Texas/MX Obs And Discussion Thread.

[wxmx]

GFS pattern for the artic download around day 9+ is sucky for the S Plains, specially this far south, with the ridge centered around NW MX and SW US. The Euro is a lot better, with a deeper positive trough going trough the area, while a nice more high latitude ridge is out W. The Euro has been trending more towards the GFS lately wrt this 9-10+ artic outbreak, hopefully is time for the Euro to state who's the king.

[wxmx]

12z guidance still very divergent. The Euro keeps pushing the big artic outbreak to just after 10 days... and it now cutoffs a big low over NW MX/SW US, not buying any cutoff lows that far out...if only it would verify a bit farther south . GFS has been a bit more consistent lately... not much worth there other than some parts of far N TX.

[Srain]

12z guidance still very divergent. The Euro keeps pushing the big artic outbreak to just after 10 days... and it now cutoffs a big low over NW MX/SW US, not buying any cutoff lows that far out...if only it would verify a bit farther south . GFS has been a bit more consistent lately... not much worth there other than some parts of far N TX.

Just enough to keep my attention. I'm not real worried regarding the GFS at this point, the ensembles are starting to sniff this out.

[Srain]

12Z euro ensembles...

[Srain]

HGX:

HAVE FAVORED THE ECMWF WITH ITS DEPICTION OF ANOTHER COLD FRONT SAGGING

SOUTH LATE SATURDAY REACHING THE GULF BY SUNDAY MORNING. THIS

PATTERN FOR NEXT SUNDAY COULD BRING A SIGNIFICANT SNOW EVENT TO

THE WEST-CENTRAL PLAINS WHICH COULD MEAN LESS MODIFICATION FOR THE

AIRMASS SLIDING DOWN THROUGH THE PLAINS BY THE MIDDLE OF NEXT WEEK.

[Srain]

Nice disco from FWD this afternoon...

MONDAY NIGHT...THE POWERFUL UPPER TROUGH WILL ACTUALLY MOVE THRU

THE SOUTHERN PLAINS MONDAY NIGHT. AS IT PUSHES EAST THRU THE

REGION IT WILL SEND MORE OF A TRUE COLD FRONT SOUTHEAST THRU NORTH

TX. AS THE UPPER TROUGH APPROACHES MODELS CONTINUE TO QUICKLY

SATURATE THE MID TO UPPER LVLS OF THE TROPOSPHERE FROM 06Z TO 12Z

MONDAY NIGHT/EARLY TUESDAY MORNING. THIS SATURATION SEEMS TO BE

DUE TO STRONG FRONTOGENETIC FORCING AROUND THE H600 LEVEL. A CROSS

SECTION THRU NORTH TX ORIENTED NORTHWEST TO SOUTHEAST CONTINUES TO

SHOW THIS STRONG FRONTOGENETIC FORCING OCCURS WITHIN A NARROW

SLOPING BAROCLINIC ZONE THAT IS LOCATED NEAR THE BOUNDARY LAYER

OVER THE GOMEX AND SLOPES UP THRU THE H700 TO H550 LAYER OVER

NORTH TX FROM SOUTHEAST TO NORTHWEST. ABOVE THIS AXIS OF

FRONTOGENETIC FORCING MODELS CONTINUE TO SHOW A 100 TO 150 MB

THICK LAYER HAVING LOW STATIC STABILITY. THEREFORE WOULD EXPECT

THAT UPWARD VERTICAL MOTIONS ASSOCIATED WITH THE MID LEVEL FORCING

WILL BRING 150 MB OR SO OF STRONG LIFT OVER NORTH TX AFTER

MIDNIGHT MONDAY NIGHT. WITH AT LEAST SOME OF THIS LIFT OCCURRING

IN THE DENDRITIC GROWTH ZONE WOULD EXPECT THAT THIS LAYER WILL BE

AN EFFICIENT PRODUCER OF ICE CRYSTALS FOR A FEW HRS LATE MONDAY

NIGHT. AT THIS TIME THE SUB H700 LAYER OF THE ATMOSPHERE CONTINUES

TO LOOK DRY AND DOMINATED BY COLD AIR ADVECTION AND SUBSIDENCE.

WITH THIS IN MIND WOULD EXPECT PRECIPITATION FALLING OUT OF THE

MID LVL CLOUD DECK TO EVAPORATE/SUBLIMATE BEFORE REACHING THE SFC

MONDAY NIGHT. THEREFORE HAVE MAINTAINED A DRY FORECAST FOR MONDAY

NIGHT AT THIS TIME. IF THE LOWER TROPOSPHERE IS NOT AS DRY AS

FORECAST IT WOULD BE POSSIBLE FOR SOME SPRINKLES OF FLURRIES TO

REACH THE SFC MONDAY NIGHT.

[msp]

Finally got back in town... Feels nice after the Midwest cold.

64/60 now and tomorrow looks to be the last warm day for a little while. I'm hoping we can squeeze some precip out of it, but it's probably going to mostly stay east.

