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000
FXUS64 KLUB 050550
AFDLUB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
1150 PM CST WED DEC 4 2013

.AVIATION...
VFR CONDITIONS CONTINUE TONIGHT AFTER A COLD FRONT HAS MOVED
THROUGH BOTH TERMINALS. NO SIGN OF ANY MVFR CEILINGS UPSTREAM AT
THIS TIME...SO WILL PUSH ONSET BACK TO 12Z AT LBB TO COINCIDE WITH
THE ONSET OF SCATTERED WINTRY PRECIPITATION AND IMPROVED LOW LEVEL
MOISTURE. KEPT CEILINGS VFR FOR CDS THROUGH 06Z FRIDAY AS
ABUNDANT LOW LEVEL MOISTURE LOOKS TO MOVE IN BEYOND THAT TIME.
LOW CONFIDENCE IN TIMING AND OCCURRENCE OF PRECIPITATION WITHIN 5
NAUTICAL MILES OF EITHER SITE WILL PRECLUDE MENTION AT THIS TIME.

&&

.PREV DISCUSSION... /ISSUED 1034 PM CST WED DEC 4 2013/

UPDATE...
AS OF 10 PM...THE COLD FRONT HAS MOVED THROUGH THE ENTIRE CWA SAVE
FOR YOAKUM COUNTY. TEMPERATURES ARE FALLING QUICKLY AND ARE ALREADY
DOWN NEAR 20 DEGREES ACROSS THE FAR SW TX PANHANDLE. WATER VAPOR
IMAGERY SHOWS A SMALL SHORTWAVE TROUGH APPROACHING THE BAJA
PENINSULA WITH A LARGER TROUGH OVER THE GREAT BASIN. AS THESE
SYSTEMS MOVE EAST WE/LL SEE LIFT INCREASE ACROSS THE AREA AFTER
MIDNIGHT WITH SOME LIGHT PRECIP DEVELOPING EARLY WED MORNING.
DEPENDING ON JUST HOW QUICKLY PRECIP DEVELOPS...THERE MAY BE A
SHORT WINDOW WHERE PRECIP COULD FALL AS RAIN ACROSS OUR FAR
SOUTHERN COUNTIES BEFORE IT SWITCHES TO FRZG RAIN AND SLEET.
AMOUNTS IN THE MORNING SHOULD BE ON THE LIGHT SIDE AND LIKELY
FAVOR THE SOUTHERN AND WESTERN ZONES. THOUGH EVEN LIGHT ICE AND
SLEET ACCUMULATIONS WILL MAKE FOR HAZARDOUS TRAVEL CONDITIONS.
MOST THE LATEST GUIDANCE STILL SUGGESTS THAT MORE WIDESPREAD AND
POTENTIALLY HEAVIER PRECIP WILL DEVELOP THURSDAY EVENING.
UNFORTUNATELY...THERE IS QUITE A BIT OF UNCERTAINTY WITH THE THE
LOCATION AND AMOUNT OF ANY HEAVIER PRECIP. THE LATEST NAM AND MANY SREF
MEMBERS HAVE BACKED OFF ON SNOW AMOUNTS ACROSS THE ENTIRE
AREA...ESPECIALLY THE NW...AND NOW INDICATES A POTENTIAL 1 TO 2
INCH BAND ACROSS THE SRN ROLLING PLAINS THU NIGHT. THE GFS ON THE
OTHER HAND HAS A MUCH LARGE SWATH OF 2 TO 4 INCHES RUNNING SW-NE
FROM LYNN COUNTY TO CHILDRESS COUNTY...AGAIN MISSING THE NW. ENSEMBLES
PRETTY MUCH RUN THE GAMBIT BETWEEN THESE TWO SOLUTIONS. BUT IN THE
MEAN...THERE IS NOT MUCH SUGGESTION OF SNOWFALL OF MORE THAN 1 TO 3
INCHES OR ICE ACCUMULATIONS GREATER THAN A COUPLE TENTHS.
SO...WE/VE DECIDED TO REPLACE THE WINTER STORM WATCH WITH A WINTER
WEATHER ADVISORY. WE STILL HAVE SOME CONCERN FOR REACHING WARNING
AMOUNTS AS THERE ARE HINTS OF A ENHANCED SW-NE BAND OF SNOW AND
SLEET IN SEVERAL MODEL SOLUTIONS...FOCUSED MAINLY ON THE CENTRAL
OR NORTHERN ROLLING PLAINS LATE THURSDAY NIGHT...BUT CONFIDENCE IS
TOO LOW TO ISSUE A WINTER STORM WARNING AT THIS TIME. SUBSEQUENT
FORECASTS MAY YET IMPROVE CONFIDENCE AND A WARNING IS NOT OUT OF
THE QUESTION.

