Winter Storm and Winter Weather in Texas, December 29 to 30, 2009

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LUBBOCK TX
532 AM CST TUE DEC 29 2009

.AVIATION...
BIGGEST QUESTION REMAINS ONSET OF WINTRY PRECIPITATION. ALREADY
SEEING REPORTS OF SNOW AT KMAF SOUTH OF THE TERMINALS AND THIS
SHOULD SPREAD NORTHWARD THROUGH THE MORNING. START OF SNOW AT KLBB
IS ANTICIPATED TO BE 15Z WITH HEAVIEST SNOWFALL FROM AROUND 17Z
THROUGH 22Z WHEN MUCH OF THE SNOW SHOULD FALL. ANTICIPATE AMOUNTS
FROM 1 TO 3 INCHES. GOOD NEWS IS THAT WIND SHOULD REMAIN LIGHT AND
VARIABLE FOR MUCH OF THE EVENT. SNOW SHOULD THEN SPREAD INTO THE
KCDS TERMINAL LATER THIS AFTERNOON AND TAPER OFF BY LATE TONIGHT.
EXPECT FLURRIES THROUGH LATE EVENING AT KLBB BEHIND THE MAIN AREA
OF SNOW. IFR CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE
SNOW...ALTHOUGH PERIODS OF LIFR COULD DEVELOP IN THE HEAVIER SNOW
BANDS. CONDITIONS WILL THEN IMPROVE TOWARDS SUNRISE WEDNESDAY
ACROSS BOTH TERMINALS.

JORDAN

&&

.PREV DISCUSSION... /ISSUED 410 AM CST TUE DEC 29 2009/

SHORT TERM...
NEXT WINTER STORM SYSTEM CONTINUES TO APPROACH THE AREA BUT APPEARS
TO BE TAKING A BIT MORE NORTHERN/WESTERN TRACK THAN PREVIOUSLY
THOUGHT.

LATEST WV IMAGERY SHOWS THE BASE OF THE TROF JUST PASSING WEST OF EL
PASO AND CONTINUING ON A NORTHEASTERLY TRACK.  STILL NOT SURE THAT
MODELS HAVE A GOOD HANDLE ON THE SITUATION AS BASE OF THE TROF WAS
OVER NORTHERN MEXICO AT 00Z AND THE NEAREST UPA SITES WERE QUITE A
WAYS NORTH OF OF THIS FEATURE.  THIS LIKELY HAS CAUSED SOME OF THE
DIFFERENCES IN THE MODELS WITH THE SPEED AND TIMING OF THE TROF. GFS
HAS THE BASE OF THE TROF MOVING JUST NORTH OF THE FCST AREA THROUGH
THE AFTERNOON...THE NAM CARRIES THE TROF OVER NERN NM...AND THE
ECMWF HAS A SLIGHTLY DEEPER TROF BUT FOLLOWS SIMILAR TIMING TO THE
ECMWF.

REGARDLESS...OVERALL PATTERN STILL LOOKS FAVORABLE FOR MEASURABLE
SNOWFALL ACROSS THE SOUTH PLAINS AND ROLLING PLAINS ALTHOUGH TIMING
MAY BE A BIT SLOWER THAN PREVIOUSLY THOUGHT.  TIME SERIES...CROSS
SECTIONS...AND SOUNDINGS FROM MODEL DATA AND BUFKIT SHOW THAT
TEMPERATURE PROFILES ALL DROP BELOW FREEZING MID-MORNING AS THE
COLUMN STARTS TO MOISTEN FROM THE TOP DOWN.  WEAK TO MODERATE LIFT
AS SHOWN IN OMEGA FIELDS ALSO HELPS TO COOL THE COLUMN.  AS THE MAIN
STORM SYSTEM PUSHES JUST WEST OR OVER THE REGION...SNOWFALL SHOULD
START BY MID MORNING ACROSS THE SOUTHWEST AND SPREAD NORTHEASTWARD
THROUGH THE DAY.  MODELS DEPICT THAT THE HEAVIEST SNOWFALL WILL FALL
FROM LATE MORNING THROUGH MIDDAY ACROSS THE SOUTH PLAINS...ROUGHLY
FROM NOON THROUGH 6 PM.  BIGGEST LIMITING FACTOR ON SNOWFALL IS THAT
STRONGEST LIFT APPEARS TO TAKE PLACE BELOW THE DENDRITIC SNOW GROWTH
ZONE.  MODERATE SNOWFALL MAY STILL BE POSSIBLE BUT DO NOT EXPECT
WIDESPREAD HEAVY SNOWFALL FOR EXTENDED PERIOD OF TIME KEEPING
AMOUNTS IN ADVISORY CRITERIA RANGE.

