December-Wet/Stormy New Years Eve Ahead

[unome]

it was picture-perfect grilling weather today, hope everyone in the way of bad weather tomorrow stays safe !

[srainhoutx]

The warm front has begun retreating N across the Texas Coast and the approaching short wave is nearing ABQ. The latest ensembles update from HPC Forecaster Kocin suggest a bit more southern track of the low pressure system and cyclogenesis should begin in earnest overnight into tomorrow morning across the Permian Basin (N Central TX) and wrap up into one heck of a Christmas Storm. Concern grows in the warm sector as a surface low develops along the warm front near or just NW of Austin/San Antonio and heads ENE. Further E in Louisiana/Mississippi/Alabama, the severe parameters are very concerning and certainly lend credibility to the Slight Risk across E TX/W LA tonight into tomorrow and the Moderate Risk. In the cold sector, 6-10 inches of snow with possible higher amounts are likely from Oklahoma City to Tulsa, Fort Smith/Fayetteville Arkansas area with lesser amounts along the Red River Valley down to Dallas/Ft Worth/Shreveport/Little Rock. Blizzard conditions are likely with up to a foot of snow across portions of Western Kentucky/Southern Illinois/SW Indiana. Stay safe and Merry Christmas KHOU Weather Community!

[Katdaddy]

Active weather day ahead for Christmas 2012 across SE TX. Tornado potential along and ahead of the N moving warm front from I-10 into the N CWA. Strong cold front approaches from the W with a concern for the warm sector. Hoping the cap is strong enough to limit development S and W of the metro area in the warm sector however should it break tornadic storms may occur. This will all move rapidly E into LA. Very concerned for a major event from LA into AL. On a positive note.....have a very Merry Christmas everyone!

[sambucol]

NAM forecast sounding for 6 am tomorrow, a tiny (about 400 meters) inversion, or probably very near the warm front.

What does this mean for us in the Houston area?

[unome]

we're already 3 degrees cooler than our forecast low for tonight

[Andrew]

The smaller the inversion, the easier it will be to break/ get around and not affect severe weather as much. If the inversion gets larger then it will limit the severe weather.

[srainhoutx]

Interesting discussion from NWS Dallas/Ft Worth this evening. One of the things I noticed this afternoon was the short wave was in fact a bit further S in New Mexico ~vs~ SE Colorado that the models had been suggesting. This could have rather significant implications in both the cold and warm sector and the severe threat expected. Stay Tuned!

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
912 PM CST MON DEC 24 2012

.UPDATE...
WE HAVE ANALYZED THE 00Z UPPER AIR DATA AND HAVE WATCHED THE
SURFACE OBS CLOSELY FOR SIGNS OF ANY DISCREPANCIES BETWEEN THEM
AND THE MODEL DATA. THE BIG THING THAT STANDS OUT ARE THAT THE
SURFACE LOW IN NORTHEAST NEW MEXICO AT 6PM WAS ABOUT 80 MILES
FARTHER SOUTH THAN ALL OF THE MODELS HAD FORECAST 24 HOURS AGO.
WHEN DEALING WITH A SWINGING/DIGGING UPPER LEVEL SYSTEM...THE
SURFACE PRESSURE PATTERN AND PRESSURE TENDENCIES OFFER ENORMOUS
CLUES ON THE FUTURE TRACK OF A POTENTIAL VORTICITY ANOMALY BEFORE
IT CLOSES OFF TO BECOME A FULL FLEDGED UPPER LOW. THE 3PM AND 6PM
SURFACE ANALYSIS SHOWED A LARGE REGION OF PRESSURE FALLS ACROSS
NEW MEXICO AND WEST TEXAS IN ADVANCE OF THE SYSTEM. GIVEN THE
ORIENTATION OF THE PRESSURE FALLS AND LOCATION OF THE SURFACE
LOW...IT CAN BE DETERMINED WITHOUT EVEN LOOKING AT A FORECAST
MODEL THAT THE UPPER LOW HAS NOT FINISHED DIGGING SOUTH. THE BIG
QUESTION IS HOW FAR SOUTH WILL THE UPPER LOW MAKE IT BEFORE IT
BEGINS TO SWING BACK TO THE NORTHEAST. AT THIS HOUR PRESSURE FALLS
CONTINUE IN THE REGION FROM LUBBOCK TO MIDLAND...WITH ANOTHER
PRESSURE FALL AREA DEVELOPING IN SOUTHEAST TEXAS. EXTRAPOLATING
SUGGESTS THE UPPER LOW WILL TRACK JUST SOUTH OF LUBBOCK BY SUNRISE
AND TO NEAR WACO BY SUNSET. AS THE LOW APPROACHES WACO...A WARM
FRONT WILL BE ORGANIZING OUT OF THE WEAK STATIONARY FRONT
CURRENTLY ANALYZED FROM SAN ANTONIO TO HOUSTON. BAROCLINIC QG
THEORY SUGGESTS THAT ONCE LOW LEVEL WARM ADVECTION BEGINS IN
EARNEST ACROSS SOUTHEAST TEXAS BY MORNING...IT WILL INDUCE HEIGHT
RISES TO THE SOUTHEAST OF OUR UPPER LOW WHICH WILL CAUSE THE LOW
TO CLOSE OFF AND FINISH DIGGING SOUTH...AND START ITS GRADUAL
TURN TO THE NORTHEAST. TOMORROW EVENING I WOULD EXPECT THE LOW TO
TRACK FROM NEAR WACO TO NEAR SHREVEPORT. IN SUMMARY THE USUAL
MEDIUM RANGE MODELS APPEAR TO BE A LITTLE TOO FAR NORTH WITH THE
TRACK OF THE UPPER LOW. OUR EXPECTATIONS FOR THE TRACK OF THE LOW
ALIGN WELL WITH THE RAP FORECAST WHICH IS TO THE SOUTH OF ALL
OTHER MODELS...SO WE WILL USE THE RAP HEAVILY.

