Area Forecast Discussion
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FXUS64 KLUB 200524
AFDLUB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
1224 AM CDT WED MAY 20 2015

.AVIATION...
HIGH CONFIDENCE OF IFR CIGS PREVAILING FOR MOST/IF NOT ALL/ OF
THIS TAF CYCLE. STRONG COLD FRONT IS ON SCHEDULE TO CLEAR LBB
SHORTLY BEFORE 06Z AHEAD OF A SHIELD OF IFR STRATUS AND SOME FOG.

VISBYS HAVE FALLEN TO AS LOW AS 1/2SM AT TIMES BEHIND THE FRONT
AND THIS THREAT SEEMS MOST PRUDENT AT LBB AND PVW WHEREAS NEARBY
SHRA/TSRA AT CDS FOR ANOTHER HOUR SHOULD KEEP THE LOW LEVELS MIXED
TO AVOID POOR VISBYS.

EXTENT OF LOW CIGS AS FAR NORTH AS KANSAS SUGGEST IFR WILL PREVAIL
ALL MORNING AND LIKELY THE AFTERNOON...THOUGH A FEW MODELS
INDICATE CIGS RISING TO MVFR FOR A COUPLE HOURS THIS AFTN BEFORE
RESUMING IFR THEREAFTER.

&&

.PREV DISCUSSION... /ISSUED 914 PM CDT TUE MAY 19 2015/

UPDATE...
UPDATED TO LOWER MIN TEMPS CONSIDERABLY TONIGHT FOR A STRONG COLD
FRONT NOW ENTERING THE FAR SOUTHERN TX PANHANDLE. ABUNDANT
STRATUS AND FOG AS LOW AS 1/2 MILE WAS NOTED BEHIND THIS FRONT AND
THE VISIBILITY AT HEREFORD PLUMMETED FROM 10 MILES TO JUST OVER 1
MILE IN 20 MINUTES. TEMPS IN THE 40S ALREADY ACROSS THE NORTHERN
PANHANDLE CONFIRM THE MAGNITUDE OF COLD ADVECTION...SO HAVE
UPDATED GRIDS LARGELY IN LINE WITH THE LATEST RAP AND HRRR
SOLUTIONS WHICH HAVE A GOOD HANDLE ON THESE TRENDS.

POP-WISE...DROPPED MOST PRECIP MENTION FROM THE CAPROCK
TONIGHT...HOWEVER WE STILL EXPECT SOME STORMS TO RE-DEVELOP WWD
TO NEAR THE I-27 AND HWY 87 CORRIDOR LATER TONIGHT AS THE COLD
FRONT AND TRAILING FRONT ALOFT INTERSECT DEEPER MOISTURE EAST OF
THE RETREATING DRYLINE.

&&

.PREV DISCUSSION... /ISSUED 349 PM CDT TUE MAY 19 2015/

SHORT TERM...
THE MORNING SHOWER AND THUNDER ACTIVITY HAS CLEARED AWAY LEAVING
PLENTY OF SUN TO WARM THE SURFACE. BY MID AFTERNOON WITH RECOVERY
AND WEAK SURFACE PRESSURE FALLS UNDERWAY...SURFACE BASED CAPES HAD
INCREASED TO OVER 3000 JOULES PER KILOGRAM WHILE SURFACE FLOW WAS
MOSTLY SOUTHERLY AND BULK SHEAR VALUES 40+ KNOTS. MOST SHORT RANGE
SOLUTIONS SHOWED SOME DEGREE OF THUNDERSTORM INITIATION WITH THESE
FAVORABLE CONDITIONS LATE THIS AFTERNOON. SEVERAL SHORT CUMULUS
STREETS OVER THE WESTERN SOUTH PLAINS WITHIN A WEAK SURFACE
CONVERGENCE ZONE/DRYLINE...WERE BUBBLING WITH NORTHERN END OF THIS
AREA OVER THE NORTHWESTERN SOUTH PLAINS APPEARING CLOSEST TO
BREAKING OUT ALTHOUGH AS OF YET UNSUCCESSFUL. WITH ABOVE INDICES AND
CURRENT CONDITIONS WE WILL RETAIN A SOLID CHANCE FOR THUNDERSTORMS
AND A POTENTIAL SEVERE THREAT INTO THE EARLY EVENING.

