Area Forecast Discussion
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FXUS64 KLUB 041159
AFDLUB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
659 AM CDT MON MAY 4 2015

.AVIATION...
LOW-LEVEL MOISTURE CONTINUES TO ADVECT NORTHWARD INTO THE AREA
EARLY THIS MORNING AND POCKETS OF LOW CLOUDS HAVE RECENTLY BEEN
DEVELOPING LOCALLY. KPVW WAS ALREADY REPORTING CEILINGS NEAR 3000
FT...AND BOTH KLBB AND KPVW WILL LIKELY SEE A STINT OF MVFR CIGS
LATER THIS MORNING...AND KCDS COULD ALSO EXPERIENCE THE LOWER
CEILINGS TOO. THE CLOUDS SHOULD SCATTERED/LIFT BY LATE MORNING OR
EARLY AFTERNOON...BUT THIS WILL LEAD TO DESTABILIZATION AND THE
PROSPECTS FOR SCATTERED CONVECTION AT THE TERMINALS. KLBB AND KPVW
APPEARED MOST FAVORED FOR AFTERNOON CONVECTION...THOUGH KCDS COULD
SEE THUNDER TOO. CONVECTION IS THEN EXPECTED TO INCREASE IN
COVERAGE TONIGHT...WITH THE PROSPECTS FOR HEAVY RAIN OVERNIGHT.
LOW VISIBILITIES AND LOW CIGS WILL BE POSSIBLE AT THE TERMINALS
WITH THE HEAVIEST STORMS OVERNIGHT. OUTSIDE OF ANY CONVECTIVE WIND
GUSTS...SOUTHERLY WINDS WILL PREVAIL MUCH OF TODAY AND TONIGHT.

&&

.PREV DISCUSSION... /ISSUED 421 AM CDT MON MAY 4 2015/

SHORT TERM...
..THE THREAT FOR LOCALLY HEAVY RAINFALL STILL APPEARS ON TRACK FOR
LATE TODAY INTO TONIGHT AND A FLASH FLOOD WATCH HAS BEEN ISSUED
FOR MUCH OF THE WESTERN AND CENTRAL SOUTH PLAINS...

THE ATMOSPHERE TRENDED MORE ACTIVE YESTERDAY AS A MODEST INCREASE IN
MOISTURE TEAMED WITH DEVELOPING SOUTHWESTERLY FLOW ALOFT. THIS
PATTERN WILL CONTINUE TODAY...BUT IT WILL BE SUPPLEMENTED BY BETTER
MOISTURE AND INSTABILITY ALONG WITH INCREASINGLY DIFFLUENT UPPER
FLOW. EARLY THIS MORNING WE WERE STILL SEEING SCATTERED SHOWERS AND
EVEN A FEW ISOLATED STORMS ROAMING THE PANHANDLES BACK INTO NEW
MEXICO AND FROM THE PECOS RIVER VALLEY INTO FAR WEST TEXAS. IN
ADDITION...08Z OBSERVATIONS SHOWED THAT 60+ DEWPOINT AIR WAS SURGING
NORTHWARD THROUGH THE EDWARDS PLATEAU...WITH LOW TO MID-50 DEWPOINTS
NOW IN PLACE ACROSS MUCH OF THE CWA. THIS ADDED MOISTURE WILL BE
ACTED UPON BY SEVERAL WEAK MID-LEVEL DISTURBANCES EMBEDDED IN THE
SOUTHWESTERLY FLOW AHEAD OF AN UPPER LOW THAT WILL MOVE FROM THE
EASTERN PACIFIC INTO THE DESERT SOUTHWEST OVER THE NEXT 24 HOURS.
ALTHOUGH SOME OF THE DETAILS REMAIN ELUSIVE...THIS PATTERN SHOULD
SET THE STAGE INCREASING SHOWER/STORM TODAY INTO TONIGHT...WITH THE
THREAT FOR HEAVY RAIN PEAKING OVERNIGHT.

