Hail and Damaging Winds in Texas, June 7, 2001

DEEP SOUTH TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
315 PM CDT THU JUN 7 2001

SHORT TERM...INTERESTING SCENARIO WITH REMNANTS OF TROPICAL
DEPRESSION ALLISON OVER EAST TEXAS. FIRST OF ALL...SUBSIDENT AIR
CURRENTLY OVER DEEP SOUTH TEXAS WITH LIGHT NORTHWEST FLOW ALOFT.
WEAK PRESSURE GRADIENT OVER THE SURFACE PRODUCING LIGHT WINDS IN
ADDITION ALLOWING TEMPS TO TIE RECORD NUMBERS AT KBRO THIS
AFTERNOON. SECOND...DEFORMATION ZONE HAS DEVELOPED OVER THE RIO
GRANDE PLAINS WITH A CYCLONIC VORTICITY CENTER ROTATING ON WEST SIDE
OF UPPER FEATURE ASSOC W/ALLISON. ABUNDANT MOISTURE WITH EXTREMELY
HIGH CAPES AND LI'S AS MAX HEATING PEAKS WARRANT POSSIBILITY OF
SEVERE STORMS CENTRAL AND WEST WITH DAMAGING WINDS AND HEAVY
RAINFALL POSSIBLE PER LATEST SPC MESO DISC. IN ADDITION...SEABREEZE
TO BE ADDITIONAL FACTOR FOR LOW LEVEL CONVERGENCE. AS FOR
ALLISON...THE COL BETWEEN THE UPPER RIDGE OVER THE SOUTHWEST U.S.
AND THE RIDGE OVER THE SOUTHEAST U.S. IS PROVIDING WEAK STEERING
CURRENTS. LESS DRY AIR ENTRAINMENT IN SOUTHERN FLANK PROVIDING
ADDITIONAL CONVECTION ALONG UPPER TX COAST. ALL 12Z MODELS
CONSISTENT WITH SOUTHWEST DRIFT AS UPPER RIDGE OVER THE SOUTHWEST
U.S. AMPLIFIES SOMEWHAT AND EDGES INTO THE SOUTHERN PLAINS. TIMING
AND MOVEMENT SEEMS TO BE A CHALLENGE WITH ALLISON BEING OVER THE
COASTAL BEND FRIDAY MORNING...AND EDGING INTO THE CWA FRIDAY
AFTERNOON. AS UPPER LOW DRIFTS SW...UPPER LEVEL DIFFLUENCE FAVORABLE
FOR ADDITIONAL TSTM DEVELOPMENT. BIG QUESTION IS IF ALLISON
CONTINUES TO MAINTAIN TROPICAL CHARACTERISTICS AS IT TAPS MOISTURE
FROM GULF AND HOW FAR SOUTH THE PERIPHERY INFLUENCES CLOUD COVER AND
CONVECTION. WILL GO WITH INCREASING POPS FOR NOW WITH INCREASING
CLOUD COVER LOWERING MAX TEMPS.

EXTENDED...12Z AVN MODEL RUN CONTINUES TO BRING REMNANTS OF ALLISON
OVER DEEP SOUTH TEXAS THIS WEEKEND. IT APPEARS UPPER RIDGE TO THE
WEST AND NORTH TRAPS ALLISON OVER THE LOWER TEXAS COAST. IF THIS
PANS OUT...THE POTENTIAL FOR MORE RAIN...POSSIBLY HEAVY WITH
INCREASING TROPICAL MOISTURE...WILL WARRANT CONTINUED CHANCE OF
CONVECTION IN THE FORECAST.

MARINE...CURRENT BUOY OBS REFLECT 4 TO 5 FOOT WAVES WITH LIGHT
SOUTHWEST WIND BACKING TO SOUTHEAST. WINDS AND SEAS TO BE INFLUENCED
BY MOVEMENT OF THE REMNANTS OF ALLISON. NO FLAGS WARRANTED AT THIS
TIME...HOWEVER INFLUENCES FROM ALLISON MAY WARRANT SCEC TONIGHT IF
SWELLS INCREASE OFFSHORE. CONVECTION TO INCREASE IN TIME AS LOWER
LEVEL LOW DRIFTS SW ALONG THE COAST. WINDS AND SEAS LIKELY TO
INCREASE WITH THE LOW OVER DEEP SOUTH TX LATE WEEKEND INTO EARLY
NEXT WEEK. ALSO...WILL NEED TO MONITOR THE REMOTE POSSIBILITY OF
ALLISON EMERGING INTO THE GULF.

SYNOPTIC-PUBLIC...MC.61/AVIATION-MARINE...KN.57
MESO...MARTINEZ

PRELIMS:
BRO BE 077/093 076/090 075  20/30/20/40/30
HRL BE 076/095 075/092 074  20/30/20/40/30
MRFE BE 077/097 076/094 075  30/30/20/40/30
RGC BE 076/098 075/095 074  30/30/20/40/30
SPI BE 078/085 077/084 076  20/30/20/40/30

INTERNET ADDRESS...WWW.SRH.NOAA.GOV/BRO

.BRO...NONE.

TXZ248-252-253-080100-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BROWNSVILLE TX
217 PM CDT THU JUN 7 2001

...A FEW SEVERE THUNDERSTORMS MAY BE POSSIBLE LATE THIS AFTERNOON
AND EVENING...

THE ATMOSPHERE REMAINS MOIST AND UNSTABLE ACROSS DEEP SOUTH TEXAS
THIS AFTERNOON. BY LATE THIS AFTERNOON...AN UPPER LEVEL DISTURBANCE
WILL MOVE SOUTH TOWARDS THE LOWER RIO GRANDE VALLEY. AS THIS
DISTURBANCE INTERACTS WITH A WEAK BOUNDARY ACROSS BROOKS AND JIM
HOGG COUNTIES...A FEW SEVERE THUNDERSTORMS MAY DEVELOP.

AT THIS TIME...IT APPEARS THAT THE GREATEST THREAT FOR SEVERE
THUNDERSTORMS WILL BE OVER WESTERN SECTIONS OF DEEP SOUTH TEXAS
AFTER 4 PM...MAINLY WEST OF HIGHWAY 77. THE PRIMARY THREAT WILL BE
HEAVY RAIN AND DAMAGING WINDS...HOWEVER HAIL WILL BE POSSIBLE WITH
THE STRONGEST STORMS.

EAST OF HIGHWAY 77...ISOLATED SHOWERS AND THUNDERSTORMS MAY DEVELOP
ALONG THE SEA BREEZE. SOME OF THE STRONGER STORMS MAY APPROACH
SEVERE LIMITS. HOWEVER...HEAVY RAINFALL WILL BE THE PRIMARY THREAT
WITH THESE STORMS.

RESIDENTS ACROSS WESTERN AND CENTRAL PORTIONS OF DEEP SOUTH
TEXAS...INCLUDING ZAPATA...JIM HOGG...BROOKS...STARR...AND HIDALGO
COUNTIES SHOULD CLOSELY MONITOR THIS DEVELOPING WEATHER SITUATION.

CASTILLO/MCGUIRE