Texas Fall-2014

[Wntrwthrguy]

Great write-ups regarding the weather across the state!

Is there even a slight possibility that the Austin area will see winter precip Sunday night? If so, what should we be looking/hoping for in the models for that to happen?

[Ntxw]

Freeze number 2 for DFW. Looks like wxman57 gets his freeze tomorrow morning.

[Portastorm]

A chilly 34.8 degrees here at the PWC. It also appears that our cyberwinter enthusiast program did a number on that 0z GFS.

[Tireman4]

12Z GFS is predicting 29F at Bush airport (IAH) on Tuesday morning as the second Arctic high settles in over TX. Fine with me, as I have Nov. 21st as the first freeze date in our office contest and no one has an earlier date. I've been trying to win one of these contests for 15+ years. Almost won the first cold front contest but the required 49F dew point at IAH didn't occur until 1 hour too late for me to win.

So, to help things along I've temporarily change my avatar to something that might encourage the cold air this weekend & early next week.

What in the Sam Hill? Not again. You did this last year, then you went bi-polar during mid Winter. I will say, it was funny. You were arguing with yourself. Giving conflicting forecasts. LOL The heaters I bought should be at your office Friday sir.

[ronyan]

I woke up this morning to icy cold floors, 36.9F here within a few miles of the coast. We busted the forecast low by a good 4 degrees. I would say wxman57 has some money coming tonight if the skies clear a little.

[SouthernMet]

FORECAST SOUNDINGS DO INDICATE THAT CONDITIONAL INSTABILITY EXISTS
IN THE DENDRITIC GROWTH ZONE (-12 TO -18 DEG C LAYER) ALOFT...SO
THERE CERTAINLY IS THE POTENTIAL FOR MESOSCALE ENHANCEMENT
(BANDING) IF SUFFICIENT CONDITIONS ARE MET.

[hriverajr]

Well after this extended cold snap looks like moderation later next week, but perhaps an increasing opportunity for precipitation according to the models.

AO and EPO predicted to go positive.

[Ntxw]

I agree, relaxation of the pattern in the 6-10 day frame, but still a long way to go to get there. Late weekend cold front looks just as potent and keeps it just as cold. Im still seeing stormy signs for thanksgiving week.

A major SSW may be in the works up in the stratosphere for December

[CYCLONE MIKE]

Sitting at a balmy 38 right now south of baton rouge with light rain. Depending on which radar site one used earlier this morning some were even showing some kind of winter mix on the northern edge. Not even forecasted to get out of the 40's today and under freeze warnings for tonight and tomorrow night. This is pretty insane.

[ndale]

An excerpt from the EWX forecast regarding Sunday night:

MOST OF THE PRECIP TYPE WOULD REMAIN LIQUID...BEFORE
PRECIP CHANCES SHUT OFF MONDAY MORNING AS FORCING MOVES EAST.
HOWEVER...ACROSS THE FAR NORTHERN HILL COUNTRY (GILLESPIE...LLANO...
BURNET COUNTIES) THERE MAY BE A SMALL WINDOW FOR LIGHT SNOW TO MIX
IN EARLY MORNING.

[TeamPlayersBlue]

First thing, absolutely fantastic write ups gentlemen. So educational.
Last nights rain caught me off guard. If our wet bulb temp was a couple degrees lower, we would have had a big problem here in SE Tx. Looking at the models, it looks like having a powerful low in the Aleutians could be a good thing and there is one in the long range lol. Whats powering this? No idea. Possibly the deep cold air in Siberia. 240 on the Euro shows a nice HP near the pole that i would welcome to pay a visit to Central Tx.

Ntx, what dynamics are you seeing ANOTHER SSW event? Or is it what was left over from the last one? Already seeing warming in the 10MB layer again?

Also my low here in SL was 35.5F. Temps really crashed with the rain.

[TheProfessor]

The 12z parallel GFS appears wetter than the 6z, most of that precip comes after the cold leaves, but I'll take whatever I can get.

[Ralph's Weather]

The 12z parallel GFS appears wetter than the 6z, most of that precip comes after the cold leaves, but I'll take whatever I can get.

I was coming here to post that. The 12Z GFS is dry Sunday. Both are pretty much dry on Saturday also. I have a feeling that there will be some precip especially in E TX where there will be more moisture. I will be keeping a close eye on how this plays out. If we do get even light accumulations I would consider that a huge win for the PGFS. All the other models keep changing so much that they cannot be trusted.