PREV DISCUSSION... /ISSUED 356 PM CST WED DEC 4 2013/

SHORT TERM...
ANOTHER CHALLENGING BOUT OF WINTER WEATHER FOR THIS FORECAST WITH
PLENTY OF UNCERTAINTIES...BUT LET US START WITH WHAT IS OF HIGH
CONFIDENCE. IT WILL GET MUCH COLDER! THE COLD FRONT SLOWLY
DRIFTED INTO THE LUBBOCK AREA AND HUNG AROUND A FEW HOURS BUT
RETREATED NORTH AND EAST. IN FACT...A MORNING HIGH OF 64 DEGREES
OCCURRED THIS MORNING HERE AT THE WFO DROPPING TO 57 AFTER FROPA.
PERHAPS 15 MINS LATER...TEMPS WERE ON THE RISE AND SIT AT 73 AS OF
THIS WRITING. NEVERTHELESS...WITH THE LOSS OF INSOLATION...THE
FRONT WILL PUSH SOUTHWEST ACROSS THE AREA AND COMPLETELY ENVELOP
OUR CWFA BY SUNRISE. WINDS WILL BE A BIT BREEZY BEHIND THE
BOUNDARY BUT SHOULD REMAIN CLEAR OF ADVISORY LEVELS.

THE COLD AIR MASS IS BEING DRIVEN BY A STRONG LOW OVER THE SOUTHERN
CANADIAN PRAIRIES.  THE LEAD WAVE IS APPROACHING WEST TEXAS NOW AND
ANOTHER STRONGER DISTURBANCE WILL APPROACH FRIDAY EVENING. WITH
TEMPERATURES DROPPING QUICKLY...A WINTRY MIX IS EXPECTED.

THINGS SHOULD REMAIN DRY THIS EVENING THOUGH INCREASING MID AND
UPPER LEVEL MOISTURE WILL PERSIST OVERNIGHT. WE MAY SEE SOME
LIGHT FZRA/FZDZ MAINLY ACROSS THE ROLLING PLAINS EARLY THURSDAY
MORNING BEFORE SUNRISE WITH BETTER PRECIPITATION OPPORTUNITIES
THROUGHOUT THE DAY. AT PRESENT...THE HIGHEST POPS ARE ALONG THE
SOUTHERN ROLLING PLAINS...SOUTHERN AND WESTERN SOUTH PLAINS AND
SOUTHWESTERN TEXAS PANHANDLE. LESS PLENTIFUL MOISTURE LOOKS TO BE
IN PLACE ACROSS THE NORTHERN ROLLING PLAINS AND SOUTHEASTERN
PANHANDLE. PRECIP TYPE WILL RANGE FROM PREDOMINANTLY SNOW IN THE
FAR NW TO MOSTLY RAIN/FREEZING RAIN IN THE SOUTHEAST. AREAS IN
BETWEEN WILL SEE A PERIODIC MIX OF SNOW...SLEET...AND FREEZING
RAIN. THE FREEZING RAIN PROSPECTS APPEAR SOMEWHAT LIMITED ACROSS
THE SOUTH PLAINS AS THE COLD AIR DEPTH SHOULD BE THICKER THAN WHAT
IS PROGGED OVER THE SRN ROLLING PLAINS.

AS IS OFTEN THE CASE...GUIDANCE IS QUITE MIXED WITH RESPECT TO
PRECIP LOCATIONS AND AMOUNTS. HAVE THEREFORE TRENDED THINGS
TOWARD CLIMATOLOGICAL EXPECTATIONS OF A PASSING OPEN WAVE THOUGH
HAVE INCREASED SNOW/ICE ACCUMULATIONS A BIT GIVEN THE COLDER-THAN-
TYPICAL NATURE OF THIS SYSTEM. THE GENERAL CONSENSUS IS THAT THE
SE AND NW WILL BE THE FAVORED AREAS FOR PRECIPITATION.
HOWEVER...THERE ARE SOME INDICATIONS OF CSI POTENTIAL WHICH COULD
LOCALLY ENHANCE RATES PARTICULARLY EAST OF THE US 385 CORRIDOR
THURSDAY MORNING AND AFTERNOON. STORM TOTAL SNOW AND ICE LOOK TO
BE ON TRACK TOWARD ADVISORY MORE SO THAN WARNING CRITERIA.
HOWEVER...GIVEN THE UNCERTAINTIES...WILL CONTINUE THE WINTER STORM
WATCH AS IT MOST CLOSELY PARALLELS WHAT IS EXPECTED GIVEN THE
VARIANCE OF UNCERTAINTY.

LOWS TONIGHT SHOULD BE DOWN INTO THE 20S /TEENS N-NW/ WITH 20S FOR
HIGHS ON THURSDAY. CLOUDS WILL BE PLENTIFUL AND INCREASING
TONIGHT.

WHILE POPS ARE GENEROUS MOST LOCATIONS...AMOUNTS ARE NOT EXPECTED TO
BE PARTICULARLY HIGH. HOWEVER...GIVEN THE COLD TEMPS...ANY
PRECIPITATION WHICH DOES FALL WILL QUICKLY DEGRADE TRAVEL
CONDITIONS. ANY AREA WHICH DOES SEE JUST A BIT OF ICE WILL SEE A
SHARP INCREASE IN MOTOR VEHICLE ACCIDENTS...WHICH IS OUR PRIMARY
CONCERN FOR THIS STORM SYSTEM ALONG WITH THE BITTERLY COLD
TEMPERATURES.

