the whole region can enjoy a white christmas.

[Srain]

PRELIMINARY EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD

827 AM EST TUE DEC 04 2012

VALID 12Z SAT DEC 08 2012 - 12Z TUE DEC 11 2012

PRELIMINARY UPDATE...

RELIED ON THE 00Z/04 ECENS MEAN TO UPDATE THE PRELIMINARY FRONTS

AND PRESSURES FOR DAYS 3 THROUGH 7. THE DETERMINISTIC MODELS

DIVERGE SHARPLY BY DAY 5, WITH EMPHASIS ON DIFFERENT SHORTWAVES

ALONG THE POLAR FRONT FROM THE CENTRAL UNITED STATES INTO EASTERN

CANADA. THE GUIDANCE DOES AGREE ON THE OVERALL FLOW, WITH A

NEGATIVE PNA PATTERN FOR THE FORESEEABLE FUTURE. THE 00Z/04 GEFS

MEAN IS WELL CORRELATED WITH THE ECENS MEAN FROM THE SAME RUN, BUT

HINTS AT MORE SPLIT IN THE FLOW NEAR THE OHIO VALLEY AND GREAT

LAKES BY DAY 7. THE ECENS MEAN HAS BEEN STEADY FOR FOUR MODEL

CYCLES NOW, AND HAS PROVEN TO BE A USEFUL GUIDE WHEN THE

DETERMINISTIC MODELS ARE ALL OVER THE PLACE. THE MEAN TROUGH FROM

THE WEST INTO THE PLAINS WILL SET THE STAGE THE FIRST CHANCE OF

WIDESPREAD ICE AND SNOW THIS SEASON IN THE LOWLANDS OF THE CORN

BELT AND THE WESTERN GREAT LAKES.

[InstantWeatherMaps]

Sorry I've been away from the forum for a while... I released my winter forecast a week ago: http://www.instantweathermaps.com/wf_2012-2013.php

[Srain]

The over night operational and ensemble guidance has trended slightly more progressive and a bit further N in regards to the 500mb upper low/trough suggesting a quicker moving cold front and a bit less in the way of moisture. The 00Z UKMet does hold a closed low back in Arizona/New Mexico a bit longer and suggests a bit more southern track across Texas. All in all the long awaited pattern change that we have been discussing is looking likely as heights rise across the NE Pacific and the never ending Gulf of Alaska Low Pressure vortex breaks down. That tends to favor a general troughiness across the Intermountain West and Plains. That type of pattern does bode well for cooler temps and general storminess across the Southern Plains and the Western Gulf Coast as weak waves of low pressure develop along the Coast from time to time.

[JSchwake28]

Looks like the fun should begin within the next couple of days. The latest models continue to show the eastern Pac ridge developing by this weekend with the mean trough developing over the central US lasting through at least the next 10-15 days. As long as the eastern Pac ridge stays put, especially combined with a -AO/-NAO, cold air should continue to make intrusions into the north central US. Models show, and the pattern looks to support clipper after clipper driving through the northern plains, with arctic highs dropping southward in their wake. In fact, there looks to be 2 systems that will bring accumulating snow to areas of the Dakotas and MN by the end of the weekend. Also, with the mean trough centered over the central US, I wouldn't be surprised to see an impressive system or two develop across the lower Mississippi valley and push up into the Great Lakes as well.

Looks like the first shot of fairly widespread below zero readings up around here may come overnight Sunday. Thereafter it looks likely that we'll see a new cold shot every few days. Any areas that are able to lay down a snowpack could possibly see temperatures rivaling last years coldest day (which obviously isn't all that impressive) before Christmas arrives. Granted it's a week out and I'm sure the models will moderate some in time, but glancing at tonight's 0z models shows some impressive cold air working into the north central US. The euro shows sfc temperatures in the -30's along the Candian border next thursday morning. I'm by no means forecasting that that will happen but its impressive nonetheless, especially considering it's not the 384 hours gfs.