[Srain]

Here is the HPC morning Prelim discussion concerning the overnight models and the differences between them...still more questions than answers...

PRELIMINARY EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

319 AM EST MON NOV 29 2010

VALID 12Z FRI DEC 03 2010 - 12Z MON DEC 06 2010

DEEPENING CYCLONES IN THE NORTHEAST PACIFIC AND OFFSHORE NEW

ENGLAND/ATLANTIC CANADA NORMALLY IMPLIES RIDGING IN BETWEEN. NOT

SO THIS PERIOD AS A SYSTEM FROM THE EASTERN PACIFIC DIVES

SOUTHEAST INTO CALIFORNIA AND PROGRESSES ACROSS THE ROCKIES AHEAD

OF A NARROW AMPLIFYING RIDGE...SQUEEZING THE RIDGE ACROSS THE

SOUTH SLOWLY OUT OF EXISTENCE BY MID NEXT WEEK. THE GUIDANCE IS

IN VERY GOOD AGREEMENT ON MOST OF THE FORECAST THIS PERIOD. SINCE

THE 00Z GFS IS IN BEST AGREEMENT WITH THE ENSEMBLE MEANS ON THE

LARGE SCALE...USED A 00Z GFS/00Z GEFS MEAN COMPROMISE/BLEND AS A

STARTING POINT FOR THE PRESSURES.

THE 64000 DOLLAR QUESTION CONTINUES TO CIRCLE AROUND WHAT WILL

HAPPEN WITH AN INTERMEDIATE SHORTWAVE PROGRESSING INTO THE PACIFIC

NORTHWEST EARLY ON WHICH MOVES OVER A PRE-EXISTING BROAD RIDGE

LOCATED OVER THE SOUTHERN STATES. OF ALL THE GUIDANCE...THE 00Z

CANADIAN HAS MAINTAINED THE BEST MULTI-DAY CONTINUITY WITH THIS

SYSTEM...THOUGH ITS SOLUTION IS SLOWER THAN THE ENSEMBLE MEANS

SUGGEST...SO FROM THAT STANDPOINT IT COULD NOT BE USED EARLY THIS

MORNING. THE 00Z GFS DAMPENS THE PACIFIC SHORTWAVE OUT OF

EXISTENCE WHILE THE 00Z ECMWF/00Z CANADIAN MOVE THIS SHORTWAVE

THROUGH THE RIDGE...DAMPENING THE RIDGE OUT OF EXISTENCE. IF

THERE WERE A POLAR VORTEX OVER HUDSON BAY...THE ECMWF/CANADIAN

SOLUTION WOULD HAVE MORE MERIT. HOWEVER...THE GUIDANCE HAS THE

VORTEX CENTERED OVER NUNAVUT...SO ITS INFLUENCE ON THE FLOW OVER

THE LOWER 48 SHOULD BE MINIMAL IF THE CURRENT GUIDANCE IS CORRECT

IN ITS POSITION AS WELL AS THE POSITION/STRENGTH OF THE DEEP

CYCLONE NEAR NEW ENGLAND. BELIEVE THE 00Z CANADIAN/00Z ECMWF ARE

TOO STRONG AND THE 00Z GFS IS TOO WEAK WITH THIS SHORTWAVE...SO

USED THE 12Z GLOBAL ENSEMBLE CLUSTERING TO MOVE THIS SYSTEM ON AN

INTERMEDIATE TRACK WHICH RESPECTS THE RIDGING MORE THAN THE

CANADIAN/ECMWF ADVERTISE...TAKING A FRONTAL WAVE TOWARDS MICHIGAN

BEFORE IT SHEARS OUT ON THE WESTERN SIDE OF THE NORTHWEST ATLANTIC

CYCLONE. THIS ENDS UP WITH A SET OF PRESSURES THAT MAINTAIN

REASONABLE CONTINUITY...BUT CONFIDENCE IS NO BETTER THAN AVERAGE

IN THIS PREFERENCE.

GGEM (Canadian)...

Euro...

GFS...

HGX...

THE RIDGE BEGINS TO BREAK DOWN

NEXT MONDAY AS AN UPPER TROUGH TAKES SHAPE OVER THE SOUTHERN

ROCKIES. THE TROUGH IS EXPECTED TO MOVE ACROSS THE SOUTHERN PLAINS

BRINGING ANOTHER CHANCE OF RAIN NEXT MON/TUES WITH SEVERAL LONG

RANGE MODELS HINTING AT A MUCH COLDER AIR MASS FOR EARLY NEXT

WEEK.

Dallas/Ft Worth...

