Hail in Texas, February 27, 2001

WEST CENTRAL TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
ISSUED BY NWS MIDLAND TX
350 PM CST TUE FEB 27 2001

PROBLEMATIC FORECAST THIS AFTERNOON WITH A VERITABLE PLETHORA OF
WEATHER SITUATIONS THROUGH THE NEXT 24 HOURS.  AFTER HANGING UP
ALONG THE RED RIVER COUNTIES EARLIER THIS MORNING...THE ARCTIC
FRONT HAS SAGGED SOUTH TO NEAR A BIG SPRING...BLACKWELL...TO CROSS
PLAINS LINE.  TO THE SOUTH OF THIS BOUNDARY...THE AIRMASS IS
MODERATELY UNSTABLE WITH SURFACE DEWPOINTS AOA 60 DEGREES F AND
MUCAPES IN THE 2000 TO 2500 J/KG RANGE.  KINEMATIC PARAMETERS ARE
SOMEWHAT WEAKER...WITH MODEST LOW LEVEL CONVERGENCE AND BRN SHEARS
ON THE BUBBLE.  CONVECTION HAS BEEN SLOW TO FIRE ACROSS THE SJT CWFA
THIS AFTERNOON...POSSIBLY BECAUSE OF SHORTWAVE RIDGING BETWEEN A
SHEARING OUT SYSTEM OVER THE MIDWESTERN STATES AND THE CLOSED UPPER
LOW OVER SOUTHERN CALIFORNIA.  NEVERTHELESS...WE FEEL CONFIDENT IN
CONVECTIVE CHANCES INCREASING LATE THIS AFTERNOON THROUGH THE
EVENING HOURS.  GIVEN THE FORECAST MOVEMENT OF THE COLD FRONT...
WE EXPECT MUCH OF THE CONVECTION WILL BE ELEVATED BY MID EVENING...
THEREBY LIMITING THE SEVERE THREAT TO LARGE HAIL.  WE WILL MAINTAIN
MENTION OF SEVERE IN THE ZONES THROUGH THE EVENING HOURS GENERALLY
ALONG AND SOUTH OF THE PRESENT FRONTAL POSITION.

THE FOCUS NOW SHIFTS TO HEAVY RAIN AND THE POTENTIAL FOR SIGNIFICANT
ICING.  AS STATED BY THE PMDHMD...THE ETA AND AVN DO NOT APPEAR TO
CAPTURE THE SUBTLE FEATURES EMBEDDED IN THE SOUTHWESTERLY FLOW ALOFT.
NEVERTHELESS...THESE MODELS ARE CONSISTENT IN DEVELOPING A STRONG
MOIST ISENTROPIC UPGLIDE EVENT OVER THE SJT CWFA OVERNIGHT.  GIVEN
FORECAST PRECIP WATER VALUES NEAR 1 IN...THERE IS A THREAT OF HEAVY
RAINFALL OVER MAINLY THE SOUTHEASTERN THIRD OF THE CWFA.  THE ETA
QPFS BEAR THAT OUT...WITH UPWARDS OF 1 TO 1.5 INCHES OF RAIN
FORECAST FOR THE CONCHO VALLEY THROUGH TOMORROW MORNING.  ANTECEDENT
PRECIPITATION OVER THESE AREAS...HOWEVER...IS LACKING...AND WE WILL
HOLD OFF ON ANY TYPE OF FLASH FLOOD WATCHES AT THIS TIME.  WE WILL
CONTINUE TO MONITOR THIS SITUATION.

THE ARCTIC AIR WILL CONTINUE TO FLOW INTO THE CWFA OVERNIGHT...AND
TEMPERATURES ARE FORECAST TO REACH THE FREEZING MARK ALONG AND NORTH
OF I-20 BY DAYBREAK WEDNESDAY.  MESOETA SOUNDINGS IN THESE AREAS
SUGGEST A FORMIDABLE FREEZING RAIN THREAT...AND THIS IS REFLECTED IN
THE QPFHSD DISCUSSION FROM NCEP.  BECAUSE THE FREEZING RAIN THREAT
WILL OCCUR CLOSE TO DAYBREAK WEDNESDAY...WE WILL ISSUE A WINTER STORM
WATCH NOW AND ANTICIPATE AN ADVISORY OR WARNING WITH THE NEXT ZONE
FORECAST ISSUANCE.

AFTER ALL THIS...THINGS QUIET DOWN A BIT.  TEMPERATURES WILL REBOUND
ABOVE THE FREEZING MARK OVER NORTHERN ZONES DURING THE AFTERNOON
HOURS.  RAIN SHOULD END FROM WEST TO EAST DURING THE AFTERNOON HOURS
AS WELL AS THE MOIST UPGLIDE RELAXES SOMEWHAT.  RAIN CHANCES WILL
INCREASE THURSDAY AS UPGLIDE RENEWS IN ADVANCE OF THE APPROACHING
CALIFORNIAN UPPER LOW.  BY THIS TIME...THE BULK OF THE ARCTIC AIR
WILL HAVE SHIFTED NORTHEAST...AND THE PRECIPITATION FORECAST LOOKS
LIQUID AT THIS TIME.  REGARDING TEMPERATURES...WILL SHADE NUMBERS
CLOSER TO THE COOLER AVN GUIDANCE GIVEN CONDITIONS BEHIND THE FRONT.