[prinsburg_wx]

Looks like the fun should begin within the next couple of days. The latest models continue to show the eastern Pac ridge developing by this weekend with the mean trough developing over the central US lasting through at least the next 10-15 days. As long as the eastern Pac ridge stays put, especially combined with a -AO/-NAO, cold air should continue to make intrusions into the north central US. Models show, and the pattern looks to support clipper after clipper driving through the northern plains, with arctic highs dropping southward in their wake. In fact, there looks to be 2 systems that will bring accumulating snow to areas of the Dakotas and MN by the end of the weekend. Also, with the mean trough centered over the central US, I wouldn't be surprised to see an impressive system or two develop across the lower Mississippi valley and push up into the Great Lakes as well.

Looks like the first shot of fairly widespread below zero readings up around here may come overnight Sunday. Thereafter it looks likely that we'll see a new cold shot every few days. Any areas that are able to lay down a snowpack could possibly see temperatures rivaling last years coldest day (which obviously isn't all that impressive) before Christmas arrives. Granted it's a week out and I'm sure the models will moderate some in time, but glancing at tonight's 0z models shows some impressive cold air working into the north central US. The euro shows sfc temperatures in the -30's along the Candian border next thursday morning. I'm by no means forecasting that that will happen but its impressive nonetheless, especially considering it's not the 384 hours gfs.

20121206 12z euro backing way off on the big arctic chill for the northern plains later next week...not surprised as thats been the case so far in recent weeks that models show big cold only to back off in later runs. 12z gfs backed off some also with arctic cold. I wouldn't bank on anything with the models past 5 days including the so called "king euro". Anyway, still looking more active but the split flow might screw us up here for anything big.

[Srain]

EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD

202 PM EST THU DEC 06 2012

VALID 12Z SUN DEC 09 2012 - 12Z THU DEC 13 2012

THE MEDIUM RANGE PERIOD CONTINUES TO FEATURE A STABLE AND WELL

AGREED UPON LARGE SCALE PATTERN FEATURING AN ERN PAC MEAN RIDGE

AND POSITIVELY TILTED NOAM MEAN TROF WELL INTO NEXT WEEK. THERE

IS LOWER CONFIDENCE WITH INDIVIDUAL SHORTWAVES PROGRESSING AROUND

THE TOP OF AN AMPLIFIED ERN PACIFIC RIDGE AND CONTINUING INTO THE

DOWNSTREAM MEAN TROF...THOUGH ENOUGH CLUSTERING EXISTS TO IDENTIFY

THREE PRIMARY FEATURES LIKELY TO BE OF INTEREST THRU NEXT TUE.

THE LEADING SYSTEM WILL DEEPEN AS IT TRACKS FROM THE PLAINS/MS

VALLEY INTO ERN CANADA DURING DAYS 3-5 SUN-TUE. THE 00Z ECMWF

LEANS SLIGHTLY ON THE FASTER SIDE OF THE SPREAD WHILE THE 00Z AND

12Z UKMET RUNS REMAIN ON THE SLOWER SIDE. THE GEFS/ECMWF ENSEMBLE

MEANS HAVE BEEN FAIRLY STEADY IN DEPICTING AN INTERMEDIATE

SOLUTION AND ARE CERTAINLY WORTH SOME WEIGHTING IN THE FORECAST

GIVEN CURRENT SPREAD AND MODEL VARIABILITY OVER RECENT DAYS.

MULTI-DAY TRENDS LEAN A LITTLE FASTER AS A WHOLE SO PARTIAL

ACCOUNT WAS GIVEN TO THE 00Z GFS/ECMWF. THIS SOLUTION IS NOW

INCREASINGLY MUDDLED WITH THE LATEST 12Z ECMWF NOW SWITCHING TO A

SLOWER/MORE DEFINED LOW SOLUTION MORE IN VEIN WITH THE UKMET.

THIS SOLUTION WAS NOT DEPICTED IN HPC PROGS GIVEN THE MEAN

LONGWAVE FLOW SEEMS LESS THAN FAVORABLE AMID UNCERTAINTY...BUT IS

STILL IS A POSSIBLE SOLUTION THAT WOULD OFFER A MUCH WETTER PCPN

PATTERN.

[Srain]

I'm a bit more interested in the third in a series of short waves that has been suggested for several day now via the operational guidance. This feature has the potential to drop snow across Arizona and New Mexico with a Coastal low developing along the S Texas Coast providing for increased moisture and slightly better dynamics in the cold sector. It does appear we are in an active/stormy pattern with multiple opportunities for Winter Storm threats.