Area Forecast Discussion
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FXUS64 KLUB 061141 AAA
AFDLUB

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LUBBOCK TX
641 AM CDT WED MAY 6 2015

.AVIATION...
IFR CONDITIONS IN PLACE AT KLBB AND KPVW CURRENTLY WITH MVFR
CONDITIONS AT KCDS. CEILINGS ARE SLOWLY LIFTING SO EXPECT
KLBB/KPVW TO GO MVFR SHORTLY AFTER SUNRISE AND THEN VFR BY LATE
MORNING. AFTER A BRIEF PERIOD OF CLEAR SKIES...EXPECT TO SEE A
PRETTY GOOD CLOUD FIELD DEVELOP THAT WILL HOVER JUST ABOVE MVFR
RANGE. BIGGEST CONCERN AND UNCERTAINTY IN THE FORECAST IS TIMING
AND POSSIBILITY OF THUNDERSTORMS AGAIN THIS AFTERNOON THAT COULD
IMPACT ALL THREE TAF SITES. BETTER CHANCES WILL BE AT KCDS BUT
THERE COULD STILL BE SOME STORMS LATE THIS AFTERNOON INTO THIS
EVENING AT KLBB/KPVW. SEVERE WEATHER REMAINS POSSIBLE AS WELL
WHICH COULD BRING LARGE HAIL AND STRONG WINDS TO ALL THREE TAF
SITES. BEYOND THAT...EXPECT ANOTHER ROUND OF MVFR TO IFR CEILINGS
AT ALL THREE TAF SITES FOR TOMORROW MORNING.

JORDAN.

&&

.PREV DISCUSSION... /ISSUED 412 AM CDT WED MAY 6 2015/

SHORT TERM...
COMPARED TO 24 HOURS AGO...TRANQUIL CONDITIONS ARE IN PLACE ACROSS
THE FORECAST AREA EARLY THIS MORNING.  LOW CLOUDS AND SOME PATCHY
FOG HAVE DEVELOPED ALONG AND JUST EAST OF THE CAPROCK ESCARPMENT
THIS MORNING AND MAY MANAGE TO SPREAD ONTO THE CAPROCK BEFORE
SUNRISE.  COVERAGE IS NOT WIDESPREAD ENOUGH TO PLACE IN THE WEATHER
GRIDS AS VISIBILITIES HAVE REMAINED ABOVE 3 MILES AT ALL LOCATIONS.
ANY POCKETS OF VISIBILITIES BELOW THAT WILL LIKELY BE SHORT LIVED AS
WE HEAD TOWARDS SUNRISE.

BIGGEST QUESTION REMAINS CHANCES FOR CONVECTION THIS AFTERNOON ALONG
WITH SEVERE WEATHER POSSIBILITIES.  RADAR AND WEST TEXAS MESONET OBS
SHOW THE DRYLINE SLOSHING BACK WEST EARLY THIS MORNING WITH LOW 60
DEWPOINTS ACROSS THE ROLLING PLAINS AND EASTERN SOUTH PLAINS.  UPPER
40S ARE STILL IN PLACE ACROSS THE WESTERN SOUTH PLAINS BUT THESE ARE
ALSO GOING TO START INCREASING BEFORE SUNRISE.  BY THIS AFTERNOON...
THE DRYLINE SLOWLY STARTS TO MIX EAST WITH A BROAD MIXING ZONE
BECOMING CENTERED ALONG A DENVER CITY TO SILVERTON LINE.  SEVERAL
CONCERNS REMAIN IN PLACE WITH THIS LOCATION...THE BIGGEST ONE IS
THAT THE MODELS KEEP THE SURFACE TROF AXIS ALONG OR WEST OF THE
TX/NM STATE LINE.  THERE IS SOME REFLECTION OF THIS AS SURFACE WIND
IN THE MOIST SECTOR SHOWS HINTS OF BACKING TO THE SOUTH TO SOUTHEAST
BETWEEN THE 18 AND 00Z OUTPUT TIMES WHILE THE WIND REMAINS OUT OF
THE SOUTHWEST NEAR THE TX/NM STATE LINE.  AMPLE SURFACE MOISTURE
FROM RECENT RAINFALL WILL ALSO EVAPORATE THROUGH THE DAY WHICH MAY
HELP SLOW THE EASTWARD PROGRESSION OF THE DRYLINE...OR AT LEAST MAKE
THE MIXING ZONE MUCH MORE DIFFUSE.  NEXT CONCERN IS THAT THERE IS A
LACK OF LOW-LEVEL CONVERGENCE TO HELP ANY STORMS TO INITIATE SINCE
WIND FIELDS REMAIN PRETTY PARALLEL TO THE MIXING ZONE UNTIL LATE IN
THE DAY.  THROUGH THE DEPTH OF THE ATMOSPHERE...FORECAST SOUNDINGS
SHOW A BIT OF A WEAK CAP THAT ERODES FAIRLY FAST FROM WEST TO EAST
THROUGH THE DAY.  IN THE MOIST SECTOR EAST OF THE DRYLINE
ZONE...WIND PROFILES SHOW DECENT DIRECTIONAL AND SPEED SHEAR THAT
SHOULD ALLOW FOR SOME ORGANIZATION OF CONVECTION.  LOW/MID CLOUDS
AND AMPLE LOW LEVEL MOISTURE WILL ALSO HELP TO SLOW DAYTIME HEATING
WHICH COULD KEEP CONVECTION FROM DEVELOPING UNTIL VERY LATE IN THE
DAY.

