Area Forecast Discussion
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069
FXUS64 KLUB 310858
AFDLUB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
358 AM CDT TUE MAR 31 2015

.SHORT TERM...
THE CONVECTIVE FORECAST FOR THIS AFTERNOON AND EVENING IS A
CHALLENGING ONE. WATER VAPOR IMAGERY THIS MORNING SHOWS A SMALL
SOUTHERN STREAM UPPER LOW OVER THE BAJA PENINSULA. DOWNSTREAM OF
THIS...QUITE A BIT OF SUB-TROPICAL MOISTURE WAS STREAMING NEWD
ACROSS NRN MX INTO SW TX. AS THE UPPER LOW MOVES EWD TODAY...A 250MB
JET MAX WILL PULL AWAY FROM THE REGION...ALTHOUGH THE ENTRANCE
REGION MAY NOT BE TOO FAR REMOVED FROM THE ROLLING PLAINS LATE
THIS AFTERNOON. TO THE NORTH OF THE UPPER-LOW...WATER VAPOR AND PV
ANALYSIS SHOWS A REGION OF STRETCHED VORTICITY FROM NRN AZ THROUGH
THE TX PANHANDLE...WITH A COUPLE SMALL-SCALE ROTATIONS LENDING
SOME WEAK LIFT...AND SUPPORTING ISOLD SHOWER ACTIVITY IN THE SE TX
PANHANDLE.

CLOSER TO THE SURFACE...A STRONG SWERLY LLJ HAS HELPED BRING
MOISTURE BACK INTO MUCH THE FORECAST AREA...ALTHOUGH SURFACE
DEWPOINTS WERE ONLY IN THE LOW 40S TO LOW 50S...AND THE SURFACE WIND
FIELD WAS WEAK AND CHAOTIC.

AS THE UPPER LOW TRACKS WELL SOUTH OF EL PASO TODAY...WE EXPECT WEAK
TROUGHINESS AND LARGE-SCALE ASCENT TO MIGRATE ACROSS WEST TEXAS.
INDICATIONS ARE THAT THERE WILL BE A WEAK LOW-LVL CYCLONE SLOWLY
MOVING SOUTH OR SW FROM THE PANHANDLE INTO THE WESTERN SOUTH PLAINS.
THE SURFACE WIND FIELDS SHOULD ROUGHLY REFLECT THIS...WITH N-NW
WINDS INITIALLY PUSHING DRY AIR INTO MUCH OF THE NRN AND CENTRAL
PORTIONS OF THE CWA...BUT THEN SOME MOISTURE MAY WRAP AROUND BACK
INTO THE FAR SE TX PANHANDLE AND NRN ROLLING PLAINS LATE IN THE DAY.
A DRYLINE...IF ONE ACTUALLY FORMS UP...MAY NOT HAVE A TYPICAL N-S
ORIENTATION. MEANWHILE...A WELL-MIXED CBL IS EXPECTED TO DEVELOP
ACROSS MOST OF THE CAPROCK WITH FORECAST SOUNDINGS SHOWING SURFACE
TEMPS IN THE MID 80S...LCL/S AROUND 600 MB WITH STEEP MID-LEVEL
LAPSE RATE AND NO CINH REMAINING BY MID-AFTERNOON. MLCAPE WILL BE
LOW...AROUND 500 J/KG...BUT DCAPE VALUES AROUND 1000 J/KG. WE
EXPECT ISOLATED TO WIDELY SCATTERED T-STORMS TO FORM IN THIS
ENVIRONMENT...PERHAPS FIRST ACROSS THE PERMIAN BASIN INTO THE
TRANS-PECOS VALLEY IN RESPONSE TO WHERE CONVECTIVE TEMPS ARE
FIRST REACHED. THIS ACTIVITY SHOULD GRADUALLY SPREAD E-NEWD. WE
ANTICIPATE THAT DRY MICROBURSTS AND DRY LIGHTNING WILL BE THE MAIN
THREATS WITH THIS ACTIVITY...AND ANY RAINFALL WILL BE SPOTTY.
FARTHER TO THE EAST...CAPES MAY RANGE FROM ABOUT 1000 J/KG OFF THE
CAPROCK TO NEARLY 2000 J/KG OUT IN THE EASTERN ROLLING PLAINS
/NEAR OUR CWA BORDER/...DEPENDING ON IF WE CAN MAINTAIN AN
EASTERLY COMPONENT TO THE WINDS IN THAT AREA. IF THESE CAPES DO
VERIFY...THERE WILL BE GREATER POTENTIAL MORE STORM COVERAGE...
ORGANIZATION AND LONGEVITY...WHICH WILL BRING A GREATER THREAT
FOR LARGE HAIL AND DOWNBURST WINDS.

