Area Forecast Discussion
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FXUS64 KLUB 230117
AFDLUB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
817 PM CDT FRI MAY 22 2015

.UPDATE...
MOIST COOL AIRMASS WITH FOG DEVELOPING EARLY THIS EVENING IN THE
SOUTHERN AND CENTRAL SOUTH PLAINS. RAP SHORT TERM SOLUTION
INDICATES GOOD CHANCE THIS WILL EXPAND FURTHER NORTH AND WEST
DURING THE EVENING. UPDATED FOR THE FOG. RMCQUEEN

&&

.PREV DISCUSSION... /ISSUED 650 PM CDT FRI MAY 22 2015/

AVIATION...
LOW CIGS ARE HERE TO STAY THROUGH A MAJORITY OF THIS TAF PERIOD.
IFR TO MVFR CIGS THIS EVENING ARE EXPECTED TO QUICKLY DROP SOLIDLY
INTO IFR AND POSSIBLY LIFR TONIGHT. AN UPPER LEVEL DISTURBANCE
MOVING OVER THE REGION TONIGHT WILL GENERATE WIDESPREAD SHOWERS
AND THUNDERSTORMS DURING THE EARLY MORNING HOURS ON SATURDAY. IF
ANY STORMS DO IMPACT A TAF SITE...THE VISIBILITY WILL LIKELY DROP
FOR A BRIEF TIME BUT LOW CIGS WILL REMAIN. AFTER STORMS CLEAR THE
AREA LATE SATURDAY MORNING OR EARLY AFTERNOON...CIGS WILL
EVENTUALLY RISE INTO MVFR AND POSSIBLY VFR BY THE END OF THIS TAF
PERIOD.

PREV DISCUSSION... /ISSUED 351 PM CDT FRI MAY 22 2015/

SHORT TERM...
.A FLASH FLOOD WATCH IS NOW IN EFFECT FOR THE ENTIRE
AREA...EFFECTIVE FROM MIDNIGHT TONIGHT THROUGH EARLY SATURDAY
AFTERNOON...

AFTER THE EARLY DAY CONVECTION THINGS HAVE BEEN FAIRLY QUIET THIS
AFTERNOON...BUT THE WEATHER WILL SWING BACK TOWARD THE ACTIVE SIDE
LATE TONIGHT. THIS WILL OCCUR AS ANOTHER UPPER LEVEL DISTURBANCE
RAPIDLY APPROACHES FROM THE SOUTHWEST AHEAD OF THE PRIMARY UPPER LOW
MAKING ITS WAY SLOWLY EASTWARD THROUGH THE DESERT SOUTHWEST.
TEMPERATURES HAVE BEEN SLOW TO WARM TODAY WITH CLOUD COVER HOLDING
TOUGH...THOUGH WE HAVE SEEN READINGS EDGING UP INTO THE 60S FOR THE
FIRST TIME IN A WHILE AS SOUTHEASTERLY WINDS AND LIMITED INSOLATION
HAVE PROVIDED SOME MODIFICATION. THE MOIST SOUTHEAST FLOW WILL
STRENGTHEN TONIGHT IN ADVANCE OF THE APPROACHING WAVE...WITH STRONG
MOISTURE ADVECTION AND INCREASING UPPER DIVERGENCE AND LIFT
SUPPORTING THE RISK FOR WIDESPREAD RAIN...SOME WHICH WILL BE
HEAVY...LATE TONIGHT.