CATCHING MY BREATH AFTER ALL OF THAT...THE FORECAST REMAINS PRETTY
MUCH UNCHANGED IN MOST SENSIBLE WEATHER ELEMENTS.  DID INCREASE POPS
ACROSS THE ROLLING PLAINS FOR TONIGHT TO 50 PERCENT AND ADDED
MENTION FOR SEVERE THUNDERSTORMS ALONG AND EAST OF A BROWNFIELD TO
SILVERTON LINE.  PRIMARY THREAT LOOKS TO BE LARGE HAIL EARLY ON BUT
THERE COULD BE AN ISOLATED TORNADO THREAT AROUND AND JUST AFTER
SUNSET AS THE SURFACE WINDS BACK IMPROVING LOW LEVEL SHEAR.  ANY
SUBTLE BOUNDARIES THAT ARE HARD TO PICK OUT IN THE SURFACE ANALYSIS
AS WELL AS TOPOGRAPHY MAY HELP TO ENHANCE THE TORNADO THREAT BUT
THERE IS NO WAY WE CAN PINPOINT THAT AT THIS TIME.  LOCALLY HEAVY
RAINFALL REMAINS A POSSIBILITY AS WELL AS PWAT VALUES ARE A TICK
ABOVE NORMAL AND SLOW STORM MOTIONS TO THE EAST/NORTHEAST COULD
ALLOW FOR CONSIDERABLE RAIN TO FALL IN A SHORT PERIOD OF TIME IN THE
CORE OF THE STRONGER STORMS.

JORDAN

LONG TERM...
THE ACTIVE STRETCH OF EARLY MAY WEATHER THAT WE ARE IN THE MIDST OF
WILL CONTINUE ON THROUGH AT LEAST EARLY THIS WEEKEND...WITH QUIETER
WEATHER EXPECTED FOR EARLY NEXT WEEK. OVERALL...ONLY MINOR
ADJUSTMENTS TO THE ONGOING EXTENDED FORECAST HAVE BEEN MADE THIS
ITERATION.