THE WEAK TROUGHING ALOFT WILL PERSIST TONIGHT...AND KEEP A CHANCE OF
ISOLATED STORMS GOING AT LEAST UNTIL MIDNIGHT...AND POSSIBLY INTO
THE EARLY MORNING AS WELL...MAINLY IN AREAS EAST OF THE CAPROCK.

.LONG TERM...
THE DISTURBANCE DISCUSSED IN THE SHORT TERM WILL BE SHIFTING TO THE
EAST ON WEDNESDAY...THOUGH A WEAK SHORTWAVE TROUGH MAY EMERGE ACROSS
THE CENTRAL HIGH PLAINS LATE IN THE DAY. THIS SECOND WAVE AND
INCREASING WESTERLY FLOW ALOFT WILL HELP TO DEEPEN THE SURFACE
TROUGH IN THE LEE OF THE CENTRAL/SOUTHERN ROCKIES...WITH AN
ATTENDANT DRYLINE EXTENDING FROM NORTH-TO-SOUTH THROUGH THE CWA. THE
LATEST NWP HAS TRENDED A LITTLE FARTHER WEST WITH THE LATE DAY
DRYLINE POSITION...PLACING IT SOMEWHERE NEAR THE EDGE OF THE
CAPROCK. THERE IS A CHANCE ISOLATED CONVECTION COULD DEVELOP ALONG
THE DRYLINE LATE WEDNESDAY AFTERNOON OR EVENING...THOUGH A WEAK
CAP...LIMITED LOW-LEVEL CONVERGENCE AND THE RELATIVELY LACK OF LARGE
SCALE SUPPORT CALL INTO QUESTION WHETHER CONVECTION WILL INITIATE AT
ALL LOCALLY...AND MOST NWP KEEP OUR CWA DRY. THAT SAID...IF
CONVECTION CAN DEVELOP...SBCAPE VALUES OF 1000+ J/KG AND 0-6 KM
SHEAR AROUND 25 KNOTS COULD SUPPORT A STRONG TO SEVERE STORM. WE
HAVE RAISED POPS ACROSS ROUGHLY THE EASTERN HALF OF THE AREA SEVERAL
PERCENTAGE POINTS...INTO THE 10 TO 15 PERCENT RANGE...THOUGH WE
HAVE KEPT THE EXPLICIT MENTION OF THUNDER OUT OF THE FORECAST FOR
NOW...AND WE WILL CONTINUE TO WATCH THIS CLOSELY.

INCREASED WESTERLY FLOW ALOFT WILL GRADUALLY WORK ITS WAY TO THE
SURFACE ON THURSDAY...SHUNTING THE MOISTURE AND ANY LOW THUNDERSTORM
CHANCES FURTHER EASTWARD AND OUT OF THE CWA. INSTEAD...GUSTY AND DRY
DOWNSLOPE WINDS WILL ELEVATE THE FIRE DANGER FOR MUCH OF THE CWA.
THE ONE EXCEPTION TO THIS COULD BE ACROSS THE FAR NORTHEAST ZONES
WHERE A WEAK COLD FRONT MAY ATTEMPT TO SLIP IN AND PROVIDE SLIGHTLY
COOLER TEMPERATURES ALONG WITH LIGHTER WINDS. COOLER AIR WILL THEN
OVERSPREAD THE REMAINDER OF THE CWA BY LATE WEEK AS A COLD FRONT
MOVES THROUGH EARLY FRIDAY IN RESPONSE TO A MORE SIGNIFICANT
SHORTWAVE TROUGH RACING ACROSS THE CENTRAL PLAINS. AFTER
EXPERIENCING TEMPERATURES 10-20 DEGREE ABOVE AVERAGE THE NEXT FEW
DAYS...TEMPERATURES WILL DIP BACK BELOW AVERAGE FRIDAY AND
SATURDAY.