INITIALLY...CONVECTION WILL LIKELY DEVELOP IN SOUTHEAST NEW MEXICO
AND SOUTHWEST TEXAS THIS EVENING BEFORE GROWING UPSCALE INTO ONE OR
TWO COMPLEXES AS THEY MOVE NORTHEAST INTO AND ACROSS THE SOUTH
PLAINS REGION SATURDAY MORNING. IT APPEARS THE BULK OF THE ACTIVITY
WILL HOLD OFF LOCALLY UNTIL AROUND OR AFTER MIDNIGHT...WITH HEAVIER
RAIN AFFECTING LOCATIONS ON THE CAPROCK IN THE 06-12Z
TIME-FRAME...THEN SPREADING OFF THE CAPROCK BY 09-12Z. AS
USUAL...THERE ARE DIFFERENCES REGARDING THE PLACEMENT OF THE
HEAVIEST RAIN...WITH SOME NWP SUGGESTING THE NORTHWEST ZONES MOST
FAVORED...WHILE OTHER SOLUTIONS LIKE THE CENTRAL AND EASTERN ZONES.
IT IS TOUGH TO SAY EXACTLY WHERE THE HEAVIEST RAIN WILL FALL...BUT
SOMEONE IN THE AREA WILL LIKELY SEE A QUICK 1-3+ INCHES...WHICH WHEN
FALLING ON TOP OF THE ALREADY SATURATED SOILS...WILL RESULT IN
FLOODING ISSUES. OUTSIDE OF THE HEAVIEST RAIN SWATHS...A SOLID INCH
OF RAIN WILL LIKELY FALL IN MANY SPOTS. THE MOST WIDESPREAD AND
HEAVY RAIN WILL THEN LIKELY SHIFT OFF TO THE EAST BY SATURDAY
AFTERNOON...THOUGH ADDITIONAL REDEVELOPMENT WILL BE POSSIBLE AS THE
WESTERN TROUGH CONTINUES TO PROVIDE LARGE SCALE SUPPORT AND ANOTHER
EMBEDDED DISTURBANCE QUICKLY FOLLOWS ON THE HEELS OF THE EARLIER DAY
WAVE. GIVEN THE GOOD PROSPECTS FOR HEAVY RAIN SOMEWHERE IN THE AREA
AND THE RISK OF FLOODING...WE HAVE DECIDED TO ISSUE A FLASH FLOOD
WATCH FOR THE ENTIRE AREA FROM MIDNIGHT TONIGHT THROUGH EARLY
SATURDAY AFTERNOON. ADDITIONAL FLOOD HEADLINES MAY BE POSSIBLE LATER
SATURDAY...DEPENDING ON HOW THINGS EVOLVE IN THE WAKE OF THE ROUND
OF CONVECTION EARLIER IN THE DAY.

IN ADDITION TO THE FLOOD RISK...INCREASING INSTABILITY AND LIFT MAY
SUPPORT A FEW STRONG/SEVERE STORMS LATE TONIGHT MOVING IN FROM THE
SOUTHWEST. THE PRIMARY RISK WITH THE STRONGEST STORMS WOULD BE LARGE
HAIL. THE SEVERE THREAT MAY REDEVELOP SATURDAY AFTERNOON...BUT THIS
WILL BE CONTINGENT ON HOW THE EARLIER DAY ACTIVITY EVOLVES AND HOW
MUCH HEATING CAN BE REALIZED.

TEMPERATURES WILL BE ON THE MILD SIDE TONIGHT AS MOIST SOUTHEASTERLY
FLOW STRENGTHENS. THE SOUTHERLY WINDS /ALONG WITH AT LEAST SOME
INSOLATION OVER THE WESTERN ZONES/ SHOULD SECURE AFTERNOON HIGHS ON
SATURDAY PEAKING IN THE 70S FOR MOST.

