November: Cool & Dry To End The Month

[srainhoutx]

MESOSCALE DISCUSSION 2349
NWS STORM PREDICTION CENTER NORMAN OK
0346 PM CST MON NOV 21 2011

AREAS AFFECTED...CNTRL INTO NERN TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 212146Z - 212345Z

THE THREAT FOR SVR THUNDERSTORMS COULD INCREASE DURING THE NEXT FEW
HOURS FROM CNTRL INTO NERN TX...AND THIS AREA WILL BE MONITORED FOR
THE POSSIBLE ISSUANCE OF A WW.

VISIBLE SATELLITE IMAGERY AND SFC OBS INDICATE A STRONG FRONT SLOWLY
RETREATING NWD OVER PORTIONS OF CNTRL/ERN TX...WITH MLCAPE VALUES OF
1000-1500 J/KG SOUTH OF THE BOUNDARY. THIS IS OCCURRING AS
INCREASING MID-LEVEL HEIGHT FALLS AHEAD OF A PAIR OF APPROACHING
SHORTWAVE TROUGHS INDUCE SFC PRESSURE FALLS OF 3 TO 4 MB PER 2 HRS
NORTH OF THE BOUNDARY. LITTLE IN THE WAY OF CONVECTION HAS BEEN
NOTED NEAR OR SOUTH OF THE BOUNDARY THUS FAR...OWING TO WEAK
VELOCITY CONVERGENCE ALONG THE FRONT...WITH THE STRONGEST DEEP-LAYER
ASCENT AND ASSOCIATED CONVECTION FARTHER N ACROSS N-CNTRL TX NWD
INTO OK. HOWEVER...AS THE MID-LEVEL TROUGHS MAKE ADDITIONAL EWD
PROGRESS...THUNDERSTORMS COULD DEVELOP LATER THIS AFTERNOON.
EFFECTIVE BULK SHEAR MAGNITUDES OF 50-55 KT WILL CONDITIONALLY
PROMOTE A THREAT FOR SUPERCELLS...WITH SVR HAIL THE PRIMARY CONCERN.
HOWEVER...ANY STORMS THAT ARE ABLE TO INTERACT WITH THE FRONT AS IT
LIFTS NWD...OR EVOLVE WITHIN THE WARM SECTOR...WILL ALSO BE CAPABLE
OF PRODUCING DMGG WIND GUSTS...AND POSSIBLY A TORNADO.
HOWEVER...WEAKENING LOW-LEVEL SRH WITH SWD DISPLACEMENT FROM THE
BOUNDARY PER VWP DATA SUGGESTS THAT ANY TORNADO THREAT...ALBEIT
MINIMAL...WILL BE CONFINED TO A NARROW CORRIDOR ALONG THE SFC FRONT.
GIVEN THE UNCERTAINTY IN CONVECTIVE INITIATION/COVERAGE...THE NEED
FOR A WW IS UNCERTAIN. HOWEVER...TRENDS WILL CONTINUE TO BE
MONITORED FOR POTENTIAL WW ISSUANCE.

..COHEN.. 11/21/2011


ATTN...WFO...SHV...HGX...FWD...EWX...

[srainhoutx]

Morning e-mail from Jeff:

Cold front crossing SE TX this morning with ongoing showers and thunderstorms across the region.

At 600am a cold front extended from near Tyler to College Station to San Antonio moving ESE at 15-20mph. Numerous thunderstorms have developed along the boundary from Lufkin to Brenham. A secondary band of thunderstorms is rapidly developing over Wharton and Matagorda Counties and this band will be moving toward Fort Bend and Harris Counties shortly. While the air mass is unstable, frontal timing (early morning) and weak shear will support on a very marginal severe weather threat for the morning hours as the front crosses the area. Most severe modes will be isolated wind damage and this threat will be mainly north of I-10.

Faster frontal movement and rapid forward cell motion is helping to mitigate the heavy rainfall in this highly tropical air mass over the region. Could see a period of cell training along and just N of the US 59 corridor this morning for a few hours as radar shows this is where cells are developing ahead of the main line, but incoming front will shift this activity E/S in a few hours. Rainfall amounts will average .5-1.0 inch with a few isolated totals up to 1.5 inches especially north of I-10 and east of I-45. Front should be reaching the coast early this afternoon or several hours faster than what models were showing yesterday. Rain will end quickly from NW to SE post front with clearing skies by late afternoon.

Dry weather on tap for Wednesday and Thursday with weak high pressure in control before rapid changes Friday-Sunday. Lows in the 40’s and 50’s and highs in the 70’s both days under mostly sunny skies.