A STATIONARY FRONTAL BOUNDARY ACROSS THE CENTRAL PANHANDLE INTO
WESTERN OKLAHOMA ALSO APPEARS WILL GET SHOVED SOUTHWARD THIS EVENING
AS A SHORT-WAVE UPPER TROUGH ROTATES NORTHWARD THROUGH THE CENTRAL
PLAINS. THIS FRONT MAY LEAD TO MORE ORGANIZED THUNDERSTORMS
SPREADING OUT OF THE PANHANDLE FAVORING NORTH CENTRAL TO NORTHEAST
ZONES...ALTHOUGH SHORT RANGE SOLUTIONS HAVE BEEN TRENDING FURTHER
WEST WITH DEVELOPMENT RECENTLY. AND THIS ACTIVITY WOULD THEN FOLLOW
THE FRONT SOUTHWARD LATER TONIGHT AND EARLY WEDNESDAY...WITH WESTERN
DEVELOPMENT STILL LESS CERTAIN THAN EAST THOUGH ALSO TRENDING MORE
FAVORABLE. BOUNDARY SHOULD MOVE SOUTH OF THE AREA EARLY WEDNESDAY
AND REMAINING THUNDER CHANCES WILL BECOME INCREASINGLY MOST
FAVORABLE SOUTH OF OUR AREA DURING THE DAY WEDNESDAY. TEMPERATURES
HAVE TRENDED SLIGHTLY COOLER FOR MUCH OF THE AREA WEDNESDAY AS WELL.

ANYWAY...WITH SOMEWHAT MARGINAL CONFIDENCE ABOVE IS OUR LATEST
THINKING AND WE HAVE MADE A NUMBER OF ADJUSTMENTS TO MATCH. THE
HEAVY RAIN THREAT MAY REDEVELOP AS WELL OVERNIGHT SHOULD A WELL-
ORGANIZED CONVECTIVE COMPLEX COME TOGETHER BUT SIGNALS TOO MIXED TO
JUMP ALL-IN JUST YET. SO...BE READY FOR POTENTIALLY FAST-BREAKING
WEATHER THROUGH THE NIGHT WITH A BONA-FIDE THOUGH NOT AT ALL CERTAIN
RISK FOR SEVERE STORMS AND STILL AT LEAST LOCALLY HEAVY RAIN
LEADING TO A MINOR FLOODING THREAT. RMCQUEEN

LONG TERM...
THE ACTIVE MAY WEATHER SHOWS NO SIGN OF LETTING UP THROUGH AT LEAST
THIS WEEKEND. THIS WILL OCCUR AS SOME FORM OF SOUTHWESTERLY FLOW
ALOFT PERSISTS OVER WEST TEXAS DOWNSTREAM OF WESTERN CONUS
TROUGHING. THIS UNSETTLED PATTERN WILL PROVIDE MORE OPPORTUNITIES
FOR SEVERE WEATHER AS WELL AS HEAVY RAINFALL.

TO KICK OFF THE EXTENDED...THE SOUTH PLAINS REGION SHOULD FIND
ITSELF NORTH OF A COLD FRONT WITH SURFACE RIDGING AND ABUNDANT CLOUD
COVER PROVIDING COOL AND MOIST CONDITIONS WEDNESDAY NIGHT INTO
THURSDAY. THAT SAID...THERE WILL BE ENOUGH ELEVATED INSTABILITY AND
RETURNING SOUTHEASTERLY FLOW OFF THE DECK THAT ISOLATED TO SCATTERED
SHOWERS/STORMS WILL BE POSSIBLE. A FEW STRONGER ELEVATED STORMS COULD
EVEN OCCUR THOUGH MUTED SURFACE-BASED HEATING/INSTABILITY SHOULD KEEP
THE OVERALL SEVERE THREAT RELATIVELY LOW.