[SouthernMet]

12z gfs keeps everything north of the red river..
12z gfs parallel consistent with up to 2" for metro.
Orangeblood you wanna chime in?

fwiw we're getting close to NAM guidance...

[orangeblood]

It's nice to be back in winter mode a little extra early this year....Sunday's system should not be taken lightly, with shortwaves moving along two separate streams this weekend, it's going to be very difficult for the models to pick up on the lifting mechanisms this far out. PWAT values seem efficient enough, cold air is in place, all we need is sufficient lift and there's decent chance of snow across the northern half of the state on Sunday. I'm not even paying attention to the old GFS at this point, I think you have to lean towards to higher resolution, smaller scale upgraded version at this point, don't you ?

[Ralph's Weather]

I'm not even paying attention to the old GFS at this point, I think you have to lean towards to higher resolution, smaller scale upgraded version at this point, don't you ?

I agree, I see nothing that gives me a reason to lean GFS, even the Euro is not consistent. We are almost in the range of the shorter term models that do a good job with small scale features.

[srainhoutx]

I see no significant changes to the earlier thinking regarding the weekend into early next week via the 12Z suite of Global guidance. This unusual early Winter like pattern continues to offer well below normal temperatures for Mid November across a large portion of the Lower 48. Subtle nuances with the progressive upper air disturbances will be the 'devil in the details' regarding our sensible weather.

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1059 AM EST THU NOV 13 2014

VALID 12Z SUN NOV 16 2014 - 12Z THU NOV 20 2014

...COLD PATTERN WILL CONTINUE ACROSS THE LOWER 48...

...OVERVIEW...
THE UPPER-LEVEL RIDGE/TROUGH PATTERN OVER CANADA AND ALASKA WILL
SUSTAIN AND MAINTAIN THE NORTH AMERICAN ARCTIC AIRMASS THROUGH
THIS MEDIUM RANGE PERIOD. THE PERSISTENCE OF THE PATTERN SPREADS
THE MODIFIED-ARCTIC AIRMASS DEEP INTO SOUTHERN
STATES...FLORIDA...THE RIO GRANDE VALLEY AND SOUTHERN GREAT BASIN.
THE DE-AMPLIFICATION OF THE UPPER-LEVEL PATTERN ALONG THE WEST
COAST PRODUCES AN ACTIVE PACIFIC JET AND A GRADUAL EQUATORWARD
MIGRATION OF THE SENSIBLE WEATHER PATTERN INTO THE SOUTHWEST
QUARTER OF THE NATION FOR DAYS 6-7.

...UNCERTAINTY ASSESSMENT...
IT CANNOT BE OVERSTATED HOW IMPORTANT THE SUSTAINED PRESENCE OF
ARCTIC AIR AND THE REPLENISHMENT OF THE AIRMASS DURING THIS MEDIUM
RANGE PERIOD WILL BE---TO SETTING UP A WINTRY P-TYPE PATTERN ALONG
ITS OUTER FRINGES---IN REGIONS OF THE DEEP SOUTH AND GREAT
BASIN/LEE OF THE CASCADES.

IN THE WEST...THE UNCERTAINTY AND FORECAST CHALLENGE IS THE
ABILITY OF ORGANIZED ONSHORE FLOW---AT LOW LEVELS AND AT JET
LEVEL---TO SCOUR OUT THE DRY/COLD CONTINENTAL AIRMASS
DRAPE...EXPANDING OVER A GREATER SURFACE AREA OF THE WESTERN
STATES.

IN THE SOUTH...THE CHALLENGE WILL BE THE ABILITY OF THE JET-LEVEL
WINDS EMBEDDED WITHIN THE BASE OF THE EASTERN NORTH AMERICAN
TROUGH...TO PROMOTE LIFT AND ELEVATE THE PROSPECTS FOR A WINTER
P-TYPE REGIME FROM THE SOUTHERN PLAINS TO THE GULF COAST.