A SOUTHERN STREAM DISTURBANCE IS THEN PROGGED TO QUICKLY APPROACH
FROM THE SOUTHWEST EARLY SUNDAY WHILE RETURN FLOW GRADUALLY DEVELOPS
NEAR THE SURFACE. IT DOES APPEAR MOISTURE RETURN MAY BE
LIMITED...BUT ENOUGH MID/UPPER SUB-TROPICAL MOISTURE COUPLED WITH
LIFT FROM THE APPROACHING WAVE MAY BE SUFFICIENT TO SQUEEZE OUT A
FEW SHOWERS LATE SATURDAY INTO SUNDAY...WITH SPOTS OFF THE CAPROCK
MOST FAVORED. A PERIOD OF SOUTHWEST FLOW ALOFT IS THEN PROJECTED
TO TAKE SHAPE ACROSS THE REGION TO CLOSE OUT THE LONG TERM AS A
BROAD TROUGH MOVES INTO THE WESTERN STATES. THIS WILL SUPPORT A
QUICK WARM UP WITH TEMPERATURES REBOUNDING BACK WELL ABOVE
AVERAGE. A DRYLINE SHOULD ALSO SETUP SOMEWHERE IN THE
REGION...THOUGH IF IT WILL BE THE FOCUS FOR STORM DEVELOPMENT AND
WHETHER OR NOT IT WILL BE ABLE TO HOLD IN OUR EASTERN ZONES DURING
PEAK HEATING REMAIN IN DOUBT AND A DRY FORECAST HAS BEEN
MAINTAINED BEYOND SUNDAY.

&&

.FIRE WEATHER...
RELATIVE HUMIDITY VALUES ARE EXPECTED TO DROP BELOW
20 PERCENT ACROSS MUCH OF THE WESTERN CAPROCK THIS AFTERNOON.
ALTHOUGH AMBIENT WINDS WILL BE LIGHT...THERE IS THE POTENTIAL FOR
ISOLATED HIGH-BASED T-STORMS...WHICH WILL BRING THE THREAT OF DRY
LIGHTNING STRIKES AND STRONG AND ERRATIC DOWNBURST WIND GUSTS ACROSS
THIS AREA.

WARM...DRY AND BREEZY CONDITIONS WILL DEVELOP WEST OF THE DRYLINE ON
WEDNESDAY AFTERNOON...RESULTING IN A PERIOD OF ELEVATED TO BRIEFLY
CRITICAL FIRE WEATHER TO MUCH OF THE CAPROCK. CURRENTLY...IT APPEARS
WINDS WILL BE A LITTLE MARGINAL ON WEDNESDAY THOUGH RH VALUES WILL
LIKELY DIP BELOW 15 PERCENT. THURSDAY WILL BRING MORE WARMTH AND
EVEN DRIER AND WINDIER CONDITIONS FOR MOST OF THE SOUTH PLAINS
REGION...AND A FIRE WEATHER WATCH MAY EVENTUALLY BE NEEDED. A COLD
FRONT MOVING THROUGH EARLY FRIDAY WILL BRING COOLER AIR AND A
TEMPORARY REPRIEVE FROM THE HEIGHTENED FIRE WEATHER CONCERNS.

&&

.PRELIMINARY POINT TEMPS/POPS...
FRIONA        83  47  86  45 /  10  10   0  10
TULIA         84  51  87  48 /  10  10  10  10
PLAINVIEW     85  51  86  48 /  20  10  10  10
LEVELLAND     85  51  87  49 /  20  10  10  10
LUBBOCK       86  53  88  52 /  20  10  10  10
DENVER CITY   83  52  85  50 /  20  10  10  10
BROWNFIELD    84  53  86  50 /  20  20  10  10
CHILDRESS     89  57  89  56 /  20  20  10  10
SPUR          88  56  87  55 /  30  20  10  10
ASPERMONT     89  59  86  63 /  20  30  10  10

&&

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

$$

33/23

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