THE COVERAGE AND INTENSITY OF THE CONVECTION MAY TREND UPWARD LATE
THURSDAY INTO EARLY FRIDAY AS A LEAD SHORTWAVE TROUGH IS PROGGED TO
EJECT THROUGH THE SOUTHWEST FLOW OVER THE SOUTHERN HIGH PLAINS.
EVENTUALLY THE WARM FRONT AND WARM SECTOR IS FORECAST TO LIFT NORTH
ACROSS THE AREA OPENING THE DOOR FOR BETTER CHANCES FOR SURFACE-
BASED CONVECTION BY FRIDAY AFTERNOON...THOUGH WHETHER THERE WILL BE
ANY FORCING FOR LARGE-SCALE ASCENT IS UNCLEAR. THAT MAY CHANGE BY
LATE FRIDAY NIGHT INTO EARLY SATURDAY WHEN ANOTHER WEAK UPPER-LEVEL
DISTURBANCE MAY RACE THROUGH THE FLOW. THE WESTERN TROUGH IS THEN
PROGGED TO APPROACH FROM THE WEST ON SATURDAY WITH THE DRYLINE
LIKELY SOMEWHERE NEAR THE TX/NM LINE BY LATE IN THE DAY WHERE IT
WILL PROVIDE A FOCUS FOR CONVECTIVE INITIATION. MODERATE TO STRONG
INSTABILITY AND DEEP-LAYER SHEAR WILL BRING THE RISK FOR SEVERE
STORMS. THIS SAME PATTERN WILL CONTINUE INTO SUNDAY THOUGH THE
DRYLINE AND BEST LARGE-SCALE ASCENT MAY SHIFT EASTWARD A BIT.

A WEAK FRONT MAY SNEAK INTO THE AREA BEHIND THE WEEKEND TROUGH EARLY
MONDAY...BUT IT IS NOT EXPECTED TO HAVE A STRONG PUSH WHICH SHOULD
ALLOW GOOD MOISTURE AND INSTABILITY TO CONTINUE TO RESIDE NEARBY
INTO MUCH OF NEXT WEEK. IT DOES APPEAR THE UPPER FLOW MAY FLATTEN
AND WEAKEN NEXT WEEK...BUT GIVEN THE MAGNITUDE OF THE PROGGED
INSTABILITY AT LEAST ISOLATED LATE DAY STORMS MAY BE POSSIBLE AND
WE HAVE RETAINED SLIGHT CHANCE POPS FROM MONDAY ONWARD.

HIGHS ON THURSDAY WILL ONLY BE IN THE 50S AND 60S...BUT SHOULD
MODERATE INTO THE UPPER 60S TO UPPER 70S FRIDAY BEFORE FURTHER
WARMING INTO THE 70S AND LOWER 80S SATURDAY...WHERE HIGHS WILL
GENERALLY REMAIN THROUGH THE REST OF THE EXTENDED.

&&

.PRELIMINARY POINT TEMPS/POPS...
FRIONA        50  59  49  69 /  30  50  60  40
TULIA         50  58  49  67 /  30  40  70  60
PLAINVIEW     51  59  51  68 /  30  40  70  60
LEVELLAND     52  60  52  72 /  40  60  60  50
LUBBOCK       51  61  52  71 /  40  50  70  60
DENVER CITY   54  61  52  75 /  40  60  60  50
BROWNFIELD    54  61  52  74 /  40  60  60  50
CHILDRESS     53  64  55  71 /  30  20  60  60
SPUR          53  62  53  72 /  40  40  60  60
ASPERMONT     56  65  56  77 /  50  40  60  60

&&

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

$$

93/31



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