...MODEL PREFERENCES...
THE CANADIAN...ECMWF...GFS AND UKMET 13/00Z CYCLE AND THE
ECENS...GEFS...NAEFS REASONABLY DEPICT THE MASS FIELDS THROUGH DAY
5. THE SUBTLE DIFFERENCES BETWEEN DETERMINISTIC RUNS VERSUS THE
ENSEMBLE MEANS---FOCUS ON TIMING OF THE PRIMARY AND SECONDARY
MID-LEVEL WAVE ENERGY TRANSPORT---ALONG AN ACTIVE UPPER-LEVEL JET
AXIS. FOR THE DAY 5-7 TIME FRAME...A 50/30/20 BLEND OF THE 13/00Z
ECENS-NAEFS-GEFS RESPECTIVELY SHOULD YIELD GOOD RESULTS FOR THE
APPROXIMATE POSITION/ALIGNMENT OF THE POLAR JET (564DM HEIGHT
LINE) AND THE ARCTIC JET (522DM HEIGHT CONTOUR) ACROSS THE NORTH
AMERICAN CONTINENT.

EARLY IN THE PERIOD---THE 500MB TROUGH AXIS AND ACCELERATED
JET-LEVEL WINDS ADVANCING AHEAD OF THE TROUGH...MIGRATE EASTWARD
AND NORTHEASTWARD ACROSS THE EASTERN STATES---DOWNWIND OF THE
MISSISSIPPI VALLEY (ALONG 90W ON TUESDAY/DAY5). THE SURFACE
FEATURE/WAVE TRACKING FROM THE MS DELTA TO THE OUTER BANKS SHOULD
USHER IN THE 'NEW' ARCTIC BOUNDARY ACROSS THE GREAT LAKES AND INTO
THE SOUTHEAST...WITH PRECIPITATION WHISKING RAPIDLY INTO THE
WESTERN ATLANTIC BASIN BY DAY 5. THE DETAILS ASSOCIATED WITH THE
DETERMINISTIC 13/00Z ECMWF MIGHT PROVIDE THE BETTER "MIDDLE
GROUND" DETAILS WITH THE THE ENTIRE TROUGH AXIS CARVING OUT FROM
THE NORTHERN HIGH PLAINS TO THE LOWER MS VALLEY---VERSUS A
SLIGHTLY FASTER CANADIAN AND SLIGHTLY SLOWER GFS DETERMINISTIC
SOLUTION BEYOND DAY 5. IN PARTICULARLY...THE TIMING OF THE
EMBEDDED MID-LEVEL WAVE ENERGY IN COMBINATION WITH THE LOW-LEVEL
THERMAL PROFILES WILL BE CRITICAL TO THE SENSIBLE WEATHER IMPACTS
ACROSS KEY AREAS---INCLUDING THE GREAT LAKES (BIG LAKE-EFFECT
SNOWS)...THE FLORIDA PENINSULA/THE NORTHERN GULF OF MEXICO
(CONVECTION OVER OPEN WATERS MOVING ATOP A COLD AIRMASS) AND
EASTERN MONTANA/WYOMING/COLORADO AND NORTHEAST TEXAS (STREAKS OF
MID-LEVEL MOISTURE AND FRONTOGENESIS). NOT A PERFECT PROG...BUT
HELPFUL WITH THE VERY SUBTLE...BUT WINTRY P-TYPE DETAILS
ABOVE/WITHIN THE ARCTIC AIRMASS---AT THIS POINT IN TIME.

IN THE WEST...FLOW PATTERN ALOFT AND PRESENCE OF AN ACTIVE NORTH
CENTRAL PACIFIC JET UPWIND OF THE UPPER-LEVEL RIDGE ALONG WESTERN
CANADA'S HIGH TERRAIN CREATES A VERY CHALLENGING
'SPLIT-FLOW/NEGATIVE-TILT' CONFIGURATION THAT INITIALLY PRODUCES
THE THREAT OF OVER-RUNNING MOISTURE FOR
WASHINGTON...OREGON...IDAHO. THEN ITS MIGRATION SOUTHWARD DOWN THE
COAST...INTO CENTRAL-SOUTHERN CALIFORNIA...THE SIERRA AND
DOWNSTREAM INFLUENCES ACROSS NEVADA CREATES SOME TIMING
DIFFERENCES. SOMETHING MORE---DETERMINISTIC CANADIAN-ECMWF "LIKE"
WOULD BE RECOMMENDED TO BETTER HANDLE THE TRICKY OFFSHORE-ONSHORE
TRANSITION AT THE SURFACE AND ALOFT. THIS PRESUPPOSITION INCLUDES
THE SOUTHWARD TRAJECTORY AND MIGRATION OF A MODERATELY-INTENSE
MID-LEVEL SHORTWAVE ALONG THE CASCADE/SIERRA SPINE EARLY IN THE
PERIOD. ITS PRESENCE REINFORCING THE CONTINENTAL AIRMASS INTO DAY
4-5...AND DELAYING THE EASTWARD-ADVANCING PACIFIC TROUGH AND ITS
CHARACTERISTICS/CONFIGURATION---IE CUTOFF AND/OR OPEN-WAVE.

