Area Forecast Discussion
Issued by NWS

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720
FXUS64 KLUB 230130
AFDLUB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
730 PM CST MON DEC 22 2014

.AVIATION...
AN ADDITIONAL AVIATION CONCERN HAS ARISEN FROM THREAT OF STRONG
DOWNDRAFT WINDS ASSOCIATED WITH VIRGA SHOWERS MOVING ACROSS THE
AREA. THREAT WILL STEADILY DIMINISH FROM WEST TO EAST THROUGH THE
EARLY MORNG AS THE BOUNDARY LAYER MOISTENS FROM FALLING
TEMPERATURES AND INCREASING PRECIPITATION.
JH
&&

.PREV DISCUSSION... /ISSUED 626 PM CST MON DEC 22 2014/

AVIATION...
PRIMARY AVIATION CONCERNS FOR THE NEXT 12 TO 14 HOURS WILL BE CIGS
DROPPING INTO THE MVFR CATEGORY AT KLBB AND KPVW AS THREAT OF
-SHRA/RA INCREASES AND TRANSITIONS TO -RASN THEN -SN OVERNIGHT.
VSBYS AT THESE LOCATIONS MAY DROP INTO THE MVFR CATEGORY AT
TIMES DURING BRIEF PERIODS OF /HEAVIER/ BANDS OF -SN.
MEANWHILE...OVER AT KCDS...EXPECTING PREDOMINATELY VFR
CONDITIONS DESPITE PASSING -SHRA.

AVIATION CONCERNS WILL QUICKLY SHIFT TO INCREASING WINDS IN WAKE
OF PRECIPITATION TUE MORNG. NORTHERLY WINDS MAY BRIEFLY GUST TO
40KTS AT TIMES ACROSS THE AREA FROM LATE MORNG THROUGH THE END OF
THE FORECAST PERIOD. JH

PREV DISCUSSION... /ISSUED 417 PM CST MON DEC 22 2014/

SHORT TERM...
SATELLITE AND REGIONAL RADAR IMAGERY SHOW THAT LIFT IS ALREADY
BEGINNING TO SPREAD INTO EASTERN NEW MEXICO AND THE WESTERN TX
PANHANDLE AT 4 PM. A STRONG UPPER-LEVEL JET IS DIGGING INTO NRN NM
ON THE WESTERN FLANK OF AND UPPER TROUGH MOVING INTO THE PLAINS. THE
JET WILL HELP DEEPEN THE TROUGH THIS EVENING AND OVERNIGHT...WHICH
WILL THEN SWING SEWD ACROSS WEST TEXAS TUESDAY MORNING. IN
ADDITION...A BAROCLINIC ZONE WILL STRENGTHEN ACROSS THE FA WITH A
850MB TROUGH SETTING UP ACROSS THE PERMIAN BASIN AND A 700 MB
LOW/TROUGH OVERHEAD. THIS WILL RESULT IN A PERIOD OF STRONG
FRONTOGENETICAL AND ISENTROPIC LIFT...WHICH WILL GRADUALLY MIGRATE
SOUTHWARD. QUITE A BIT OF MID-LEVEL MOISTURE IS CAUGHT UP IN THIS
TROUGH AND SOME STEEP MID-LEVEL LAPSE RATES AS WELL. ALL OF THIS TO SAY
THAT THE SETUP LOOKS VERY FAVORABLE FOR WIDESPREAD PRECIP ACROSS
MOST OF THE FA OVERNIGHT. FORECAST QPF AMOUNTS REMAIN QUITE
GENEROUS...RANGING FROM ABOUT A TENTH OF AN INCH IN THE NORTH TO
MORE THAN A HALF INCH IN THE SRN ROLLING PLAINS.

HOWEVER...THE PRIMARY CONCERN IS THE SNOWFALL POTENTIAL AND THIS
REMAINS SOMEWHAT UNCLEAR THIS AFTERNOON. IT APPEARS THAT TEMPS WILL
BE COLD ENOUGH FOR A CHANGEOVER TO SNOW IN OUR NW ZONES WELL BEFORE
MIDNIGHT. HOWEVER...FORCING FOR PRECIP WILL END EARLY IN THAT AREA
AND THERE MAY NOT BE A LARGE WINDOW FOR ACCUMULATION. FARTHER TO THE
SOUTH AND EAST...MORE OF THE INITIAL PRECIP WILL FALL AS
LIQUID...AND THERE IS LOWER CONFIDENCE THAT LOW-LEVEL TEMPERATURES
WILL SUPPORT MUCH SNOW ACCUMULATION...ALTHOUGH WE ARE FAIRLY CERTAIN
THAT WE WILL SEE AT LEAST A MIXTURE ON THE CAPROCK. OFF THE
CAPROCK...PRECIP IS LIKELY TO REMAIN LIQUID THROUGH THE EVENT.
SO...AT THIS TIME SNOWFALL AMOUNTS ARE EXPECTED TO BE ON THE LIGHT
SIDE...AND WE HAVE FORECAST TOTALS RANGING FROM JUST SHY OF TWO
INCHES ALONG THE TX/NM STATE LINE...TO AROUND AN INCH ACROSS THE
CENTRAL SOUTH PLAINS. THE RELATIVELY MILD SURFACE TEMPS SHOULD KEEP
MOST OF THE ACCUMULATIONS CONFINED TO GRASSY AND ELEVATED
SURFACES...AND MOST ROADWAYS COULD REMAIN PROBLEM FREE.
HOWEVER...GIVEN THE DEGREE OF LIFT AND THE POSSIBILITY FOR TEMPS TO
BE SLIGHTLY COOLER THAN FORECAST...THE POTENTIAL REMAINS FOR SOME
GREATER ACCUMULATIONS AND IMPACTS. WE HAVE DECIDED TO ISSUE A WINTER
WEATHER ADVISORY FOR MOST OF THE WESTERN AND CENTRAL SOUTH PLAINS
.TO COVER THE AREA MOST LIKELY TO SEE SOME SIGNIFICANT IMPACTS
FROM SNOW.