LOOKING AT THE BIGGER PICTURE...UPPER LEVEL PATTERN WILL FEATURE

A BLOCK FROM GREENLAND SOUTHWARD WITH LONGWAVE TROUGHS LOCATED

ALONG THE EAST COAST AND ACROSS THE NE PACIFIC OCEAN. STATIONARY

LOW PRESSURES AT EACH EDGE OF THE CONTINENT WILL FOSTER THE GROWTH

OF A LARGE SPRAWLING HIGH PRESSURE CELL ACROSS CANADA INTO THE

CENTRAL US BY EARLY NEXT WEEK. THIS HIGH SHOULD EXPAND INTO THE

REGION ALLOWING FOR PROLONGED NORTHERLY FLOW TO TAP INTO SOME

CANADIAN AIR AND GRADUALLY BRING IT INTO NORTH TEXAS. THUS IT IS

WITH REASONABLY HIGH CONFIDENCE THAT NEXT WEEK WILL FEATURE A

PERIOD OF COOLER THAN NORMAL TEMPS. MODELS ARE STILL DIFFERING ON

THE DETAILS...WITH THE ECMWF SUGGESTING THIS FRONT WILL ARRIVE

SATURDAY WITH GRADUAL COOLING INTO THE NEXT WEEK...AND THE GFS IS

DELAYING THE COOL DOWN UNTIL AFTER THE WEEKEND. THE CANADIAN/UKMET

AND MOST OF THE GFS ENSEMBLE MEMBERS ARE IN AGREEMENT WITH THE

OPERATIONAL GFS AND THUS HAVE KEPT HIGHS WARM SATURDAY...BUT DID

START TO TREND THINGS COOLER SUNDAY AND ESPECIALLY SO ON MONDAY.

OTHERWISE THE ECMWF ALSO REMAINS THE OUTLIER WITH THE STRENGTH OF

A MON-TUE UPPER LEVEL WAVE...BUT IT DID TREND TOWARD THE WEAKER

AND LESS AMPLIFIED FORECASTS OF THE GFS/UKMET/CANADIAN AND

MAJORITY OF THE ENSEMBLE MEMBERS. THERE IS SOME POTENTIAL FOR

PRECIPITATION WITH THIS SYSTEM AND WITH THE COLUMN COOLING IT IS

POSSIBLE IT MAY BE OF FROZEN VARIETY ALONG THE RED RIVER. THE

UPPER PATTERN DOES FIT INTO A CLIMATOLOGICAL SIGNAL FOR SNOW...BUT

ONE THAT ONLY PRODUCED SIGNIFICANT SNOWS NORTH OF I-20 WITH

TEMPERATURE PROFILES USUALLY TOO WARM ACROSS NORTH TEXAS. STILL A

LONG WAY OUT AND EXPECT MODELS TO CONTINUE TO WAFFLE...SO

CONFIDENCE IN WINTER PRECIPITATION REMAINS VERY LOW.

Norman, OK...

NEXT WEEKEND IS TOUGH TO CALL. IT ALL DEPENDS ON HOW THE VARIOUS

SYSTEMS INTERACT OFF THE W COAST LATE IN THE WEEK... AND ONE OF

THOSE IS CURRENTLY N OF JAPAN. ECMWF CONTINUES TO SHOW A MORE

AMPLIFIED TROUGH COMING OUT INTO THE PACIFIC NW AND MOVING

THROUGH THE NORTHERN STATES LATE IN THE WEEK... AND DRIVES A

CANADIAN AIRMASS S THROUGH THE PLAINS IN ITS WAKE. GFS SHOWS NO

SUCH TROUGH... AND THUS DELAYS ANY SERIOUS COLD INTRUSION IN THE S

PLAINS UNTIL LATE IN THE WEEKEND OR EARLY NEXT WEEK. THE MOST

REASONABLE SCENARIO MAY BE IN BETWEEN... WITH A WEAKER UPPER

TROUGH AND A SLOWER... MORE TEMPERED INTRUSION OF COLD AIR INTO

OK NEXT WEEKEND THAN SHOWN BY THE ECMWF. THIS IS THE WAY HPC IS

LEANING... SEE THEIR PRELIM MED-RANGE DISCUSSION AND EARLY DAY5-7

SFC PROGS... AND IS SUPPORTED TO SOME DEGREE BY THE GEFS. A LOT OF

BUST POTENTIAL ON TEMPERATURES SAT-SUN DEPENDING ON HOW MUCH AND

HOW FAST THE COLDER AIR TAKES CHARGE.

WHATEVER THE CASE MAY BE... POTENTIAL STILL EXISTS FOR MUCH COLDER

AIR AND POSSIBLE SNOW/ICE EARLY NEXT WEEK... ESPECIALLY MON-TUE

DEC 6-7. DETAILS MUCH TOO UNCERTAIN TO OFFER ANY SPECIFICS THIS

FAR OUT.

Dodge City, KS...

DAYS 3-7...