OPTED TO CONTINUE ADVISORY AS IS WITH AMOUNTS GENERALLY AROUND 2
INCHES ALTHOUGH IT MAY NEED TO BE EXTENDED ACROSS THE NORTHERN
ROLLING PLAINS THROUGH 06Z SHOULD THE TROF KICK OUT SLOWER AND
SNOWFALL LINGERS.  HEAVIEST SNOWFALL WAS PLACED ACROSS THE SOUTHERN
SOUTH PLAINS AND SOUTHERN ROLLING PLAINS WITH MOST OF THIS FALLING
IN THE 18-00Z TIMEFRAME. DID TAPER OFF POPS FROM SOUTHWEST TO
NORTHEAST TONIGHT AND SWITCHED WORDING OVER TO FLURRIES ACROSS THE
WESTERN SOUTH PLAINS FOR A FEW HOURS BEFORE MIDNIGHT AS THE
ATMOSPHERE DRIES OUT ONCE THE SYSTEM PASSES BY.  SNOW WILL LINGER
ACROSS THE NORTHERN ROLLING PLAINS THROUGH EARLY WEDNESDAY MORNING
BUT AMOUNTS SHOULD BE LIGHT.  LOW TEMPERATURES OVERNIGHT WILL DEPEND
ON HOW FAST CLOUD COVER WILL CLEAR OUT BUT EXPECT ANOTHER CHILLY
NIGHT...ESPECIALLY IF SKIES GO CLEAR AND SNOWPACK IS ENOUGH TO ALLOW
WIDESPREAD RADIATIONAL COOLING.

JORDAN

LONG TERM...
ACTIVE SOUTHERN STREAM TROF WILL HAVE EXITED THE AREA BY WED MORNING
WITH W-NWLY FLOW FOLLOWING SUIT. MOISTURE-STARVED IMPULSE FOLLOWING
ON THE HEELS OF TODAY/S WAVE WILL AT THE VERY LEAST SERVE TO
AMPLIFY AMPLIFY WINDS THROUGHOUT THE COLUMN ON WED AND EVEN WITH THE
ANTICIPATED SNOWFALL FROM TODAY...FORECAST SOUNDINGS REVEAL
LIMITED MIXING WILL BE REQUIRED TO TAP INTO SOME OF THIS STRONGER
MOMENTUM. COULD SEE A BIT OF BLOWING SNOW EARLY WEDNESDAY...BUT
SPEEDS OVERALL LOOK TO REMAIN BELOW 20 KNOTS. HAVE CONTINUED TO
UNDERCUT MOS FOR HIGH TEMPS WED IN LIGHT OF THE ANTICIPATED LAYER
OF SNOW...BUT WITH AMPLE WESTERLY WINDS IT STILL APPEARS LOW-MID
40S SHOULD EASILY BE REACHED AREA WIDE.