OUR FORECAST HAS BEEN ON THE SOUTHERLY SIDE AND SNOWIER SIDE OF
THE MODEL GUIDANCE. SO ALTHOUGH WE ARE SEEING AN EVEN MORE
SOUTHERLY TRACK COME TO FRUITION...THIS DOES NOT NECESSARILY
MEAN THE FORECAST SNOW AMOUNTS NEED TO BE AMENDED MUCH. THIS IS IN
PART DUE TO THE DIFFICULTY IN GETTING THE COLDER/SUBFREEZING AIR
FARTHER SOUTH BEFORE THE PRECIPITATION ENDS. THE EXCEPTION IS THE
NORTHWEST ZONES WHERE THE MORE SOUTHERLY TRACK SUGGESTS MORE
PRECIP WILL FALL IN SUBFREEZING AIR. DUE TO THE TERRAIN EFFECTS
HERE...COLD AIR HAS AN EASY TIME GETTING INTO OUR NORTHWEST ZONES
WHEN WE HAVE A NORTH/NORTHEAST SURFACE WIND. HAVE EXPANDED THE
SNOW ADVISORY TO INCLUDE YOUNG/JACK/WISE COUNTIES...AND HAVE
INCREASED SNOW TOTALS TO THE 2-4 INCH RANGE FROM BOWIE TO SHERMAN.

THE NORTHEAST ZONES LIKELY WONT SWITCH TO SNOW UNTIL LATE
AFTERNOON...AS COLD AIR WILL HAVE TROUBLE MOVING IN AT THE SURFACE
DUE TO THE LEE SHADOW WARMING EFFECT OF THE OZARK PLATEAU. MOST OF
THE SNOW THAT OCCURS THERE WILL BE AFTER 6 PM AND WILL BE HIGHLY
DEPENDENT ON WHETHER MESOSCALE BANDING CAN SET UP IN THE WAKE OF
THE UPPER LOW. THE NEW NAM HAS FINALLY FORECAST SOME SIGNIFICANT
BANDING TO OCCUR...THUS WILL LEAVE THE ADVISORY ALONE IN THIS
AREA...BUT CONFIDENCE IS A LITTLE LOWER IN THE NORTHEAST ZONES FOR
2+ INCHES OF SNOW.