THE UPPER LEVEL STORM SYSTEM CURRENTLY SINKING SOUTHWARD ACROSS THE
NORTHWEST WILL CONTINUE TO DIG SOUTH THROUGH CALIFORNIA ON THURSDAY
BEFORE IT IS PROGGED TO TURN MORE EASTWARD ON FRIDAY. THE UPPER LOW
IS THEN PROJECTED TO EJECT STEADILY NORTHEASTWARD EMERGING OVER THE
CENTRAL HIGH PLAINS BY LATE THIS WEEKEND. THIS TRACK WILL KEEP WEST
TEXAS SQUARELY UNDER UNSETTLED SOUTHWEST FLOW ALOFT...AND COUPLED
WITH THE DRYLINE IN THE AREA AND PLENTY OF MOISTURE AND
INSTABILITY AVAILABLE ALONG AND EAST OF THE DRYLINE...THIS WILL
SET THE STAGE FOR MORE ROUNDS OF STRONG/SEVERE CONVECTION AND
LOCALLY HEAVY RAINFALL. OF COURSE...THE DEVIL IS IN THE
DETAILS...INCLUDING THE EVOLUTION OF THE PREVIOUS DAY/S CONVECTION
AND HOW IT IMPACTS THE POSITION OF THE DRYLINE AND ANY RESIDUAL
BOUNDARIES EACH DAY. IN ADDITION...ANY SUBTLE RIPPLES/DISTURBANCES
WITHIN THE MID/UPPER FLOW CAN ALSO HAVE A BIG FACTOR ON TIMING
AND LOCATION OF CONVECTION. THAT SAID...IT CAN BE DIFFICULT TO
ASCERTAIN MANY OF THESE DETAILS MORE THAN A DAY OR SO OUT AND WE
HAVE NOT ATTEMPTED TO GET TOO CUTE WITH THE POP/WEATHER GRIDS.
DEEP LAYER SHEAR WILL BE MORE THAN SUFFICIENT FOR STORM
ORGANIZATION /INCLUDING SUPERCELLS/ JUST ABOUT ANY DAY...AND THUS
A THREAT FOR A MYRIAD OF SEVERE WEATHER...AND THIS AGREES WITH THE
SPC OUTLOOKS WHICH HAVE AT LEAST A PORTION OF THE CWA IN 15
PERCENT SEVERE PROBABILITIES FROM TODAY THROUGH SATURDAY.

REGARDING A FEW OF THE DETAILS...IT DOES APPEAR BROAD UPPER SUPPORT
FROM A SHORTWAVE TROUGH CURRENTLY MOVING INTO SOUTHERN CALIFORNIA
AND THE NORTHERN BAJA MAY AFFECT WEST TEXAS EARLY TOMORROW AND BRING
THE PROSPECTS FOR MORNING CONVECTION...THOUGH NWP IS MIXED ON THIS.
OBVIOUSLY...IF CONVECTION DOES TRAVERSE THE CWA EARLY IN THE DAY IT
WOULD HAVE RIPPLE EFFECTS ON HOW ANY AFTERNOON CONVECTION MAY PLAY
OUT. ANOTHER WEAK DISTURBANCE MAY APPROACH FROM THE SOUTHWEST DURING
THE DAY FRIDAY IF THE ECMWF AND GFS ARE CREDIBLE...WITH THE MAIN
LIFT OF THE UPPER LOW CURRENTLY PROGGED TO GRAZE NORTHWEST TEXAS
EARLY ON SATURDAY. SO...NEEDLESS TO SAY...IT SHOULD BE A BUSY
STRETCH. BY LATE SATURDAY IT DOES APPEAR ENOUGH WESTERLY FLOW SHOULD
EFFECTIVELY SHIFT THE MOISTURE/DRYLINE EASTWARD...TAKING THE STORM
THREAT OFF THE CAPROCK AND PERHAPS CLOSE TO OUR EASTERN BORDER. THE
DRYLINE COULD LINGER CLOSE ENOUGH TO KEEP SLIM THUNDER CHANCES GOING
ACROSS THE SOUTHEAST ROLLING PLAINS ON SUNDAY BEFORE A COLD FRONT
FOLLOWS WITH COOLER AND DRIER AIR TO BEGIN NEXT WEEK.

MILD NIGHTS AND SEASONABLY WARM AFTERNOONS WILL BE THE THEME THROUGH
SATURDAY BEFORE TEMPERATURES COOL LATE WEEKEND INTO EARLY NEXT WEEK
BEHIND THE TROUGH PASSAGE AND COLD FRONT.

&&

.PRELIMINARY POINT TEMPS/POPS...
FRIONA        78  51  79  50 /   0  10  20  20
TULIA         81  58  79  54 /  10  20  40  20
PLAINVIEW     81  59  79  55 /  10  30  40  30
LEVELLAND     82  59  82  55 /  10  20  30  30
LUBBOCK       83  61  81  58 /  10  30  30  30
DENVER CITY   83  59  82  54 /  10  20  20  30
BROWNFIELD    84  60  84  56 /  10  30  30  30
CHILDRESS     85  63  81  62 /  20  50  50  40
SPUR          83  63  80  60 /  30  40  40  40
ASPERMONT     84  64  82  63 /  30  50  50  30

&&

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

$$


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