Tornadoes and Hail in Texas, May 25 to 26, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
715 PM CDT WED MAY 25 2011

.AVIATION...
IN A SORT OF HOLDING PATTERN WITH 00Z TAFS AS INGREDIENTS SEEM TO
BE STILL COMING TOGETHER FOR SOME POSSIBLE CONVECTION IN THE NEXT
FEW HOURS. A WEAK SFC BOUNDARY COMBINED WITH ABUNDANT HEATING/LOW
LEVEL MOISTURE/STRONG INFLOW ARE KEY ELEMENTS THUS FAR. BUT NOT A
WHOLE LOT POPPING UP AS OF YET. THE SLOW SWD PUSH OF THE BOUNDARY
SHOULD KEEP A SLIGHT CHANCE OF CONVECTION IN THE FCST THROUGH THE
EVENING HOURS BEFORE THINGS STABILIZE OVERNIGHT. BUT FOR NOW HAVE
KEPT THE MENTION OF CB/VCTS OUT. THE LIGHTER WINDS AND MOSTLY CLR
SKIES OVERNIGHT COULD MAKE FOR SOME BRIEF MVFR/IFR CIGS/VIS AHEAD
OF THE VERY WEAK FRONT...BUT THE DRIER AIR MOVING DOWN INTO SE TX
WILL HELP TO MIX THINGS OUT BY SUNRISE. VFR TO PREVAIL TOMORROW.
41

&&

.PREV DISCUSSION... /ISSUED 257 PM CDT WED MAY 25 2011/
A FRONTAL BOUNDARY FROM WACO TO TEXARKANA AT 19Z SHOULD SLOWLY
SLIDE INTO SE TX LATER THIS EVENING AND TONIGHT. IT IS POSSIBLE
FOR A FEW ISOLATED STORMS TO DEVELOP SHOULD THE CAP WEAKEN ENOUGH
ALONG THE FRONT. SHOULD A STORM DEVELOP...IT WILL LIKELY BECOME
SEVERE GIVEN CAPE OF 3000-3500 J/KG OVER THE AREA. LARGE HAIL AND
DAMAGING STRAIGHT LINE WINDS WILL BE THE MAIN THREATS. AN 18Z
SOUNDING FROM SHV SHOWS A VERY WEAK CAP TO THE NORTH SO THINK THE
MAIN THREAT WILL STILL BE WELL NE OF THE CWA. ANY THUNDERSTORM
ACTIVITY SHOULD BEGIN TO DECREASE BETWEEN 03Z-06Z TONIGHT. THE
FORECAST HAS 20/30 POPS FOR THE NORTHERN PORTIONS OF SE TX AND SEE
NO REASON TO CHANGE THIS ALTHOUGH MORE THAN LIKELY THE CAP WILL
HOLD OVER SE TX.

MODELS ARE ALL IN PRETTY GOOD AGREEMENT WITH BRINGING THE FRONT
INTO SE TX AND STALLING IT ACROSS HOUSTON. GFS HAS THE FRONT
REACHING THE COAST BUT HIGHLY DOUBT THAT. FORECAST STICKS CLOSER
TO THE NAM/WRF SOLUTIONS. DRIER AIR BEHIND THE FRONT MAY BE
ENOUGH FOR COOLING AND MIN TEMPS IN THE UPPER 60S. THIS WILL BE
SHORT LIVED BECAUSE THE FRONT SHOULD LIFT NORTH/DISSIPATE
TOMORROW NIGHT BRINGING BACK THE GULF MOISTURE AND HUMIDITY.

MEMORIAL DAY WEEKEND THROUGH EARLY NEXT WEEK...PERSISTENCE LOOKS
LIKE THE BEST FORECAST. SOUTHERLY FLOW IN THE BOUNDARY LAYER
SHOULD CONTINUE THROUGH THE WEEKEND AND EARLY NEXT WEEK. THE JET
STREAM PATTERN DOES CHANGE BE SUNDAY WITH A DEEPENING TROUGH OVER
THE GREAT BASIN AND A BROAD UPPER LEVEL RIDGE OVER THE N GULF
COAST. THIS RIDGE SHOULD EXPAND INTO TX BY NEXT MON/TUE.
SUBSIDENCE FROM THE RIDGE WILL KEEP THUNDERSTORM CHANCES OUT OF
THE FORECAST WITH MORE HOT/HUMID DAYS. BOTTOM LINE...NO RELIEF
FROM THE DROUGHT FOR THE NEXT WEEK.