LOW CLOUDS ASSOCIATED WITH THE DEEPER MOISTURE ACROSS THE EDWARDS
PLATEAU SHOULD MOVE IN FROM THE SOUTH AROUND DAWN AND SPREAD ACROSS
A GOOD CHUNK OF THE CWA BEFORE SCATTERING OUT. THIS MOISTURE
ADVECTION COUPLED WITH A WEAK PERTURBATION IN THE FLOW ALOFT MAY BE
ENOUGH FOR ISOLATED TO SCATTERED CONVECTION TO DEVELOP LATER THIS
MORNING OR EARLY THIS AFTERNOON AS CAPPING IS FORECAST TO QUICKLY
ERODE. CONVECTIVE COVERAGE SHOULD FURTHER INCREASE THROUGH THE LATE
AFTERNOON AS HEATING AND INSTABILITY PEAK AND INHIBITION ARE
MINIMIZED. DEPENDING ON HOW MUCH HEATING WE CAN GET...MUCAPES COULD
APPROACH OR EXCEED 1500 J/KG IN SPOTS...THOUGH DEEP LAYER SHEAR
SHOULD REMAIN ON THE TAME SIDE. STILL...THIS INSTABILITY COULD
SUPPORT A FEW STRONG/SEVERE STORMS JUST ABOUT ANYWHERE THIS
AFTERNOON AND EVENING. A SOMEWHAT GREATER ORGANIZED SEVERE STORM
THREAT MAY EVOLVE IN EASTERN NEW MEXICO INTO OUR WESTERN ZONES LATE
TODAY AS THE SUB-TROPICAL JET IMPINGES ON THE AREA AND EFFECTIVELY
RAISES THE DEEP LAYER SHEAR. ALSO...WITH PWATS CLIMBING ABOVE 1
INCH...PRECIPITATION EFFICIENT WILL INCREASE ALONG WITH THE THREAT
OF LOCALLY HEAVY DOWNPOURS.

THE CONVECTION IN EASTERN NEW MEXICO IS EXPECTED TO GROW UPSCALE
INTO ONE OR MORE COMPLEXES TONIGHT...WITH THIS ACTIVITY PROPAGATING
EAST OR NORTHEAST. THIS ACTIVITY WILL BE MET BY A STRENGTHENING LLJ
AND PWATS CLIMBING TO AROUND 1.30 INCHES WHILE THE UPPER LEVELS
BECOME INCREASINGLY DIFFLUENT. THIS SHOULD SET THE STAGE FOR
WIDESPREAD RAINFALL. IT APPEARS 1 TO 2 INCH AMOUNTS SHOULD BE COMMON
ACROSS MUCH OF THE CAPROCK WITH LOCALIZED 3-5 INCH TOTALS. THERE
REMAIN SOME QUESTION MARKS WHERE THE HEAVIEST RAIN WILL
FALL...ANYWHERE FROM THE WESTERN TEXAS PANHANDLE INTO THE SOUTHERN
SOUTH PLAINS OR NORTHERN PERMIAN BASIN. GIVEN THIS...WE HAVE DECIDED
TO ISSUE A FLASH FLOOD WATCH FOR OUR WESTERN THREE COLUMNS OF
COUNTIES VALID FROM 21Z THIS AFTERNOON UNTIL 12Z TUESDAY. DEPENDING
ON HOW THINGS EVOLVE LATER TODAY AND TONIGHT THE WATCH MAY NEED TO
BE RECONFIGURED AND/OR EXPANDED IN TIME.

OTHERWISE...TEMPERATURES TODAY WILL BE COOLER WITH MORE CLOUDS AND
MOISTURE IN THE AREA THAN WE HAVE SEEN RECENTLY. HIGHS WILL LIKELY
BE MOSTLY IN THE MIDDLE AND UPPER 70S...THOUGH A FEW LOWER 80S WILL
BE POSSIBLE OFF THE CAPROCK. LOWS TONIGHT SHOULD BE IN THE UPPER 50S
AND LOWER 60S FOR MOST SPOTS.