THERE IS CONSIDERABLE UNCERTAINTY TOWARDS THE SECOND WEEK OF

DECEMBER (TOWARDS THE END OF THE FORECAST PERIOD). MODELS HAVE BEEN

FLIP FLOPPING ALL OVER THE PLACE. FOR EXAMPLE, THE 12Z OPERATIONAL

RUN OF THE ECMWF DEVELOPS A HUGE CUTOFF LOW ACROSS THE DESERT

SOUTHWEST ON THE 6TH WHICH WOULD RAISE EYEBROWS FOR THE POTENTIAL

FOR WINTER TYPE PRECIPITATION ACROSS SOUTHWESTERN KANSAS. THE 00Z

ECMWF IS COMPLETELY DIFFERENT AND MUCH MORE PROGRESSIVE WITH UPPER

LEVEL DYNAMICS. COMPARING THIS WITH THE 00Z GFS DOES INDICATE THE

POTENTIAL FOR MORE UNSETTLED WEATHER TOWARDS THE END OF THE FORECAST

PERIOD AS THE GFS ALSO HINTS AT A SHORTWAVE DIVING DOWN FROM THE

NORTHWEST. THE ATMOSPHERIC COLUMN DURING THIS PERIOD COULD BE COLD

ENOUGH FOR SNOW. THE PNA INDEX IS ALSO FORECAST TO GO NEGATIVE

TOWARDS THE MIDDLE OF DECEMBER WHICH WOULD FAVOR LOWER 500 HPA

HEIGHTS OUT WEST. THE NCEP ENSEMBLE MEAN ALSO FAVORS THE DEVELOPMENT

OF A TROUGH OUT WEST ALTHOUGH THE 12Z ECMWF ENSEMBLE MEAN HAS THE

STORM TRACK FURTHER EAST. AS A RESULT OF THE GENERAL HINT AND TREND

TOWARDS A MORE ACTIVE STORM TRACK, I HAVE INSERTED SILENT POPS IN

THE GRIDS FROM SUNDAY ON. OF COURSE, CONFIDENCE IS VERY LOW AND TO

JUMP ON ANY PARTICULAR MODEL SOLUTION AT THIS POINT WOULD BE SILLY,

HOWEVER A TREND TO COOLER AND POSSIBLY WETTER WEATHER SEEMS

APPROPRIATE AT THIS POINT IN TIME. THESE GHOST POPS ALSO MATCH

BETTER WITH OUR WFO NEIGHBORS, PARTICULARLY TO THE EAST. LASTLY,

BECAUSE OF FRONTAL TIMING DIFFERENCES, I USED CONSALL FOR GRID

MODIFICATIONS. THIS SEEMED TO BE IN THE MIDDLE GROUND FROM THE

EXTREMELY COLD GFS TO THE MORE MODERATE ECMWF AS A SIGNIFICANT COLD

FRONT AND ASSOCIATED ARCTIC MASS DIVES SOUTH TOWARDS DAY 8, HOWEVER

BOTH MODELS DO POOR WITH ARCTIC AIRMASSES SO THE POTENTIAL FOR

TEMPERATURE BUSTS IS FAIRLY HIGH ATTM.

[Srain]

Updated HPC:

CENTRAL/EASTERN US...

THE PRIMARY UNCERTAINTY CONTINUES TO REVOLVE AROUND WHAT WILL

HAPPEN WITH A MID LEVEL SHORTWAVE PROGRESSING FROM THE NORTHERN

ROCKIES ACROSS THE CENTRAL PLAINS/MS VALLEY AND POINTS FURTHER

EAST.

THE LARGE SCALE PATTERN FEATURES A PERSISTENT TROUGH OVER NEW

ENGLAND AND COASTAL TO OFFSHORE WATERS...AS A HIGH AMPLITUDE RIDGE

ALONG THE LATITUDE OF GREENLAND ACTS AS A BLOCK. THIS LEADS TO

PERSISTENT COLD CONDITIONS IN THE NORTHEAST US.

ANOTHER CLOSED LOW EXISTS OVER NORTH CENTRAL CANADA WITH CONFLUENT

FLOW BETWEEN THE CYCLONIC CIRCULATION IN CENTRAL CANADA AND A MEAN

500 MB RIDGE DRIFTING EAST ACROSS MEXICO. THE 00Z ECMWF AND

CANADIAN GLOBAL MODELS SHOW A MORE AMPLIFIED 850-500 MB WAVE

MOVING EAST-SOUTHEAST IN THE CONFLUENT FLOW AND THE 00Z GFS AND

UKMET MORE SUPPRESSED. THE NCEP AND ECMWF ENSEMBLE MEMBERS

GENERALLY SHOW A LOWER AMPLITUDE WAVE THAN THE OPERATIONAL ECMWF

AND A MEAN SOLUTION WAS USED TO MITIGATE THE DIFFERENCES BETWEEN

THE TWO DIFFERENT APPROACHES TO THIS SYSTEM. THE 06Z GFS BECOMES

AN OUTLIER 06-12Z SAT IN THE NORTHERN PLAINS WITH A SEPARATE LOW

THAT MIGRATES TOWARDS THE GREAT LAKES...WITH THE PRIMARY NORTHERN

STREAM CLOSED 500 MB LOW DEVELOPING IN THE LAKES BY SUNDAY 05 DEC.

CONFIDENCE IS LOW WITH THIS LARGE OF A RUN TO RUN CHANGE AND

DIFFERENCE FROM 00-06Z ENSEMBLE MEMBER/MEAN SOLUTIONS.