FARTHER TO THE SOUTH OF THE ADVISORY...FOR THE I-20 CORRIDOR AND
INCLUDING THE METROPLEX...THERE IS NOW HIGH CONFIDENCE THAT SNOW
WILL OCCUR. HOWEVER ALL INDICATIONS ARE THAT IT WILL STILL BE A
BRIEF 1-3 HOUR EVENT WITH NOT ENOUGH TIME TO GET ACCUMULATIONS
OVER AN INCH. IT MUST BE STRESSED THAT WITH TEMPERATURES FALLING
INTO THE 20S BY SUNSET...ANY APPRECIABLE MOISTURE REMAINING ON
BRIDGES...OVERPASSES AND EVEN SURFACE STREETS WILL LIKELY RE-
FREEZE INTO BLACK ICE. ALTHOUGH WE ARE USING 1+ INCH AS CRITERIA
FOR THE COUNTIES IN THE WINTER WEATHER ADVISORY AREA...WE MAY
EXPAND THE ADVISORY SOUTH INTO THE METROPLEX OVERNIGHT DUE SOLELY
TO TRAVEL IMPACTS.

FINALLY CONCERNING THE SEVERE WEATHER THREAT. WITH A MORE SOUTHERLY
TRACK OF THE UPPER LOW...THIS MEANS THERE IS LESS OF A CHANCE OF THE
WARM FRONT MAKING IT INTO THE SOUTHEAST CWA TONIGHT AS IT WILL
LIKELY STAY SOUTHEAST OF THE AREA. ELEVATED THUNDERSTORMS ARE STILL
EXPECTED TO RAPIDLY INCREASE IN COVERAGE AFTER 3 AM...WITH ELEVATED
INSTABILITY HIGH ENOUGH FOR A FEW SEVERE HAIL STORMS SOUTH OF I-20.
HAVE TONED DOWN THE DAMAGING WIND AND TORNADO THREAT FROM OUR
PRODUCTS...BUT WE WILL CONTINUE TO ADVERTISE HAIL STORMS POSSIBLE
LATE TONIGHT AND EARLY TOMORROW MORNING.

[Andrew]

Want to see an impressive Sounding? Look at the GFS sounding. While Severe weather to the east of here looks impressive I am concerned about the weather closer to here:

[srainhoutx]

The warm front is retreating N from the Coastal Counties at this hour...

[rnmm]

Want to see an impressive Sounding? Look at the GFS sounding. While Severe weather to the east of here looks impressive I am concerned about the weather closer to here:

Can someone decipher this for me???

[txsnowmaker]

Want to see an impressive Sounding? Look at the GFS sounding. While Severe weather to the east of here looks impressive I am concerned about the weather closer to here:

Can someone decipher this for me???

I'd like to second that request! I notice that the text under the graphic shows a 91.4% supercell potential, but not sure what time/location that applies to...

[Andrew]

Want to see an impressive Sounding? Look at the GFS sounding. While Severe weather to the east of here looks impressive I am concerned about the weather closer to here:

Can someone decipher this for me???

I'd like to second that request! I notice that the text under the graphic shows a 91.4% supercell potential, but not sure what time/location that applies to...

The sounding is for 12 hours past the 00z run which should be around the morning time period. What looks so impressive about this sounding is the upper 60 to mid 70kt shear that is presented should allow for super-cell storms to really erupt. Also SWEAT index which is a makeup of multiple criterion such as wind speed in different levels of the atmosphere and dew-points is really high. Anything over 400 is impressive and we are at 549. Also CAPE (energy in the atmosphere) is over 2k (J/KG) which really shows how much energy is in the air. On top of that we have a low level of free convection and EHI (which is a makeup of CAPE and Helicity) is at 3.6 which is pretty good. Only thing that COULD be a hiccup is the small inversion of temperatures between 850mb and 750mb but with the west to east orientation of the jet this shouldn't be too big of an issue. Overall this sounding shows a really impressive situation that could cause some really strong storms in the morning. Keep an eye out everyone and stay safe.

[Ptarmigan]

This could be an interesting Christmas. Ho! Ho! Ho!

[srainhoutx]