...SENSIBLE WEATHER HIGHLIGHTS...
A VERY PROLONGED PERIOD OF LOCAL LAKE-EFFECT SNOWFALL EVENTS WILL
PREVAIL AT VARIOUS TIMES ACROSS ALL 5 GREAT LAKES. WITH
SIGNIFICANT SNOWS ALREADY PRESENT...HARD TO IMAGINE HOW MUCH MORE
SNOWFALL IS POSSIBLE...PROLIFIC? NUMBERS ARE POSSIBLE. ANOMALOUS?
CERTAINLY. THE PERSISTENCE OF THE COLD AIR...EMBEDDED SHORTWAVE
ENERGY AND RELENTLESS CYCLONIC FLOW (THE SYNOPTIC-SCALE PARAMETERS
IN PLACE) THROUGHOUT THE ENTIRE DAY 4-7 PERIOD TO GIVE EACH LAKE
AND THEIR SHORELINES THE THREAT OF UNUSUALLY-HIGH AMOUNTS OF
ACCUMULATION. OBVIOUSLY...THE SHORT-TERM WIND DIRECTION WILL PLAY
A CRITICAL ROLE. THE VERY DRY AIRMASS WILL LIMIT THE PRECIPITATION
EFFICIENCY AND INTENSITY OF LAKE-EFFECT DOWNSTREAM---WITH FAVORED
WINDWARD SLOPES AND LOCAL OROGRAPHIC FEATURES PERPENDICULAR TO THE
FLOW...BEARING THE BRUNT OF THE LAKE-EFFECT PROCESS.

WELL-BELOW TEMPERATURES SHOULD CONTINUE FOR THE EASTERN HALF OF
THE NATION... RANGING FROM 10-25F BELOW AVERAGE FOR THE MIDWEST
AND PLAINS. THE MODIFIED...BUT STILL THE AIRMASS WILL PRODUCE VERY
UNCOMFORTABLE AND CHILLY MORNINGS FOR THE GULF COAST AND FLORIDA.

SECONDARY SURGE OF CANADIAN AIR---WEST OF THE DIVIDE AND INTO THE
PACIFIC NORTHWEST/GREAT BASIN IN THE DAY 3-4 PERIOD 'SETS UP' AN
ENVIRONMENT CONDUCIVE FOR LOW SNOW LEVELS AND THE THREAT OF LIGHT
FREEZING DRIZZLE/RAIN. THE DEPTH OF AN ONSHORE FLOW ALONG THE WEST
COAST...AND ACTIVE 'SCOURING PROCESS' OF THE MODIFIED-ARCTIC
AIRMASS IN PLACE...WILL BE A LOCALLY-SENSITIVE SENSIBLE WEATHER
FEATURE THROUGH DAY 6.

VOJTESAK

[TheProfessor]

I didn't look at weather maps as much back then, but does the set up for Sunday look like what happened during the second part of the precip that occurred during the super bowl storm? I remember FWD thinking it would be too dry for snow that following Friday then they issued low pops, and then I ended up getting 6 inches of snow.

[SouthernMet]

I didn't look at weather maps as much back then, but does the set up for Sunday look like what happened during the second part of the precip that occurred during the super bowl storm? I remember FWD thinking it would be too dry for snow that following Friday then they issued low pops, and then I ended up getting 6 inches of snow.

Eh I don't think 6" is in play this time around, but I do think the models are struggling for whatever reason, like Orangeblood pointed out. IMO the gfs parallel is nailing it, not an abundance of moisture... But just enough lift, with the potential for mesoscale enhancement like the nws pointed out this morning.

[TheProfessor]

I didn't look at weather maps as much back then, but does the set up for Sunday look like what happened during the second part of the precip that occurred during the super bowl storm? I remember FWD thinking it would be too dry for snow that following Friday then they issued low pops, and then I ended up getting 6 inches of snow.

Eh I don't think 6" is in play this time around, but I do think the models are struggling for whatever reason, like Orangeblood pointed out. IMO the gfs parallel is nailing it, not an abundance of moisture... But just enough lift, with the potential for mesoscale enhancement like the nws pointed out this morning.

Well I didn't mean we'd get 6 inches, it was just an example of FWD and models having a struggle on how strong a short wave was.