THE MODELS/ENSEMBLES SHOW THE 500 MB TROUGH CROSSING THE SOUTHERN

ROCKIES ON

SUN AND THEN SOUTHERN PLAINS ON MON 06 DEC. LOW PRESSURE SHOULD

DEVELOP IN THE SOUTHERN PLAINS TO GULF COAST AS THIS WAVE MOVES

EAST. CONTINUING TIMING/PHASING DIFFERENCES AMONG THE

MODELS/MEANS PERSIST...BUT THE 500 MB WAVE HOLDS CONTINUITY IN THE

ECMWF/GFS/CANADIAN MODELS AND NCEP/ECMWF ENSEMBLE MEANS.

AGAIN...THE MEAN SOLUTION WAS USED TO DECIDE ON THE

DIFFERENCES....WITH GOOD AGREEMENT AMONG THE 00-06Z GEFS MEAN/00Z

ECMWF ENSEMBLE MEAN IN SPITE OF A LARGE SPREAD IN THE ECMWF

ENSEMBLE SOLUTIONS REGARDING WHETHER/WHERE A CLOSED LOW DEVELOPS

WITHIN THIS LG SCALE TROUGH.

[msp]

CF soon to pass through here. 72/43 in temple and 79/66 in CLL. should be a nice cooldown but will unfortunately end these showers.

[Srain]

[wxmx]

Wow @12z Euro. 0°C 850mb temps down to just north of Veracruz...that's a classical super amplified, very positive tilted trough/W coast to Greenland very positive height anomalies/big Canadian artic high... It should also be quite moist for N MX and S TX. Too bad this will change for the next run

[Flexo]

Wow @12z Euro. 0°C 850mb temps down to just north of Veracruz...that's a classical super amplified, very positive tilted trough/W coast to Greenland very positive height anomalies/big Canadian artic high... It should also be quite moist for N MX and S TX. Too bad this will change for the next run

Looks like it is dragging a lot of energy through the SW creating this rather odd look to the trough... One big cut off over the SW, and then later over Texas. Looks like a bias to me, but whatevs. Me likey (for now)

HGX apparently likes the Euro, too

AFTER THE BLUSTERY TUESDAY THE 1029MB HIGH WILL BE OVERHEAD

WEDNESDAY MORNING SO WILL HAVE ANOTHER CHILLY MORNING IN THE 30 TO

35 DEGREE RANGE FOR THE INLAND AREAS. THE HIGH TO MOVE EAST AND

RETURN FLOW GETS UNDERWAY THURSDAY STRENGTHENING FRIDAY SO A

PLEASANT WARM UP WILL OCCUR. THEN THINGS GET DICEY. GFS HAS BEEN

BOUNCING AROUND A LOT LATELY WITH ITS SOLUTIONS IN THE WESTERN

U.S. AND ECMWF HAS BEEN TRENDING STRONGER WITH AN UPPER LOW MOVING

INTO THE WEST. HAVE TRENDED THE FORECAST TOWARD A STRONGER

SOLUTION BUT NOT BITING OFF ON IT ENTIRELY YET. SO FOR NOW EXPECT

A COLD FRONT TO DROP IN SATURDAY DURING THE DAY SLIDING EAST WITH

OVERRUNNING AND WARM FRONT SETTING UP BY MONDAY. VERY COLD AIR

DROPPING SOUTH THROUGH THE PLAINS. GETTING MORE CONFIDENT THAT A

SNOW EVENT SHAPING UP FOR THE SOUTHERN PLAINS AND NORTH TEXAS BY

TUESDAY. THIS SHOULD LEAD TO A CLOUDY...COLD AND WET END TO THE

FORECAST FOR MONDAY AND TUESDAY IN SETX.

[msp]

my interest is officially piqued. hgx dropped highs for monday to 50F.

i'm not familiar with the climo in these parts really at all, but that low and attendant H85 0C line on the euro seem ridiculously far out over the GoM for early dec. is the situation as depicted really that anomalous?

[wxmx]

Looks like it is dragging a lot of energy through the SW creating this rather odd look to the trough... One big cut off over the SW, and then later over Texas. Looks like a bias to me, but whatevs. Me likey (for now)

HGX apparently likes the Euro, too

AFTER THE BLUSTERY TUESDAY THE 1029MB HIGH WILL BE OVERHEAD

WEDNESDAY MORNING SO WILL HAVE ANOTHER CHILLY MORNING IN THE 30 TO

35 DEGREE RANGE FOR THE INLAND AREAS. THE HIGH TO MOVE EAST AND

RETURN FLOW GETS UNDERWAY THURSDAY STRENGTHENING FRIDAY SO A

PLEASANT WARM UP WILL OCCUR. THEN THINGS GET DICEY. GFS HAS BEEN

BOUNCING AROUND A LOT LATELY WITH ITS SOLUTIONS IN THE WESTERN

U.S. AND ECMWF HAS BEEN TRENDING STRONGER WITH AN UPPER LOW MOVING

INTO THE WEST. HAVE TRENDED THE FORECAST TOWARD A STRONGER

SOLUTION BUT NOT BITING OFF ON IT ENTIRELY YET. SO FOR NOW EXPECT

A COLD FRONT TO DROP IN SATURDAY DURING THE DAY SLIDING EAST WITH

OVERRUNNING AND WARM FRONT SETTING UP BY MONDAY. VERY COLD AIR

DROPPING SOUTH THROUGH THE PLAINS. GETTING MORE CONFIDENT THAT A

SNOW EVENT SHAPING UP FOR THE SOUTHERN PLAINS AND NORTH TEXAS BY

TUESDAY. THIS SHOULD LEAD TO A CLOUDY...COLD AND WET END TO THE

FORECAST FOR MONDAY AND TUESDAY IN SETX.