AFTER THE PRECIP COMES TO AN END AROUND MIDDAY...WE WILL STILL HAVE
TO CONTEND WITH BLUSTERY NORTH WINDS DEVELOPING IN THE WAKE OF THE
STORM SYSTEM. THE WINDS ARE EXPECTED TO REMAIN JUST SHY OF ADVISORY
SPEEDS...BUT WILL BE GUSTING INTO THE 40S MUCH OF THE DAY AND WILL
KEEP WIND CHILLS IN THE 20S AND 30S WITH TEMPS ONLY WARMING INTO THE
40S FOR MOST LOCATIONS.

THANKS SURROUNDING OFFICES FOR COORDINATION WITH THIS EVENT.

LONG TERM...
CENTRAL PLAINS CLOSED LOW SHEARS OUT LATE TUE WITH ONE LAST PIECE
OF JET ENERGY ROTATING AROUND THE BASE OF THE DEPARTING TROUGH
ACROSS CENTRAL TX. PRIMARY FORCING WITH TRAILING SHORTWV SHOULD BE
WELL EAST OF THE TX PNHDL/ROLLING PLAINS WITH BACK EDGE OF CLOUDS
HANGING IN ACROSS EASTERN COUNTIES THROUGH MUCH OF THE NIGHT.

ATTENTION THEN TURNS TO CHRISTMAS DAY WHEN ANOTHER STORM SYSTEM
BEGINS TO MOVE INTO THE FOUR CORNERS REGION. LEAD ENERGY
SPLITTING AHEAD OF A DEEPENING MID LEVEL TROUGH WILL SUPPORT SFC
CYCLOGENESIS IN THE LEE OF THE ROCKIES. LOW AND MID LEVEL HEIGHT
GRADIENTS ARE STRONG ENOUGH TO SUPPORT WINDY CONDITIONS /20-30
MPH/ CHRISTMAS DAY. H8 THERMAL RIDGING OF 12-14C COMBINED WITH
DOWNSLOPE WINDS SHOULD BE ENOUGH TO HELP BOOST TEMPS INTO THE 60S SO
SIDED WITH WARMER GUIDANCE ON TEMPS. DID NOT INCLUDE ANY BLDU IN
THE GRIDS ATTM AS TIMING OF STRONGEST WINDS STILL A BIT UNCERTAIN
WITH SYSTEM YET TO ENTER THE CONUS U/A NETWORK.

STILL MAJORITY OF MED RANGE SOLUTIONS DEVELOP A LONGWV TROUGH
VCNTY THE ROCKIES BY LATE CHRISTMAS DAY. FROM THAT POINT ON THEIR
IS SOME DISAGREEMENT ON HOW MUCH ENERGY WILL TRY TO HANG BACK
ACROSS THE DESERT SW AS NORTHERN STREAM ENERGY PHASES ACROSS THE
NORTHERN PLAINS. THE DEVELOPING SHORTWV OVER AZ/NM HAS
RAMIFICATIONS COME FRI NIGHT INTO SAT. A STRONG CONTINENTAL POLAR
AIRMASS SHOULD MAKE GOOD HEADWAY ACROSS THE HIGH PLAINS FRI
SETTING UP THE OPPORTUNITY FOR A DEEPLY SATURATED COLUMN AS THE
STORM SYSTEM OUT WEST ARRIVES. AS A RESULT HAVE INCLUDED SLGT CHC
POPS FOR FRI NIGHT INTO SAT ACROSS THE SOUTHERN SOUTH PLAINS AND
ROLLING PLAINS. ECMWF AND CANADIAN REMAIN STRONGER WITH SOUTHERN
SPLIT SYSTEM AND ALSO MUCH COLDER WITH SURFACE ANTICYCLONE SLIDING
INTO THE SOUTHERN PLAINS. AT ANY RATE SAT SHOULD BE THE COLDEST
DAY OF THE 3-7 DAY PERIOD. RETURN FLOW LOOKS TO ESTABLISH ITSELF
LATE IN THE WEEKEND AS MORE WESTERLY/SOUTHWESTERLY FLOW DEVELOPS
IN THE WAKE OF THE DEPARTING TROUGH. HIGH VARIABILITY IN THE
ENSEMBLE MOS NUMBERS FOR FRI INDICATES EQUALLY HIGH UNCERTAINTY IN
THE PROGRESS OF THIS SYSTEM SO POPS LATE IN THE WEEK AND EARLY
WEEKEND WILL LIKELY BE ADJUSTED MANY TIME BEFORE THEN.
&&

.PRELIMINARY POINT TEMPS/POPS...
FRIONA        27  39  20  46  25 /  80  10  10   0   0
TULIA         31  40  25  46  28 /  70  10  10   0   0
PLAINVIEW     31  42  26  46  29 /  80  10  10   0   0
LEVELLAND     30  43  26  47  29 /  80  20   0   0   0
LUBBOCK       31  44  28  48  30 /  80  10  10   0   0
DENVER CITY   31  44  26  47  30 /  70  30   0   0   0
BROWNFIELD    31  43  28  47  30 /  80  20   0   0   0
CHILDRESS     34  48  33  49  30 /  30  10  10  10   0
SPUR          34  46  31  48  32 /  80  20  10   0   0
ASPERMONT     37  49  34  51  32 /  80  30  10   0   0
&&

.LUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 8 AM CST TUESDAY FOR THE FOLLOWING
ZONES: TXZ021-022-027>029-033>035-039-040.
&&

$$

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