39

MARINE...
THE MODERATE TO STRONG ONSHORE FLOW WILL PERSIST FOR THE REST OF
THE AFTERNOON...AND CAUTION FLAGS WILL REMAIN UP FOR ALL WATERS.
WIND SPEEDS AND SEAS WILL DECREASE SIGNIFICANTLY TONIGHT AND
TOMORROW AS A WEAK COLD FRONT MOVES INTO SOUTHEAST TEXAS AND
STALLS NORTH OF THE COAST. THE PRESSURE GRADIENT TIGHTENS AGAIN
ON FRIDAY IN RESPONSE TO ANOTHER AREA OF LOW PRESSURE DEVELOPING
OVER THE SOUTHERN PLAINS. AS A RESULT...A MODERATE TO STRONG
ONSHORE FLOW CAN BE EXPECTED FRIDAY AFTERNOON THROUGH MONDAY
NIGHT...AND CAUTION FLAGS AND/OR ADVISORIES ARE EXPECTED. A
WEAKER EASTERLY FLOW IS EXPECTED BEGINNING AROUND THE MIDDLE OF
NEXT WEEK. 42

CLIMATE...
IF NO RAIN FALLS AT OUR MAJOR CLIMATE SITES FOR THE REST OF
MAY... IAH'S MONTHLY RAINFALL TOTAL OF 0.32 INCHES WOULD RANK AS
THE 6TH DRIEST MAY ON RECORD...HOU'S MONTHLY RAINFALL TOTAL OF
0.19 INCHES WOULD RANK AS THE 4TH DRIEST MAY ON RECORD...GLS'S
MONTHLY RAINFALL TOTAL OF 0.38 INCHES WOULD NOT RANK AS ONE OF
THE TOP 10 DRIEST MAYS ON RECORD...AND CLL'S MONTHLY RAINFALL
TOTAL OF 3.37 INCHES WOULD NOT RANK AS ONE OF THE TOP 10 DRIEST
MAYS ON RECORD. 42

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      66  92  71  95  73 /  30  10  10  10  10
HOUSTON (IAH)              74  94  72  94  74 /  20  10  10  10  10
GALVESTON (GLS)            78  86  76  86  77 /  10  10  10  10  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
303 PM CDT WED MAY 25 2011

TXZ163-164-176>179-195>200-210>214-226-227-235>238-262015-
AUSTIN-BRAZORIA-BRAZOS-BURLESON-CHAMBERS-COLORADO-FORT BEND-
GALVESTON-GRIMES-HARRIS-HOUSTON-JACKSON-LIBERTY-MADISON-MATAGORDA-
MONTGOMERY-POLK-SAN JACINTO-TRINITY-WALKER-WALLER-WASHINGTON-
WHARTON-
303 PM CDT WED MAY 25 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST TEXAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT

ISOLATED SEVERE THUNDERSTORMS ARE POSSIBLE...MAINLY LATE THIS
AFTERNOON THROUGH MIDNIGHT...NORTH OF OF THE HOUSTON METRO AREA.
A FRONT WILL PUSH INTO SOUTHEAST TEXAS TONIGHT AND A FEW
THUNDERSTORMS COULD DEVELOP ALONG IT. SHOULD THE THUNDERSTORMS
BREAK THROUGH THE CAPPING INVERSION...THE STORMS COULD BECOME
SEVERE GIVEN STRONG INSTABILITY. THE MAIN THREATS WILL BE LARGE
HAIL AND DAMAGING STRAIGHT LINE WINDS. ANY THUNDERSTORM ACTIVITY
SHOULD END BEFORE MIDNIGHT TONIGHT.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS EVENING AND TONIGHT.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
808 PM CDT WED MAY 25 2011

TXZ177-199-260200-
MONTGOMERY-WALKER-
808 PM CDT WED MAY 25 2011

...STRONG CELL IN NORTHWEST MONTGOMERY AND SOUTHWEST WALKER
COUNTIES....

AT 800 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 16 MILES SOUTHWEST OF HUNTSVILLE...MOVING EAST AT
20 MPH.

PEA SIZE HAIL...ARE POSSIBLE WITH THIS STORM. THIS STORM MAY
STRENGTHEN FURTHER AND WILL BE MONITORED FOR A POSSIBLE WARNING.

LOCATIONS IN THE PATH OF THIS STORM INCLUDE...CRABBS PRAIRIE...
RIVERSIDE AND HUNTSVILLE.

SEEK SHELTER IN A STURDY STRUCTURE OR NON-CONVERTIBLE AUTOMOBILE
UNTIL THIS STORM HAS PASSED.

LAT...LON 3060 9535 3052 9536 3049 9535 3047 9580
      3051 9582 3068 9583 3087 9539 3086 9535
TIME...MOT...LOC 0107Z 250DEG 18KT 3060 9575