Oh yes, a bias it is for sure.

It looks a lot like this

Rather early in December also...but the ENSO was a little different.

[wxmx]

my interest is officially piqued. hgx dropped highs for monday to 50F.

i'm not familiar with the climo in these parts really at all, but that low and attendant H85 0C line on the euro seem ridiculously far out over the GoM for early dec. is the situation as depicted really that anomalous?

The best teleconnector for cold this far south (higher correlation) is not the AO, NAO or PNA, but the ridging in the US W coast, specially if we have an s/w that's connected to a piece of the PV to the NE (positive tilt to the trough)

[wxmx]

Just to show how anomalous it would be

It shows -7°C 850mb temps here... there hasn't been that low temps since...oh well, I don't even remember, even the big artic outbreaks are rather shallow (colder at surface than 850mb).

[Flexo]

The best teleconnector for cold this far south (higher correlation) is not the AO, NAO or PNA, but the ridging in the US W coast, specially if we have an s/w that's connected to a piece of the PV to the NE (positive tilt to the trough)

Look at the difference between the 18z GFS and 12z Euro, lol

The 18z GFS completely loses that system in the Pacific as it is absorbed by the large GOA trough

[wxmx]

Look at the difference between the 18z GFS and 12z Euro, lol

The 18z GFS completely loses that system in the Pacific as it is absorbed by the large GOA trough

Yep...there's no love with the GFS... garden variety dry cool down.

[bubba hotep]

I would feel better if the GFS would at least start to trend towards the Euro. I followed too many bust during my time in the mid atlantic and will remain pessimistic!

[wxmx]

I would feel better if the GFS would at least start to trend towards the Euro. I followed too many bust during my time in the mid atlantic and will remain pessimistic!

That's the way it should be...keep expectations low. There's little support for the Euro's extreme solution yet. The key is, as Flexo pointed out, if we can get some STJ energy flowing...there's going to be amplification, all models show it, but the Euro is the extreme outlier.

[Srain]

I would feel better if the GFS would at least start to trend towards the Euro. I followed too many bust during my time in the mid atlantic and will remain pessimistic!

I agree. The GFS sniffed the pattern out days ago and may have lost it for now.

That's the way it should be...keep expectations low. There's little support for the Euro's extreme solution yet. The key is, as Flexo pointed out, if we can get some STJ energy flowing...there's going to be amplification, all models show it, but the Euro is the extreme outlier.

The S TX Coastal will be key, if correct. So many things have to be just right to get a measureable snowfall in this part of the world, IMO.

[Flexo]

It's kind of hard to tell what is going to happen when the GFS is changing like this run to run

[Flexo]

Congrats msp!

The run would probably give Houston a chance of some snow as well...

[somethingfunny]

If I can get 3 reliable (00z and 12z) runs in a row of the GFS showing the low.... I'll buy into this.

[somethingfunny]

From Fort Worth this morning.....

THE SECOND PART OF THIS FORECAST CONCERNS A PACIFIC SHORTWAVE THAT

SHOULD APPROACH THE SOUTHERN PLAINS EARLY NEXT WEEK. WITH COLD AIR

IN PLACE...ANY DISTURBANCE WOULD HAVE TO BE WATCHED FOR POTENTIAL

WINTER PRECIP. EVEN THOUGH THE UPPER FLOW REMAINS BLOCKED NORTH

40N LATITUDE...AN ACTIVE SUBTROPICAL JET ACROSS THE SOUTHERN CONUS

SHOULD ENSURE A PROGRESSIVE MOTION TO PACIFIC SHORTWAVE ENERGY.

