Winter Storm in Texas, January 27 to 28, 2001

SOUTH PLAINS AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
245 AM CST SAT JAN 27 2001

MAJOR WINTER STORM IS BEARING DOWN ON WEST TEXAS AND IT LOOKS LIKE A
PLETHORA OF PRECIPITATION TYPES WILL EXIST ACROSS OUR COUNTY FORECAST
AREA. UPPER LOW IS DEEPENING AS IT DIGS SOUTHEASTWARD ACROSS
SOUTHERN CALIFORNIA AND INTO WESTERN ARIZONA TONIGHT. AS LOW MOVES
CLOSER...BROAD AREA OF UPPER DIFLUENCE AND SYNOPTIC LIFT WILL MOVE
INTO THE SOUTHERN HIGH PLAINS WITH STRONG WARM AIR ADVECTION PATTERN
INITIATING WIDESPREAD PRECIPITATION. COLD AIR WILL DEEPEN OVER THE
AREA AS NE/E WINDS COOL THE BOUNDARY LAYER TO NEAR OR BELOW FREEZING
OVER MOST OF THE AREA. ALSO...ABUNDANT MOISTURE FROM SOUTH TEXAS IN
850 TO 750 MB LAYER WILL INCREASE PRECIPITABLE WATER VALUES TO OVER
HALF AN INCH AS ISENTROPIC UPGLIDE TRANSPORTS IMPRESSIVE AMOUNTS OF
MOISTURE OVER THE COLD AIR.

THE PRECIPITATION LOOKS AS IF IT WILL HAVE A HARD TIME GETTING
STARTED UNTIL AFTER 18Z. FROM THERE ON...THE LIFT WILL CONTINUE TO
INCREASE OWING TO CONVEYER BELT UPGLIDE AIDED BY INCREASING
DIVERGENCE ALOFT. BY THIS EVENING...120 KNOT PLUS 300 MB JET WILL
APPROACH WESTERN COUNTIES. LIFT WILL BE MAXIMIZED AROUND MIDNIGHT
TONIGHT...WITH DEEP LAYER LIFT AND MOISTURE RESULTING IN
PRECIPITATION AMOUNTS OVER HALF AN INCH. THIS WILL TRANSLATE INTO
SEVERAL INCHES OF SNOW FOR THE NORTHWESTERN SOUTH PLAINS AND THE
SOUTHWESTERN PANHANDLE WHERE INITIAL INCLINATION IS TO KEEP
ACCUMULATIONS AT 6 TO 8 INCHES...ALTHOUGH FEEL SOME LOCALLY HEAVIER
AMOUNTS WILL BE POSSIBLE. ACROSS THE WESTERN AND CENTRAL SOUTH
PLAINS...FORECAST SOUNDINGS SUPPORT FREEZING RAIN OR SLEET. COULD
SEE SOME SIGNIFICANT ICE ACCUMULATIONS. THE SOUTHERN LOW ROLLING
PLAINS MAY START OUT WITH RAIN AND THEN CHANGEOVER TO FREEZING RAIN
DURING THE MID TO LATE AFTERNOON. IN ANY EVENT...WILL GO WITH WINTER
STORM WARNING ALL ZONES TODAY AND TONIGHT.

ETA IS STILL FORECASTING ABOVE FREEZING LAYER ALOFT IN THE 700 TO
800 MB LEVEL OVER KLBB AND SURFACE/BOUNDARY LAYER TEMPERATURES
COOLING INTO THE MID TO UPPER 20S. STRENGTH OF WARM LAYER WOULD
ALMOST SUGGEST FREEZING RAIN ONLY...BUT AVN IS COOLER ALOFT AND
STILL FEEL THAT SLEET WILL OCCUR AS WELL. IN THE NORTHWESTERN
COUNTIES...THE COLUMN WILL SUPPORT SNOW BY LATE AFTERNOON...BUT SOME
SLEET MAY MIX IN INITIALLY UNTIL DEPTH OF MOISTURE INCREASES TO
PRODUCE SOME FEEDING/SEEDING EFFECTS.

OTHER CONCERN IS PRECIPITATION AMOUNTS BEING ENHANCED BY ELEVATED
CONVECTION. 700-500 MB LAPSE RATES DONT LOOK QUITE AS IMPRESSIVE AS
LAST NIGHT...BUT WITH SUSTAINED DEEP LAYER LIFT AND SUBSEQUENT
COOLING ALOFT...WOULD NOT RULE OUT SOME UPRIGHT CONVECTION
ESPECIALLY OVER WESTERN/NW COUNTIES THIS EVE OR TONIGHT. A QUICK
LOOK AT CROSS SECTIONS SHOWS AT LEAST THE POTENTIAL FOR SOME CSI OR
SLANTWISE CONVECTION OVER MAINLY THE SOUTHEASTERN HALF OF THE AREA.
THIS OF COURSE IF UPRIGHT CONVECTION DOES NOT DOMINATE. SOMETHING
FOR LATER SHIFTS TO WATCH. THE PRECIPITATION SHOULD FINALLY BEGIN TO
TAPER OFF DURING THE DAY ON SUNDAY AT WHICH TIME IT SHOULD CHANGE
OVER TO MOSTLY SNOW ACROSS THE REMAINDER OF THE AREA AS THE UPPER
LOW MOVES FROM COLORADO INTO WESTERN KS.  COULD SEE SOME WRAP AROUND
PRECIP. ON WESTERN SIDE OF LOW ON MONDAY SO LIGHT SNOW OR FLURRIES
(OR CHANGEOVER TO RAIN) MAY OCCUR THEN. MODERATING TEMPERATURES FOR
TUESDAY BEFORE NEXT SYSTEM BEGINS TO AFFECT AREA AS EARLY AS WED.
PLAN NO CHANGES TO EXTENDED. PRELIM NUMBERS FOLLOW. THANKS COORD ABQ
AND AMA.

FRIONA/TULIA         30/25/30/24  9987
BROWNFIELD/LUBBOCK   32/28/34/27  9987
CHILDRESS            32/28/33/27  7997
ASPERMONT            36/30/36/30  7997

.LUB...WINTER STORM WARNING TODAY AND TONIGHT ZONES 21>44.

JAMES