IN THE EXTENDED...HAVE PRETTY MUCH BOUGHT OFF ON THE NCEP SCENARIO
WITH THE EJECTING CALIFORNIAN UPPER LOW.  THUS RAIN LOOKS A GOOD BET
ACROSS MUCH OF THE CWFA THROUGH SUNDAY...WITH WARMER AND DRIER
CONDITIONS EXPECTED THROUGH EARLY NEXT WEEK.

THATS A WRAP...THANKS FOR COORD LBB...MAF...SJT...OUN...FTW...AND
WGRFC.  BLOCKED SHOTS FOLLOW...70.

THE PRELIMINARY GUIDANCE BELOW IS FOR COORDINATION PURPOSES ONLY.
OFFICIAL FORECASTS ARE CONTAINED WITHIN THE WEST CENTRAL TEXAS ZONE
FORECAST.

ABI  34/40/32/48    8712
SJT  39/44/36/52    8712
JCT  44/40/42/56    +712

.SJT...WINTER STORM WATCH IN EFFECT WEDNESDAY FOR CALLAHAN...
       FISHER...HASKELL...JONES...NOLAN...SHACKELFORD...TAYLOR...AND
       THROCKMORTON COUNTIES...TXZ049-054-098-099-113-114-127-128

TXZ049-054-064>066-071>073-076>078-098-099-113-114-127-128-139-140-
154-155-168>170-280300-

WEST CENTRAL TEXAS THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE SAN ANGELO TX
ISSUED BY NWS MIDLAND TX
1208 PM CST TUE FEB 27 2001

...SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF WEST CENTRAL
TEXAS THIS AFTERNOON AND EVENING...

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
TONIGHT ACROSS MUCH OF WEST CENTRAL TEXAS.  THE SLIGHT RISK AREA IS
FOR THAT PART OF WEST CENTRAL TEXAS ALONG AND SOUTH OF A ROBY TO
ALBANY LINE...AND INCLUDES THE CITIES OF ABILENE...BRADY...COLEMAN...
JUNCTION...MASON...OZONA...SAN ANGELO...AND SWEETWATER.  THE PRIMARY
SEVERE WEATHER THREATS ARE LARGE HAIL AND DAMAGING STRAIGHT LINE
WINDS.

AT MIDDAY...A COLD FRONT EXTENDED FROM NEAR WICHITA FALLS SOUTHWEST
TO BETWEEN LUBBOCK AND MIDLAND.  TO THE SOUTH OF THIS FRONT...WARM
AND UNSTABLE AIR FROM THE GULF OF MEXICO COVERED MUCH OF WEST CENTRAL
TEXAS.  THE COLD FRONT WILL MOVE SOUTH INTO THE BIG COUNTRY THIS
AFTERNOON...INTO THE CONCHO VALLEY AROUND SUNSET...AND TO THE I-10
CORRIDOR BY MID EVENING.  ALONG AND AHEAD OF THIS FRONT...SCATTERED
THUNDERSTORMS WILL DEVELOP...AND A FEW OF THESE STORMS MAY BE
SEVERE...AND WILL BE CAPABLE OF PRODUCING LARGE HAIL AND DAMAGING
STRAIGHT LINE WINDS.  VERY HEAVY RAIN AND DEADLY LIGHTNING WILL ALSO
BE POSSIBLE.

THE THREAT OF SEVERE THUNDERSTORM ACTIVITY SHOULD DIMINISH FROM NORTH
TO SOUTH THIS EVENING WITH PASSAGE OF THE COLD FRONT.  THUNDERSTORMS
MAY CONTINUE THROUGH THE EARLY MORNING HOURS WEDNESDAY...HOWEVER...AS
THE COLD AIR BEHIND THE FRONT IS EXPECTED TO BE SHALLOW AND THE
AIRMASS ABOVE THIS LAYER OF COLD AIR WILL BE UNSTABLE.  THE THREAT OF
SEVERE WEATHER AFTER COLD FRONTAL PASSAGE...HOWEVER...APPEARS LOW AT
THIS TIME.

SPOTTER ACTIVATION MAY BE REQUESTED THIS AFTERNOON AND EVENING ALONG
AND SOUTH OF A ROBY TO ALBANY LINE.

THIS OUTLOOK WILL RESUME SCHEDULED ISSUANCE ON MARCH 15 2001.
HOWEVER...THIS OUTLOOK WILL BE ISSUED AS NEEDED WHEN THUNDERSTORMS
THREATEN WEST CENTRAL TEXAS.

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