NCEP Operational Status Message
Tue Dec 25 03:58:48 2012 GMT
NOUS42 KWNO 250358
ADMNFD
SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE
NWS NCEP CENTRAL OPERATIONS COLLEGE PARK MD
0350Z TUE DEC 25 2012
A REGIONAL CRITICAL WEATHER DAY...CWD...HAS BEEN DECLARED
STARTING AT 1200Z TUE DEC 25 2012 AND EXTENDING THROUGH 1200Z FRI
DEC 28 2012.
THE FOLLOWING NWS REGIONS ARE IMPACTED BY THIS CWD...
SOUTHERN REGION UNTIL 12Z WEDNESDAY
EASTERN REGION UNTIL 12Z FRIDAY
NCEP/NWSTG AND THE NCF ARE ALSO PARTICIPATING IN THIS CWD TO
ENSURE A RELIABLE FLOW OF WEATHER DATA. ALL SCHEDULED
SOFTWARE/HARDWARE/NETWORK CHANGES FOR THE IMPACTED OFFICES WILL
BE POSTPONED UNTIL THE CWD HAS ENDED. ANY EMERGENCY CHANGES WILL
BE EVALUATED AND APPROVED BY THE LOCAL/REGIONAL MANAGEMENT
OFFICIALS. NWS OFFICES SHOULD CONTACT THEIR REGIONAL OFFICES FOR
FURTHER QUESTIONS ABOUT THIS CWD.
HANDEL/SDM/NCO/NCEP

[dac]

Merry Christmas all! Heading to Albuquerque from Tomball tomorrow morning - route is through Lubbock and Clovis. Any advice on when best to leave and what we might run into? Appreciate all the posts thus far as always!

[srainhoutx]

Merry Christmas all! Heading to Albuquerque from Tomball tomorrow morning - route is through Lubbock and Clovis. Any advice on when best to leave and what we might run into? Appreciate all the posts thus far as always!

I'd head W before trekking N to Lubbock. Things could get a bit dicey across N TX. I'll be head to ABQ as well in two weeks...but that will be a flight ~vs~ driving. Safe travels!

[srainhoutx]

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1200 AM CST TUE DEC 25 2012

VALID 251200Z - 261200Z

...THERE IS A MDT RISK OF SVR TSTMS ACROSS SOUTHEAST TX AND PORTIONS
OF LA/MS/AL/FL PANHANDLE...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE GULF COAST/SOUTHEAST
STATES...

...A DANGEROUS CHRISTMAS DAY/NIGHT SEVERE WEATHER EPISODE IS LIKELY
TO UNFOLD...INCLUDING THE POTENTIAL FOR STRONG TORNADOES AND
WIDESPREAD DAMAGING WINDS...ACROSS PORTIONS OF THE GULF COAST REGION
AND LOWER MS RIVER VALLEY...

...SYNOPSIS...
A PROGRESSIVE LARGE SCALE FLOW PATTERN WILL PREVAIL OVER THE CONUS
DURING THE PERIOD. THE PRIMARY SYSTEM OF FOCUS WITH RESPECT TO DEEP
CONVECTION WILL BE A VIGOROUS SHORTWAVE TROUGH /AND ASSOCIATED
STRONG UPPER JET STREAK/ AS IT SPREADS EASTWARD...AMPLIFIES...AND
THEN BECOMES INCREASINGLY CLOSED/NEGATIVELY TILTED TONIGHT AS IT
ADVANCES FROM THE SOUTHERN PLAINS TO THE LOWER MS VALLEY/TN VALLEY.

...GULF COAST REGION/LOWER MS VALLEY TO SOUTHEAST STATES...
GIVEN THE LARGE SCALE SCENARIO AS PREVIOUSLY DESCRIBED...A SURFACE
LOW IS EXPECTED TO STEADILY DEEPEN AS IT SPREADS NORTHEASTWARD FROM
SOUTHEAST TX THIS MORNING TO THE TN VALLEY TONIGHT. AS THIS
OCCURS...AN INCREASINGLY MOIST LOW-LEVEL AIRMASS WILL DEVELOP
NORTHWARD IN TANDEM WITH A WEST-EAST ORIENTED WARM FRONT...WITH
LOWER 60S DEWPOINTS /AND SOME MIDDLE 60S F NEAR THE COAST/ BECOMING
INCREASINGLY PREVALENT WITHIN THE WARM SECTOR.

INITIALLY...STRONG/POTENTIALLY SEVERE TSTMS ARE EXPECTED TO BE
ONGOING THIS MORNING...ESPECIALLY ACROSS SOUTHEAST TX INTO LA. THIS
INCLUDES THE POSSIBILITY OF ELEVATED SUPERCELLS NORTH OF THE WARM
FRONT /MAINLY CAPABLE OF HAIL/...ALONG WITH AN INCREASING SURFACE
BASED SEVERE THREAT NEAR/SOUTH OF THE WARM FRONT THIS MORNING ACROSS
THE UPPER TX COAST/SOUTHERN LA. WITHIN AN INCREASINGLY MOIST AND
HIGHLY SHEARED ENVIRONMENT...THIS INCLUDES THE POSSIBILITY OF AN
EARLY DAY TORNADO/WIND DAMAGE THREAT THIS MORNING/EARLY AFTERNOON
ACROSS SOUTHEAST TX INTO SOUTHERN LA.