LONG TERM...
TUESDAY PRESENTS AN INTERESTING FORECAST. IN GENERAL...WE EXPECT A
LARGE AREA OF SHOWERS AND T-STORMS TO BE SLOWLY MOVING NE ACROSS
MUCH OF THE FORECAST AREA EARLY TUESDAY MORNING...WITH THE THREAT
OF HEAVY RAINFALL GRADUALLY SHIFTING INTO THE FAR SRN TX PANHANDLE
AND PERHAPS PORTIONS OF THE ROLLING PLAINS. THE DEGREE OF CLEARING
AND HEATING BACK TO THE SOUTH AND WEST DURING THE DAY REMAINS
UNCLEAR AT THIS TIME. HOWEVER...WITH AMPLE LARGE-SCALE ASCENT
ARRIVING DURING THE AFTERNOON HOURS AS THE UPPER TROUGH SWINGS
ACROSS WEST TEXAS...IT WILL NOT TAKE MUCH DESTABILIZATION TO
REKINDLE T-STORM DEVELOPMENT. IN ADDITION...THE LATEST MODEL
TRENDS HAVE BEEN TO NUDGE THE DRYLINE INTO OUR WRN ZONES...WHICH
WILL PROVIDE A LOW-LVL FOCUS FOR CONVECTIVE INITIATION. DEEP-
LAYER SHEAR WILL BE ON THE ORDER OF 35-45 KTS AND IF THERE IS
SUFFICIENT CAPE...THE RESULTING STORMS WILL LIKELY BRING A SEVERE
WEATHER THREAT AND WE COULD SEE A FEW SUPERCELLS. DEEP MOISTURE
RESIDING EAST OF THE DRYLINE WILL ALSO SUPPORT A HEAVY RAIN
THREAT...BUT LIKELY A MORE LOCALIZED ONE THAN MONDAY NIGHT AND
TUESDAY MORNING. STORM ACTIVITY TUESDAY NIGHT INTO WEDNESDAY
MORNING SHOULD BE CONFINED TO THE ROLLING PLAINS.

WEDNESDAY WILL SEE A BRIEF RETURN OF WEAK UPPER-LEVEL RIDGING IN
THE WAKE OF THE DEPARTING WAVE. HOWEVER...THE LOW-LEVEL WIND
FIELDS WILL QUICKLY RETURN TO A S-SE FETCH AND THE DRYLINE WILL
BEGIN TO RETREAT BACK TO THE NW...LIKELY TAKING ON A SW-NE
ORIENTATION BISECTING THE CWA LATE WED AFTN AND EVENING. T-STORM
INITIATION ALONG THE DRYLINE IS UNCERTAIN AT THIS POINT...AS
RENEWED LIFT MAY BE DELAYED UNTIL WELL AFTER PEAK HEATING. WE
WILL MAINTAIN LOW-END CHANCE POPS UNTIL THE SITUATION BECOMES
MORE CLEAR.

MEDIUM-RANGE GUIDANCE IS IN GOOD AGREEMENT THAT WE WILL SEE AN
ACTIVE PERIOD OF T-STORM ACTIVITY THU AND FRI WITH A LARGE UPPER-
LEVEL STORM SYSTEM MOVING THROUGH THE INTER-MOUNTAIN REGION
MAINTAINING SW FLOW ALOFT WITH LOWERED HEIGHTS AND STEEP MID-LEVEL
LAPSE RATES...AND RICH LOW-LEVEL MOISTURE ALONG AND TO THE EAST OF
THE DRYLINE WHICH SHOULD SLOSH ACROSS THE CWA EACH DAY. AS THE
STORM STORM BEGINS TO CROSS THE ROCKIES ON SATURDAY AND THE MID-
LVL FLOW BEGINS TO VEER IT IS UNCERTAIN WHETHER OR NOT MOISTURE
WILL BE RETAINED ACROSS THE AREA...BUT THE TREND THIS SPRING HAS
BEEN FOR MOISTURE TO HANG ON FARTHER WEST THAN MID-RANGE
PROJECTIONS AND WE WILL KEEP A CHANCE OF T-STORMS GOING ACROSS THE
EASTERN ZONES SAT AFTN AND EVENING. SUNDAY MAY SEE A COLD FRONT
DROP THROUGH THE AREA.

&&

.PRELIMINARY POINT TEMPS/POPS...
FRIONA        74  54  70  50 /  60  90  70  40
TULIA         76  56  68  55 /  40  90  80  60
PLAINVIEW     75  57  70  56 /  40  90  70  60
LEVELLAND     76  58  73  56 /  50  90  60  40
LUBBOCK       77  59  72  58 /  40  80  70  50
DENVER CITY   76  58  76  56 /  50  90  50  30
BROWNFIELD    77  58  75  57 /  40  90  60  40
CHILDRESS     82  62  72  61 /  20  70  70  70
SPUR          79  59  71  59 /  30  70  70  50
ASPERMONT     82  61  74  63 /  20  50  70  60

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH FROM 4 PM CDT THIS AFTERNOON THROUGH TUESDAY
MORNING FOR TXZ021>023-027>029-033>035-039>041.

&&

$$

23/33/23


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