LONG TERM...
WINTRY PRECIPITATION WILL BE ONGOING THURSDAY NIGHT WITH BEST
CHANCES OF ICE AND SNOW ACCUMULATION FROM THURSDAY NIGHT THROUGH
EARLY FRIDAY MORNING. DIVERGENCE FROM AN UPPER LEVEL JET STREAK WILL
BE MAXIMIZED OVER OKLAHOMA EXTENDING BACK INTO THE TEXAS PANHANDLE
AND SOUTH PLAINS OF WEST TEXAS. Q-VECTOR CONVERGENCE WILL FIRST
ESCALATE OVER THE SOUTHWESTERN TEXAS PANHANDLE THURSDAY EVENING AND
THEN WEAKEN AND MOVE EAST BY FRIDAY MORNING. THERE WILL LIKELY BE
SOME FRONTOGENETICAL BANDING COMBINING WITH THE UPPER LIFT SOMEWHERE
ACROSS THE AREA WITH GREATEST CHANCES OVER THE TEXAS PANHANDLE. CSI
IS EVEN WITHIN THE REALM OF POSSIBILITIES. THE BEST AREAS FOR
BANDING CONTINUE TO BE THE CLIMATOLOGICAL FAVORED AREA OF THE
SOUTHWESTERN TEXAS PANHANDLE. ISENTROPIC LIFT WILL START OUT STRONG
ON THURSDAY EVENING BUT WEAKEN THROUGH THE NIGHT AND TURN TO
DOWNGLIDE BY 12Z FRIDAY. THEREFORE LIFT WILL BE GREATEST FROM THE
00Z TO 06Z TIME PERIOD AND WANING BY MID MORNING ON FRIDAY.

A DIFFICULT PRECIPITATION TYPE FORECAST LINGERS IN THIS FORECAST
CYCLE. SOUNDINGS SHOW THE EVENING BEGINNING SATURATED BUT QUICKLY
DRYING OUT AT MID AND UPPER LEVELS FROM THE NORTHWEST TO SOUTHEAST.
MOST AREAS THAT START OUT AS SNOW WILL LIKELY TRANSITION TO A WINTRY
MIX OF SLEET/SNOW/FREEZING RAIN AS THIS DRYING ALOFT ENTERS THE
REGION. ACROSS THE SOUTHWESTERN PANHANDLE...LOW LEVEL TEMPERATURES
MAY BE COLD ENOUGH FOR ONLY SLEET AND SNOW. THE SAME IS EXPECTED FOR
THE SOUTHEASTERN PANHANDLE. THE ONLY LOCATION WHERE A SIGNIFICANT
WARM NOSE WILL BE PREVALENT WILL BE ACROSS THE SOUTHERN ROLLING
PLAINS. MODELS PROG AROUND A 2-4C WARM LAYER WITH A SUBFREEZING
LAYER GREATER THAN 3KFT. THEREFORE...MOSTLY SLEET AND FREEZING RAIN
IS EXPECTED IN THIS LOCATION. BETWEEN THESE TWO LOCATIONS...ACROSS
THE CENTRAL SOUTH PLAINS WILL LIKELY SEE A WINTRY MIX BUT VERY LIGHT
ACCUMULATIONS OF BOTH ICE AND SNOW.

FRIDAY WILL SEE A LULL IN PRECIPITATION BEFORE THE NEXT TROUGH LOADS
UP IN THE SOUTHWESTERN US. THIS WILL CREATE MOIST ISENTROPIC LIFT ON
SATURDAY OUT AHEAD OF THIS SYSTEM. HOWEVER...LIFT WILL BE VERY WEAK
IN A SHALLOW MOISTURE LAYER LEADING TO MOSTLY FREEZING DRIZZLE ON
SATURDAY. BEYOND SATURDAY JUST LOOKS COLD. SURFACE RIDGING WILL
CONTINUE TO BE REINFORCED BY STRONG MERIDIONAL FLOW THROUGH EARLY
NEXT WEEK. HOWEVER...A PATTERN CHANGE DOES LOOK POSSIBLE BY THE
MIDDLE TO END OF NEXT WEEK WITH WARMING TEMPERATURES.

&&

.PRELIMINARY POINT TEMPS/POPS...
FRIONA        67  18  21  11  22 /   0  10  70  70  10
TULIA         65  19  21  13  21 /   0  10  50  70  10
PLAINVIEW     68  20  22  14  24 /   0  10  50  70  10
LEVELLAND     71  23  27  16  26 /   0  10  50  70  10
LUBBOCK       69  23  26  16  25 /   0  10  50  70  10
DENVER CITY   72  25  32  18  28 /   0  20  60  70  10
BROWNFIELD    71  25  28  18  26 /   0  20  60  70  10
CHILDRESS     56  25  26  15  24 /   0  10  40  70  10
SPUR          63  25  26  15  24 /   0  20  50  70  20
ASPERMONT     63  27  29  16  26 /   0  20  60  70  20

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 6 AM THURSDAY TO NOON CST FRIDAY
FOR THE FOLLOWING ZONES: TXZ021>044.

&&

$$

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