MODEL GUIDANCE REMAINS IN POOR AGREEMENT AND ENSEMBLE MEMBERS ONLY

ADD MORE POSSIBLE SCENARIOS. THE ECMWF REMAINS THE MOST AGGRESSIVE WITH WINTER WEATHER NEXT TUESDAY...SHOWING A CLOSED/POTENT UPPERLOW...BUT IS OFTEN TOO STRONG WITH THESE FEATURES BEYOND DAY 5.THE 0Z OPERATIONAL GFS HAS A MUCH WEAKER SOLUTION THAT WOULD BRING NO PRECIP TO OUR AREA. THE GFS SOLUTION SEEMS UNLIKELY...HAVING

LITTLE ENSEMBLE SUPPORT OR BACKING FROM THE CANADIAN/UKMET. SINCE

MODELS ARE OFFERING NO HELP...IT IS USEFUL TO NOTE THAT THERE IS A

CLIMATOLOGICAL SIGNAL FOR THIS TYPE OF UPPER PATTERN TO PRODUCE

SNOW ACROSS THE NORTHERN CWA. MOST OF THE PREVIOUS EVENTS SHOWED

THESE PACIFIC SHORTWAVES CAME ACROSS AS OPEN TROUGHS AND NOT

CLOSED LOWS...AGAIN SUGGESTING THE ECMWF IS OVERDONE. CLIMO ALSO

SAYS THIS PATTERN HAS A HARD TIME GETTING THE ENTIRE COLUMN COOLED

BELOW FREEZING AS POLAR TRAJECTORY IS NOT OPTIMAL...BUT OBVIOUSLY

THIS WAS/IS MOST LIKELY TO OCCUR ACROSS THE NORTHERN ZONES. EITHER

WAY THERE REMAINS A LOT OF UNCERTAINTY AND ITS UNLIKELY MODELS

WILL SETTLE ON A SOLUTION FOR AT LEAST A FEW MORE DAYS. IF I HAD

TO ASSIGN A CHANCE FOR WINTER WEATHER IN THE CWA AT THIS POINT...I

WOULD SAY ABOUT 1 OR 2 CHANCES IN 20.

[Srain]

HPC:

THE GLOBAL DETERMINISTIC AND ENSEMBLE GUIDANCE IS IN GOOD

AGREEMENT THAT A DEEP CYCLONE WILL BE SLOWLY PROGRESSING THROUGH

THE NORTHEAST PACIFIC...AND THAT A NEGATIVELY TILTED TROUGH WITH

AN EMBEDDED DEEP CYCLONE WILL LURK NEAR NEW ENGLAND AND ATLANTIC

CANADA THROUGH THE PERIOD /THE 00Z CANADIAN HAS ISSUES WITH THIS

LATTER SYSTEM DUE TO ITS UNIQUE SOLUTION IN CENTRAL CANADA EARLY

TO MID NEXT WEEK/.

THERE ARE PAIR OF FORECAST ISSUES EARLY THIS MORNING. THE FIRST

ISSUE REVOLVES AROUND A PACIFIC SHORTWAVE MOVING OVER THE TOP OF

THE BROAD/INCREASINGLY STRONG RIDGE CENTERED ACROSS THE SOUTHERN

STATES WHICH MOVES NEAR THE US/CANADIAN BORDER BEFORE DIVING

EAST-SOUTHEAST INTO THE MID-ATLANTIC STATES. THE 00Z CANADIAN/00Z

ECMWF MOVE THE SYSTEM THROUGH THE NORTH AND EAST ABOUT A DAY

QUICKER THAN THE 00Z GFS...AS THE GFS USES ADDITIONAL NORTHERN

STREAM ENERGY MOVING THROUGH WESTERN CANADA TO SLOW ITS PACE AS IT

MOVES THROUGH AN OTHERWISE QUICK QUASI-ZONAL/SUPERGEOSTROPHIC

FLOW. ALSO...BY THE TIME IS MOVES NEAR THE MID-ATLANTIC

STATES...THE GFS BRINGS 500 HPA HEIGHTS 4.5-5 STANDARD DEVIATIONS

BELOW NORMAL FOR THIS TIME OF THE YEAR BETWEEN CHARLESTON SC AND

JACKSONVILLE FL...WHICH IS IMPROBABLE. SINCE THE ECMWF ENSEMBLE

MEMBER TIMING HAS BEEN REASONABLY CONSISTENT OVER ITS PAST FEW

DAYS OF RUNS...AND INDICATE A QUICKER PROGRESSION...WILL CONTINUE

TO GO WITH THIS IDEA BY FAVORING A 00Z ECMWF-LIKE SOLUTION...WHICH

LOOKS MUCH MORE PLAUSIBLE THAN ITS PRIOR COUPLE DAYS OF RUNS.

THE SECOND ISSUE INVOLVES A POTENTIALLY CLOSED LOW MOVING THROUGH

THE SOUTHWEST...WHICH BOTH THE 00Z CANADIAN/00Z ECMWF ADVERTISE.

