Area Forecast Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS64 KLUB 221148
AFDLUB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
548 AM CST MON DEC 22 2014

.AVIATION...
VFR TODAY WITH MVFR AND IFR POSSIBLE BY EARLY TUE MORNING. WEAK
COLD FROPA FROM NEAR TCC-CDS AT 1130Z WILL BRING 15-20 KNOT NLY
WINDS TO THE TERMINALS THIS MORNING BEFORE SPEEDS SCALE BACK IN
THE AFTERNOON.

DEVELOPING STORM SYSTEM BY TONIGHT SPELLS GOOD CHANCES FOR RA AT
LBB AND PVW BEFORE COLDER AIR AFTER 06Z THREATENS TO CHANGE THIS
OVER TO SN. COULD SEE SNOW ACCUMULATIONS OF 1 INCH OR LESS WITH
THE BEST CHANCES FAVORING PVW. CIGS SHOULD ALSO LOWER OVERNIGHT-
BUT LIKE THE SNOW THREAT...THE WINDOW FOR MVFR AND IFR DOESN/T
OPEN UNTIL VERY LATE IN THIS FORECAST PERIOD...SO NO EXPLICIT TAF
MENTION WILL BE MADE FOR EITHER ATTM.

&&

.PREV DISCUSSION... /ISSUED 435 AM CST MON DEC 22 2014/

SHORT TERM...
SURFACE MAP AT 09Z FEATURED A SURFACE TROUGH ALONG THE HIGHWAY 83
CORRIDOR WITH A SEMI-AMBIGUOUS FRONTAL BOUNDARY BISECTING THE TX
PANHANDLE FROM ABOUT MEMPHIS NW TO DALHART AHEAD OF WEAK PRESSURE
RISES. THIS FRONT WILL ACCELERATE SOUTH THIS MORNING UNDER STRONGER
CYCLONIC NW FLOW BEFORE EXITING OUR CWA BEFORE NOON...HOWEVER WITH
THE UNUSUALLY MILD START TO THE MORNING TEMPS TODAY WON/T HAVE MUCH
TROUBLE ENDING ABOVE CLIMO ONCE AGAIN.

FORECAST CHALLENGES RAMP UP TONIGHT AND EARLY TUE A.M. AS MEAN
TROUGHING OVER THE GREAT PLAINS SHARPENS AND EVENTUALLY CLOSES OFF
AN ELONGATED UPPER LOW IN KS/NE. THIS PROCESS WILL ENCOURAGE HEIGHT
FALLS ACROSS OUR REGION NEAR SUNSET BEFORE PEAKING OVERNIGHT. ADD TO
THIS A LONG FETCH OF MID-LEVEL PACIFIC MOISTURE EXTENDING BACK TO
THE NRN ROCKIES AND THE STAGE LOOKS SET FOR AGGRESSIVE TOP-DOWN
MOISTENING AND EVENTUALLY PRECIP. MODELS AGREE THAT THE GREATEST
FOCUS FOR ASCENT IS TIED TO FN FORCING ALONG THE SLOPING FRONTAL
LAYER FROM 850-600 MB...SO MUCH SO THAT A 700MB WAVE/BRIEF LOW GENS
UP BY 06Z. UPPER JET SUPPORT IS ALMOST NIL...SO LIFT AS A WHOLE WILL
BE CONCENTRATED IN THE LOWER HALF OF THE TROPOSPHERE WHICH IS GOOD
NEWS FOR POPS. NUDGED POPS UP TO 70 PERCENT FOR MUCH OF THE CAPROCK
OVERNIGHT AS THE BEST FN FORCING IS FOCUSED OVER THIS REGION FOR
SEVERAL HOURS. WPC QPF MAY NOT BE TOO FAR OFF GIVEN THE LONGER
RESIDENCE TIME OF THIS LIFT COMBINED WITH ENHANCED PRECIP RATES NEAR
THE AFOREMENTIONED 700MB WAVE.