Next very strong storm system will begin to approach the area Friday with a rapid influx of moisture starting very late Thursday night. Deep moisture with PWS progged to rise again toward 1.8 inches by Friday afternoon will support the formation of showers and thunderstorms. Strong deep layer lift from the trough moves into the area late Friday night into Saturday with widespread thunderstorms expected. System does support some severe potential along with heavy rainfall, but as with the last several looks fast moving.

Strong high pressure will build southward behind this system with low pressure deepening over the lower MS valley Saturday and Sunday. Impressive pressure rising over TX will support very strong post frontal winds Saturday into Sunday with sustained speeds of 20-30mph and gust over 35-40mph. This system will also tap some cold air over the northern US and expect falling temperatures on Saturday under strong cold air advection regime (highs in the 70’s early falling into the 50’s during the afternoon). Cold high pressure will settle over the region Sunday evening with freezing temperatures possible in some areas Monday morning. Another strong front with modified arctic air appears possible just beyond this weekend (early next week) with even colder conditions and the threat of a more widespread freeze.

[srainhoutx]

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
744 AM CST TUE NOV 22 2011

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
NORTHWESTERN LIBERTY COUNTY IN SOUTHEAST TEXAS...
SOUTHERN POLK COUNTY IN SOUTHEAST TEXAS...

* UNTIL 815 AM CST

* AT 741 AM CST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS
OF 60 MPH. THIS STORM WAS LOCATED NEAR CLEVELAND...AND MOVING EAST
AT 35 MPH.

* LOCATIONS IN THE SEVERE THUNDERSTORM WARNING INCLUDE BUT ARE NOT
LIMITED TO TARKINGTON PRAIRIE AND ROMAYOR..

[srainhoutx]

For our neighbors to the E...

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE LAKE CHARLES LA
831 AM CST TUE NOV 22 2011

THE NATIONAL WEATHER SERVICE IN LAKE CHARLES HAS ISSUED A

* TORNADO WARNING FOR...
EASTERN VERNON PARISH IN WEST CENTRAL LOUISIANA...
THIS INCLUDES...SLAGLE...LEESVILLE...FORT POLK...

* UNTIL 900 AM CST

* AT 828 AM CST...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO NEAR FORT
POLK...MOVING NORTHEAST AT 45 MPH.

* THE TORNADO WILL BE NEAR...
SLAGLE BY 840 AM CST...
LACAMP BY 850 AM CST...

[txflagwaver]

Hope we at least get some rain this morning...

[redneckweather]

I think it's time for a DECEMBER weather thread. Will somone do us the honors?

[srainhoutx]

I think it's time for a DECEMBER weather thread. Will somone do us the honors?

I can think of no one better than you, redneckweather...

[srainhoutx]

There is still some timing issues regarding the Thanksgiving Weekend storm system, but the models are suggesting a squall line over night Friday into Saturday. The trends continue to suggest a strong front with modified Canadian air being pulled S into the Plains as the Upper Low closes off somewhere in the mid Mississippi River Valley. It does look like we will see very breezy conditions behind the front and Sunday night could bring freezing conditions to at least the I-10 corridor. We will see.

[srainhoutx]

The 12Z Euro suggests it will be rather chilly on Sunday...

HPC Final Update:

12Z GFS CONSISTENT WITH ITS IDEA OF A STRONG CLOSED/CUTOFF LOW
MID/LATE PERIOD. LATEST 12 CMC IS FASTER TAKING OUT THE MID LEVEL
TROF AND CLOSED LOW INTO THE UPPER OH VALLEY DAY 6 MON WHILE
AWAITING ANOTHER STRONG DIGGING TROF DAY 7 TUES AS DOES THE GFS.
12Z UKMET IS ALSO MORE PROGRESSIVE WITH FULL LATUITDE DEEP AND
SHARP TROF INTO THE APPLCHNS DAY 6. NOGAPS CONSISTENT WITH ITS MID
LEVEL CUTOFF
IN/OH DAY 7 TUES. EACH MODEL RUN UNTIL MUCH CLOSER IN WILL OFFER A
DIFFERENT LOCATION OF THE MID LEVEL CENTER AND DETAILS. SINCE THE
PRIOR HPC BLEND WAS MULTI MODELED SEE NO REASON TO CHANGE AT THIS
TIME FOR AFTN FINALS.

FAIR AGREEMENT OF THE NEXT PACIFIC TROF COMING INTO THE PAC
NORTHWEST AND NRN ROCKIES LATE SUN AND MON. ECMWF IS QUITE STRONG
WITH ANOTHER SHORTWAVE COMING INTO THE PACIFIC NORTHWEST BY TUES
WITH ITS ENS MEAN AND CMC MUCH MORE DAMPENED AND NON EXISTENT IN
THE GFS SOLUTION. THIS IS ALSO SUPRESSED BY THE HPC BLEND.