THE 00Z GFS HAS A CLOSED LOW WHICH IT DEVELOPS MUCH FARTHER

OFFSHORE THE SOUTHERN CALIFORNIA COAST...WHICH TAKES AN EXTRA

COUPLE DAYS TO GET INTO THE SOUTHWEST. THE GFS SOLUTION IS SLOWER

THAN THE EITHER CLUSTER OF THE BIMODAL 00Z GEFS MEAN AND MUCH

SLOWER THAN THE 12Z ECMWF ENSEMBLE MEAN SOLUTION. A SLOWLY

PROGRESSIVE NORTHERN STREAM RIDGE IN SOUTHWEST CANADA FAVORS A

PROGRESSIVE CLOSED CYCLONE 20 DEGREES UNDER ITS BASE MOVING

THROUGH THE SOUTHWEST...SO CONFIDENCE IS HIGHER THAN NORMAL IN ITS

EXISTENCE...BUT TIMING IS AN ISSUE...AS IS USUALLY THE CASE LATE

IN THE MEDIUM RANGE PERIOD. SINCE THE CLOSED MEMBERS OF THE 12Z

GEFS MEAN /USING 5520 METER 500 HPA HEIGHT LINE SPAGHETTIS/ WERE

IN LINE WITH A BULK OF THE 12Z ECMWF ENSEMBLE MEMBERS...AND THE

NORTHERN STREAM RIDGE IS ONLY SLOWLY PROGRESSIVE...THINK A QUICKER

PROGRESSION OF THE CLOSED LOW IS ADVISABLE...WHICH IS BEST IN LINE

WITH THE 00Z CANADIAN SOLUTION. THIS FITS INTO THE 00Z GEFS

MEAN/00Z ECMWF COMPROMISE PREFERENCE QUITE WELL.

[Srain]

Seeing many reports of sleet from the Lake Livingston area and points N and E as the Upper Air disturbance moves away.

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE SHREVEPORT LA

616 AM CST TUE NOV 30 2010

.UPDATE...

TO INCLUDE OCCASIONAL SLEET AND LIGHT RAIN THIS MORNING WITH MORE

THAN ONE REPORT OF LIGHT...MELTY SLEET. TWEAKED SKY AND POP/WX.

[msp]

Congrats msp!

first time that sentence has been said about a texas snowstorm.

interesting that lake livingston was reporting some sleety precip this morning. we got nothing here but overcast skies and a low of 48F.

not seeing too much warming today. if the sun wasn't out, this 58F and windy would feel awful.

saw the red flag warning too. winds here gusting out of the N at 35, and the RH has fallen to 33% and should continue its downward trend as we warm.

[TrekkerCC]

NWS Ft. Worth Office wrote:

.DISCUSSION...

WE SHOULD HAVE A FAIRLY WIDESPREAD FREEZE WEDNESDAY MORNING...AND

THEN THE WEEK WILL SEE A SLOW WARM UP WITH TEMPERATURES SATURDAY

IN THE 70S AT MANY LOCATIONS. GFS/ECMWF HAVE DECENT AGREEMENT ON

COLD FRONTAL PASSAGE EITHER LATE SATURDAY NIGHT OR SUNDAY

MORNING...SO HAVE COOLED SUNDAY TEMPERATURES DOWN. COLD AIR THEN

REMAINS IN PLACE THROUGH DAY SEVEN.

THE BIG QUESTION ABOUT A WINTER EVENT OVER NORTH TEXAS REMAINS ON

THE TABLE. ONCE AGAIN THE ECMWF HAS CHANGED CONSIDERABLY...WITH

THE 00Z RUN PRODUCING NEAR RECORD SNOWS OVER NORTH TEXAS

TUESDAY...AND THE NEW 12Z RUN GIVING US A DUSTING. THE OPERATIONAL

GFS TAKES THE SHORT WAVE ENERGY FARTHER NORTH...WITH ANY WINTER

PRECIP LIKELY REMAINING IN KANSAS/OKLAHOMA. THAT IS PRETTY MUCH

THE SOLUTION IT GAVE YESTERDAY...AND GIVES ME A MORE CONFIDENCE

IN THE GFS OVER THE ERRATIC ECMWF.

THE GFS ENSEMBLE SPAGHETTI PLOTS BEGIN TO DIVERGE QUICKLY AFTER

SATURDAY MORNING. THE MEMBERS AGREE THAT AN UPPER LOW WILL

DEVELOP OVER EASTERN PACIFIC FRIDAY...BUT THE TRACKS OF THE

SYSTEM ARE QUITE DIVERGENT AND ONLY TWO MEMBERS OF THE 12 WE SEE

IN OUR SOFTWARE FORECAST ANY SNOW OVER TEXAS. THIS IS LESS THAN 20

PERCENT OF THE MEMBERS SO THE CONSENSUS IS THAT NO SNOW IS EXPECTED.

IS WINTER WEATHER POSSIBLE NEXT WEEK--YES. IS IT PROBABLE--NOT

YET. WHAT REMAINS PROBABLE/EXPECTED IS A COOL DOWN...A MAJORITY OF

ENSEMBLE MEMBERS/THE OPERATIONAL GFS/AND THE ECMWF ALL FORECAST

COOLER WEATHER NEXT WEEK. THIS TREND IS IN OUR FORECAST...BUT IT

IS TOO EARLY TO SAY YES TO A WINTER EVENT.

Ft. Worth office in its discussion is noting the uncertainty, but essentially, they are saying it is possible-but-not-probable that a winter weather event will occur early next week for North Texas. The ECMWF 12z run no longer has the closed upper-level low solution it had last night . Since climatology (La Nina year) is against us, it might be a non-event much like the GFS projections are showing.