WE/VE HAD BIGGER HEADACHES FORECASTING PRECIP PHASES BEFORE...BUT
THIS EVENT LOOKS MORE STRAIGHTFORWARD WITH RAIN CHANGING TO SNOW
OVER TIME. DETERMINING THE LOCATION OF THIS TRANSITION LINE IS STILL
A BLACK ART...BUT THE 00Z MODEL TEMP PROFILES FAVOR SNOW IN OUR FAR
NWRN COUNTIES BY 03Z WITH A STEADY EXPANSION S-SE THRU 12Z. AREAS
OFF THE CAPROCK SHOW LITTLE OPPORTUNITY TO ERADICATE THEIR DEEP
MELTING LAYER OF NEARLY 4K FEET THICK...SO ALL RAIN REMAINS THE
FORECAST FOR OUR ERN ZONES. ON THE CAPROCK...MARGINAL 2M AND GROUND
TEMPS POSE A PROBLEM FOR SNOW ACCUMS AS NO TRULY COLD AIR IS EVIDENT
UPSTREAM THIS MORNING. HOWEVER...MID-LEVEL INSTABILITY CAN EASILY
COMPENSATE FOR THESE MARGINAL TEMPS AND YIELD SNOW ACCUMS. SUCH IS
THE CASE IN THIS SETUP AS MODEL SOUNDINGS FOCUS THE STEEPEST LAPSE
RATES DIRECTLY IN THE DENDRITIC GROWTH ZONE. STILL...WE/RE KEEPING
SNOW ACCUMS OF 1 INCH OR LESS GIVEN OVERWHELMING SUPPORT FOR THESE
TOTALS FROM SREF PLUME DATA. GREATEST PROBABILITY FOR AN INCH STILL
FAVORS OUR NWRN ZONES WHERE LL TEMPS WILL BE LESS MARGINAL AND THE
DENDRITIC GROWTH ZONE SATURATION IS ALSO PROGGED TO BE THE DEEPEST.

LONG TERM...
SNOW/PRECIPITATION WILL COME TO A FAIRLY QUICK END TUESDAY MORNING
FROM NORTH TO SOUTH AS THE TROF AXIS SLIDES SOUTHEAST OF THE AREA.
MODELS STILL TRY TO GENERATE SOME PRECIPITATION AFTER 18Z AS A
SECOND LOBE OF ENERGY DIVES SOUTHEAST BEHIND THE MAIN
SYSTEM...HOWEVER ALL AVAILABLE MOISTURE WILL HAVE PUSHED SOUTHEAST
OF THE AREA AND SUBSIDENCE WILL ALSO HELP TO DRY THINGS OUT. A
TIGHT PRESSURE GRADIENT WILL DEVELOP ACROSS THE AREA THROUGH THE
DAY TUESDAY WHICH WILL HELP TO RAMP A NORTH WIND UP INTO THE 20 TO
30 MPH RANGE MAKING IT FEEL RATHER BRISK. HIGHS WILL STRUGGLE TO
CLIMB OUT OF THE 30S FOR ANY AREAS THAT DO HAVE SNOW ON THE GROUND
WHILE THE MAJORITY OF THE FORECAST AREA MAKES IT INTO THE UPPER 40S
TO LOWER 50S.

WEDNESDAY WILL SEE A RETURN TO A WESTERLY SURFACE WIND AND
TEMPERATURES WARMING INTO THE 50S ACROSS THE ENTIRE FORECAST AREA.
CHRISTMAS DAY STILL REMAINS A BIT UNCERTAIN IN HOW STRONG WIND
SPEEDS WILL BECOME DURING THE DAY. MODELS HAVE BEEN SLOWLY
DECREASING WIND SPEEDS OVER THE PAST SEVERAL RUNS AS WE HAVE GONE
THROUGH THE FULL RANGE OF SOLUTIONS...CLOSED LOW...OPEN
WAVE...ZONAL FLOW...AND NOW BACK TRENDING TOWARDS AN APPROACHING
WAVE. REGARDLESS...CHRISTMAS DAY WILL BE UNSEASONABLY WARM WITH
HIGHS IN THE MID TO UPPER 60S.

AS THE AFOREMENTIONED POSSIBLE WAVE MOVES OUT INTO THE CENTRAL
PLAINS...A COLD FRONT WILL MOVE INTO THE REGION DURING THE DAY
FRIDAY. THIS WILL KNOCK HIGH TEMPERATURES BACK 15 DEGREES AND TO
NEAR NORMAL AS STRONG COLD AIR ADVECTION TAKES PLACE THROUGH THE
DAY. THIS AIRMASS WILL REMAIN OVER THE REGION THROUGH THE HOLIDAY
WEEKEND WITH TEMPERATURES SATURDAY DROPPING A BIT MORE INTO UPPER
40S BEFORE WARMING SOME FOR SUNDAY. ECMWF IS HINTING AT SOME
PRECIPITATION WITH THE FRONT ON FRIDAY BUT ATMOSPHERE APPEARS TO
BE TOO DRY FOR ANY OF THIS TO REACH THE GROUND AND LEFT THE
FORECAST DRY FOR NOW.

JORDAN

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$

93/14/93





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.