SRN STREAM SHORTWAVE WILL SPREAD RAIN ACROSS NWRN MEXICO INTO
NM/TX AND OK FRI WHILE NRN STREAM ENERGY WILL KEEP THE PACIFIC
NORTHWEST AND NRN ROCKIES WET. SHARPENING OF THE MID LEVEL TROF AS
PHASING OCCURS WILL BACK THE MID LEVEL FLOW AND ALLOW DEEP GULF
MOISTURE AND HVY PCPN TO SURGE NWD THRU EAST TX/OK/AR/MO AND UP
WELL NORTH INTO THE MS VALLEY SAT AND SUN. THIS WILL SPREAD
EASTWARD INTO THE APPLCHNS MON AND INTO THE MID ATLC COASTAL PLAIN
AND NORTHEAST BY TUES. COLD RAIN UNDER THE MID LEVEL CENTER IN THE
OH VALLEY/APPLCHNS WITH MID/LOWER LEVEL TEMPERATURES POTENTIALLY
COLD ENOUGH FOR HIGHER AND EVEN LOWER ELEV SNOW IN THE CENTRAL AND
SRN APPCHNS/UPPER OH VALLEY EARLY NEXT WEEK WITH SNOW POSSIBLE
ALONG THE WESTERN PORTION OF THE CIRCULATION IN THE MS VALLEY AND
PLAINS. HEAVY RAIN POTENTIAL EASTWARD ALONG THE SLOW MOVING
NEGATIVELY TILTED FRONT FROM THE SRN APPCHNS INTO PA. MDT TO
LOCALLY RAINS POSSIBLY UP ALONG THE ATLC SEABOARD AND INTO THE
PIEDMONT AND FOOTHILLS FROM GA INTO NEW ENGLAND MON INTO TUES.
LOCATION AND TRACK OF THE H500 MID LEVEL LOW ALONG WITH
ACCOMPANYING H850 COLD POOL MAY BECOME VERY CRITICAL ESPECIALLY
OVER HIGHER TERRAIN OF THE APPLCHNS.

[srainhoutx]

HGX hinting a very chilly Sunday around these parts:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
254 PM CST TUE NOV 22 2011

.DISCUSSION...
THE FRONT IS STILL WORKING ITS WAY TOWARD THE COAST AND SHOULD
CROSS THE COAST AROUND 21Z. MUCH COOLER AND DRIER AIR WILL WORK
INTO SOUTHEAST TEXAS OVERNIGHT. HIGH PRESSURE WILL SETTLE OVER
NORTH TEXAS ON WEDNESDAY AND PUSH EAST OF THE REGION ON THURSDAY.
CLEAR SKIES ARE EXPECTED ON WEDNESDAY BUT WITH A RETURN FLOW ON
THURSDAY...FEEL CLOUDS WILL BEGIN TO DEVELOP LATE THURSDAY
AFTERNOON OR MORE LIKELY THURSDAY NIGHT. WARM AIR ADVECTION AND A
RETURN OF MOISTURE WILL LEAD TO A SLIGHT CHANCE OF SHOWERS ON
FRIDAY AFTERNOON AND FRIDAY NIGHT. A STRONG UPPER LEVEL TROUGH
WILL MOVE TOWARD TEXAS FRIDAY NIGHT AND SATURDAY. THERE ARE STILL
SOME TIMING DIFFERENCES...BUT IT APPEARS THE TROUGH AND SURFACE
COLD FRONT WILL CROSS THE REGION ON SATURDAY. MOISTURE LEVELS WILL
AGAIN RISE TO AROUND 1.8 INCHES ON SATURDAY. UPPER LEVEL DIVERGENCE
LOOKS IMPRESSIVE WITH A NICE SPLIT IN THE JET. SOUTHEAST TEXAS
WILL ALSO LIE IN A STRONG RIGHT REAR QUAD. WILL MAINTAIN HIGH END
CHANCE POPS.

STRONG COLD AIR ADVECTION WILL PREVAIL BEHIND THE FRONT AND
SUNDAY LOOKS TO BE THE COLDEST DAY OF THE FALL. 850 MB TEMPS ARE
PROGGED TO FALL TO BETWEEN -3 AND -5 DEGREES. THINK A FEW
LOCATIONS WILL STRUGGLE TO REACH 50 DEGREES ON SUNDAY. UNDERCUT
MEX GUIDANCE FOR BOTH SUN/MON.