WITH TIME...THE AIRMASS WILL FURTHER DESTABILIZE INTO THIS AFTERNOON
ESPECIALLY ACROSS CENTRAL/SOUTHERN LA AND SOUTHERN PORTIONS OF
MS/AL...WITH 1000+ J/KG MLCAPE FOR AREAS WITHIN 150-200 MILES OF THE
GULF COAST. LESSER...AND A BIT MORE UNCERTAIN...DESTABILIZATION IS
EXPECTED CLOSER TO THE EAST-NORTHEASTWARD SURFACE LOW LATER
TODAY/TONIGHT...LARGELY OWING TO PERSISTENT PRECIPITATION NEAR/NORTH
OF THE WARM FRONT AND A LESSER INFLUX OF LOW-LEVEL MOISTURE.

REGARDLESS...THIS DESTABILIZATION COUPLED WITH AN INCREASINGLY
STRONG DEEP LAYER WIND FIELD...WITH 70-100 KT AT 500 MB AND
110+ KT AT 250 MB...WILL RESULT IN DEEP LAYER SHEAR SUPPORTIVE OF
ROTATING UPDRAFTS/SUPERCELLS. ACCENTUATED BY THE DEEPENING PHASE OF
THE CYCLONE...EVENTUAL QLCS DEVELOPMENT SEEMS LIKELY TO OCCUR THIS
AFTERNOON INTO TONIGHT NEAR/AHEAD OF THE EASTWARD-ADVANCING COLD
FRONT...ALTHOUGH DISCRETE SUPERCELLS WILL REMAIN POSSIBLE WITHIN THE
WARM SECTOR AND NEAR/IMMEDIATELY AHEAD OF THE EVOLVING QLCS...WHICH
SEEMS LIKELY TO CROSS LA AND THE SOUTHERN HALVES OF MS/AL THROUGH
TONIGHT. POTENTIALLY WIDESPREAD DAMAGING WINDS WILL BE POSSIBLE WITH
SUSTAINED BOWING SEGMENTS. FURTHERMORE...A FEW STRONG/POTENTIALLY
LONG-LIVED TORNADOES WILL ALSO BE POSSIBLE WITH DISCRETE SUPERCELLS
AND/OR EVENTUAL EMBEDDED MESO-VORTICES LATER THIS
AFTERNOON/TONIGHT...ESPECIALLY GIVEN 200-500 M2/S2 0-1 KM SRH
COINCIDENT WITH A 50-70 KT LOW LEVEL JET LATE THIS
AFTERNOON/TONIGHT.

WHILE THE OVERALL SYSTEM STRENGTHENS...INSTABILITY WILL WANE LATE IN
THE PERIOD. EVEN SO...A SEVERE THREAT MAY REACH AS FAR EAST AS PARTS
OF AL...SOUTHEAST TN...AND WESTERN GA LATER TONIGHT...WITH SOME
POTENTIAL FOR AREAS INCLUDING COASTAL SC BY THE EARLY MORNING HOURS
OF WEDNESDAY.

..GUYER/SMITH.. 12/25/2012

[Ptarmigan]

Merry Christmas to everyone! The Doppler radar is really lighting up like a Christmas tree. I would not be surprised to see the radar really lit up later this morning. It could be a rough one for Santa Claus. I checked Weather Underground with their Doppler radar with lightning detection and no lighting with those storms. That could change later on.

[srainhoutx]

Merry Christmas all! Heading to Albuquerque from Tomball tomorrow morning - route is through Lubbock and Clovis. Any advice on when best to leave and what we might run into? Appreciate all the posts thus far as always!

I'd head W before trekking N to Lubbock. Things could get a bit dicey across N TX. I'll be head to ABQ as well in two weeks...but that will be a flight ~vs~ driving. Safe travels!

dac, Lubbock considering updating to a Winter Storm Warning with the latest trends further S of the low track. Just an FYI.

[dac]

Yikes! Just saw that! Will reasses in the morning! Thank you very much!