LONG TERM...
THE UPPER-LOW WILL MOVE SLOWLY ACROSS THE ROCKIES LATE SATURDAY
INTO SUNDAY. WITH ANOTHER DISTINCT SHORTWAVE ROTATING AROUND THE
LOW AND PASSING OVER THE AREA SATURDAY NIGHT INTO SUNDAY MORNING
IT IS LIKELY THAT WE WILL SEE AT LEAST SOME T-STORM ACTIVITY
CONTINUING ACROSS THE REGION THROUGH THE NIGHT. A VEERING LOW-LVL
JET SHOULD GUIDE THE ACTIVITY EAST INTO THE ROLLING PLAINS EARLY
SUNDAY MORNING. FOR THE REMAINDER OF SUNDAY...WE/LL LOOK FOR MORE
SUNSHINE AS DEEP-LAYER MOISTURE DECREASES. TEMPERATURES MAY EVEN
REACH 80F IN SOME LOCATIONS. THE MORNING GUIDANCE IS IN GOOD
AGREEMENT THAT A MID-LVL DRY PUNCH WILL WORK INTO THE SOUTH
PLAINS DURING THE DAY AS THE SHORTWAVE TROUGH AXIS PIVOTS INTO
THE PANHANDLES AND NORTH TEXAS. THIS IN TURN MAY HELP TO TIGHTEN
AND PUSH THE DRYLINE EAST...BUT COULD ALSO INCREASE THE POTENTIAL
INSTABILITY IN AREAS THAT RETAIN THE LOW- LEVEL MOISTURE. WE/LL
JUST HAVE TO SEE IF A DRYLINE BULGE DEVELOPS SOMEWHERE NEAR THE
CAPROCK EDGE AS THE MORNING GFS AND NAM RUNS SUGGEST...BUT IF
RECENT HISTORY IS ANY GUIDE...THE DRYLINE WILL LIKELY FAVOR A MORE
WESTWARD POSITION...SO WE/LL BE WATCHING THIS CLOSELY. ISOLATED TO
SCATTERED TSTM DEVELOPMENT IS EXPECTED IN THE VICINITY OF THE
DRYLINE SUNDAY AFTERNOON...LIKELY BRINGING A CHANCE OF SEVERE
WEATHER. LARGE-SCALE SUBSIDENCE FOLLOWING THE WAVE SUNDAY EVENING
SHOULD BRING A QUIET SUNDAY NIGHT AND START TO MEMORIAL DAY.
HOWEVER...THE NEXT SHORTWAVE WILL BE MOVING ACROSS AZ AND NM...AND
THE FORECAST AREA WILL LIKELY ALREADY BEGIN TO FEEL THE LIFT FROM
THIS SYSTEM BY MONDAY AFTERNOON. THIS WAVE MAY BE BETTER TIMED
WITH DIABATIC WARMING TO TAP INTO STRONGER INSTABILITY AND GIVE US
ANOTHER ROUND OF POTENTIALLY SEVERE AFTERNOON AND EVENING
T-STORMS. THE DRYLINE MAY ADVANCE INTO THE CENTRAL SOUTH PLAINS
SUNDAY AFTERNOON PROVIDING THE LOW-LVL FOCUS FOR CONVECTIVE
INITIATION...BUT AGAIN WE AREN/T VERY CONFIDENT IN DRYLINE
FORECASTS AT THIS POINT GIVEN ALL THE SOIL AND SURFACE MOISTURE.

WE MAY GET A CHANCE TO DESOGGIFY SOMEWHAT TUESDAY INTO WEDNESDAY
AS A BRIEF PERIOD OF LOW-AMPLITUDE RIDGING INTERRUPTS OUR SEQUENCE
OF WAVES. HOWEVER...WARMER TEMPS AND PLENTIFUL LOW-LVL MOISTURE
MAY BE SUFFICIENT TO GIN UP SOME DIURNAL CONVECTION EITHER OF
THOSE DAYS...WITH BETTER CHANCES ARRIVING LATE WED AS HEIGHT FALLS
OVERSPREAD THE REGION DOWNSTREAM OF THE NEXT TROUGH MOVING THROUGH
THE WEST. SOLID T-STORM CHANCES WILL LIKELY RESUME WITH THE
PASSAGE OF THIS TROUGH THURSDAY INTO FRIDAY...ALONG WITH A SLIGHT
COOL OFF.

&&

.PRELIMINARY POINT TEMPS/POPS...
FRIONA        56  76  51  76 /  80  50  20  20
TULIA         58  73  55  76 /  80  60  30  30
PLAINVIEW     60  73  57  78 /  80  60  30  30
LEVELLAND     61  77  57  80 /  80  50  30  20
LUBBOCK       62  75  58  80 /  80  60  30  30
DENVER CITY   61  79  56  80 /  80  50  30  20
BROWNFIELD    62  76  58  81 /  80  60  30  20
CHILDRESS     62  74  62  80 /  60  80  40  40
SPUR          62  75  60  80 /  70  80  40  50
ASPERMONT     65  77  62  83 /  50  80  50  50

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH FROM MIDNIGHT CDT TONIGHT THROUGH SATURDAY
AFTERNOON FOR TXZ021>044.

&&

$$

05/99



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