[srainhoutx]

The guidance continues to struggle beyond 48 hours. The NAM and Euro have slowed the front down a bit for Saturday. While showers and storms still look likely Saturday morning into mid day, the rain amounts seem to not be as much as earlier indicated. The big news is what happens after the front/trough passes. The Euro has switched back to a cut off solution with a mid/upper low just to our E. The northern stream across the Great Lake/Upper Mid West is very progressive, so we may see this cut off solution in the southern flow play out. The disturbance is still offshore of California this morning so there will likely been further changes in the wacky guidance in this pattern. It still looks very breezy and cold behind the front for Saturday night into Sunday. If the cut off low that the Euro suggests happens, those cold and breezy conditions could extend into Monday. We will see...

[srainhoutx]

It looks like shower and storms will be the theme for early Saturday morning into the afternoon hours as a strong trough/cold front sweep across the region. We'll need to keep and eye to our W Friday night as squall line may develop over Central Texas just ahead of the front. There still remains some model mayhem regarding the developing Upper Low and just where this feature forms. Regardless, very breezy and cool with highs in the 50's behind the front with and lows in the 30's can be expected Moday morning for inland areas. We see what guidance offers today concerning any severe weather threat for Saturday.

[srainhoutx]

The 12Z Canadian is back to a SW LA cutoff solution. As noted by the HPC this morning, the guidance is throwing major curveballs from run to run. We may not know exactly how this all plays out until the U/L actually cuts off. What a forecasting challenge ahead...

[srainhoutx]

SPC Update:

...SERN TX...LA...SRN MS AND AL...
A LINE OF SHOWERS AND THUNDERSTORMS IS EXPECTED TO BE ONGOING ALONG
THE COLD FRONT FROM ERN TX INTO THE ARKLATEX EARLY SATURDAY.
FORECAST SOUNDINGS INDICATE THAT ALTHOUGH BOUNDARY LAYER DEWPOINTS
WILL RISE INTO THE LOWER TO MID 60S F...LAPSE RATES ALOFT WILL
GENERALLY BE POOR...WITH WEAK LI VALUES AND MUCAPE ON THE ORDER OF
250-500 J/KG. HOWEVER...GIVEN STRONG AND PERSISTENT FORCING...AS
WELL AS MODESTLY STRONG DEEP LAYER WIND SHEAR PROFILES...A FEW
BOWING STRUCTURES WITH ATTENDANT WIND THREAT CANNOT BE RULED OUT.

[srainhoutx]

The 12Z Euro has trended a bit W and also cuts off the upper low over Louisiana which is somewhat similar to the Canadian/Ukmet solution). It appears that the guidance is trending to slow the progression of the trough/Upper Low which would tend to mean breezy and cooler temps extending into Monday. We will see...

[srainhoutx]

The 12Z Euro has trended a bit W and also cuts off the upper low over Louisiana which is somewhat similar to the Canadian/Ukmet solution). It appears that the guidance is trending to slow the progression of the trough/Upper Low which would tend to mean breezy and cooler temps extending into Monday. We will see...

Check the local area Canadian Global 4 panel maps on the PSU e-Wall. I'm fairly certain this time of the year surface temps won't support anything significant, but extreme East Texas and Louisiana would seem to have favorable thicknesses and moisture to mix in some snow IF the Canadian verified.

Stranger things have happened with these cold core upper lows. My hunch would be some sleet potential in the areas you mentioned, but that is still somewhat in doubt due to just exactly where this disturbance decides to close off. That said and if the trends continue, our neighbors to the NE (Arkansas/NE TX/NW LA) could see a flake or two mixing in. What does raise an eyebrow is the fact that guidance may yet be too progressive (faster moving) than what actually occurs. Regardless, it is going to feel much colder with the winds gusting in our area.

[Belmer]

I sure am liking what I'm seeing for the long range computer models NEXT week. Things sure do look interesting to say the least. Though, this is getting into winter season here in the Lone Star State, and things love to change all the time. Can't get anything down to good accuracy till about 3 days out. I mean, we can't even get a definite forecast for tomorrow, Sunday and into Monday. But at least they have some winter precipitation into next week around our area.
It's that time of the year again everyone, here soon the board will be ramped up.
Meanwhile, hope everyone had a wonderful Thanksgiving and let's see what these next few days will bring us before we really get going into next week.

[srainhoutx]

The 12Z Euro Ensembles are latching on to a slower/deeper cutoff low and mighty close to E TX/LA...for what it's worth...also the 18Z NAM has come in slower and now suggests a cutoff low to our E with colder 850mb temps for Central/SE TX Sunday into Monday...

[Ptarmigan]

The 12Z Euro Ensembles are latching on to a slower/deeper cutoff low and mighty close to E TX/LA...for what it's worth...also the 18Z NAM has come in slower and now suggests a cutoff low to our E with colder 850mb temps for Central/SE TX Sunday into Monday...

Let's hope it gives us rain. Cutoff lows usually give a lot of rain for us.

[srainhoutx]

The 18Z GFS now suggesting the cutoff low will develop near the ArkLaTx region...