YET ANOTHER SHORTWAVE TROF IS EXPECTED BY THURSDAY AND THIS ONE
APPEARS TO HAVE A BIT MORE MOISTURE AND MORE IMPORTANTLY A COLD
FRONT TO AID IN ASCENT. POTENTIAL /ALBEIT LIMITED/ EXISTS FOR SOME
-SHSN OR FLURRIES IN THE NRN ZONES...BUT WILL KEEP MENTION OUT FOR
NOW AS SOUNDINGS ONLY REVEAL SATURATION IN THE MID LEVELS. AM WARY
OF SOME PROGS SHOWING TEMPS REBOUNDING TO AOA NORMAL TERRITORY BY
NEW YEAR/S DAY AS WINDS VEER SWLY IN THE WAKE OF THURSDAY/S FRONT.
AS SUCH WILL EMPLOY CONSERVATIVE WARMING BEFORE NWLY UPPER FLOW
DELIVERS ANOTHER COLD FRONT FOR THE HOLIDAY WEEKEND.

THEREAFTER...GLOBAL MODELS SUGGEST THE SYNOPTIC PATTERN WILL ACQUIRE
A SHARPER +PNA PATTERN INTO EARLY NEXT RESULTING IN A MORE NORTHERLY
COMPONENT TO THE FLOW ALOFT. PRECIP IN THIS PATTERN IS TYPICALLY
SCARCE...SO FORECAST CHALLENGES BOIL DOWN TO TEMPS AND POSSIBLY LOW
CLOUDS GIVEN A PERSISTENT NELY UPSLOPE FLOW. MAX TEMPS WITHIN
THIS FLOW LOOK TO HOLD BELOW NORMAL AFTER NEW YEAR/S DAY WITH
POTENTIALLY EVEN COLDER TEMPS THAN ARE CURRENTLY FORECAST GIVEN AN
IMPRESSIVE 1050-1053MB ARCTIC HIGH DRAINING INTO THE GREAT PLAINS.

&&

.PRELIMINARY POINT TEMPS/POPS...
FRIONA        32  20  43  23  39 /  90  20   0  10  10
TULIA         33  23  44  25  38 /  70  30   0  10  10
PLAINVIEW     33  22  44  26  39 /  80  30   0  10  10
LEVELLAND     32  22  44  27  42 /  90  20   0  10  10
LUBBOCK       33  23  44  28  41 /  90  30   0  10  10
DENVER CITY   33  22  46  29  45 /  90  20   0  10  10
BROWNFIELD    33  23  46  30  44 /  90  20   0  10  10
CHILDRESS     35  26  46  26  41 /  80  40   0  10  10
SPUR          34  26  46  29  42 /  90  30   0  10  10
ASPERMONT     33  26  49  31  42 /  90  30   0  10  10

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 9 AM THIS MORNING TO 9 PM CST THIS
EVENING FOR THE FOLLOWING ZONES: TXZ021>044.

&&

14/93/14

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LUBBOCK TX
600 AM CST TUE DEC 29 2009

TXZ021>044-301200-
PARMER-CASTRO-SWISHER-BRISCOE-HALL-CHILDRESS-BAILEY-LAMB-HALE-
FLOYD-MOTLEY-COTTLE-COCHRAN-HOCKLEY-LUBBOCK-CROSBY-DICKENS-KING-
YOAKUM-TERRY-LYNN-GARZA-KENT-STONEWALL-
600 AM CST TUE DEC 29 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE EXTREME SOUTHERN TEXAS
PANHANDLE...SOUTH PLAINS AND ROLLING PLAINS.

.DAY ONE...TODAY AND TONIGHT

A STRONG WINTER STORM WILL MOVE OVER THE REGION TODAY BRINGING
ACCUMULATING SNOWFALL TO THE AREA. SNOW ACCUMULATION OF 1 TO 3
INCHES WITH ISOLATED HIGHER AMOUNTS IS EXPECTED...STARTING BY
MID MORNING AND THEN TAPERING OFF BY TONIGHT.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS AND COOPERATIVE OBSERVERS ARE ENCOURAGED TO REPORT
SNOWFALL MEASUREMENTS TO THE NATIONAL WEATHER SERVICE.

JORDAN