Flash Flood Warning 6, NWS Brownsville, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
729 AM CDT TUE MAY 18 2010

.UPDATE...UPDATED THE AVIATION DISCUSSION

&&

.AVIATION...THUNDERSTORMS ARE INCREASING IN COVERAGE OVER DEEP
SOUTH TEXAS. MAIN LINE OVER THE NORTHWEST PORTIONS OF THE REGION
TO SWEEP ACROSS THE MIDDLE AND LOWER VALLEYS BETWEEN 8 AND 10 AM.
ADDITIONAL SHOWERS AND THUNDERSTORMS ARE DEVELOPING IN ADVANCE OF
THE MAIN LINE AND COULD AFFECT KBRO...KPIL AND KHRL. CIGS AND VSBY
TO LOWER MVFR TO IFR IN AND NEAR THE THUNDERSTORMS WITH WIND GUSTS
IN EXCESS OF 40 KNOTS. THE STORM COMPLEX SHOULD EXIT INTO THE GULF
BY NOON IF NOT EARLIER WITH ONLY ISOLATED THUNDERSTORMS TO
POSSIBLY REDEVELOP THIS AFTENROON.

&&

.PREV DISCUSSION... /ISSUED 651 AM CDT TUE MAY 18 2010/

UPDATE...SEVERE THUNDERSTORMS WATCH 184 ISSUED BY SPC AND WFO BRO
UNTIL NOON TODAY. THUNDERSTORM COMPLEX CURRENTLY MOVING THROUGH
ZAPATA AND JIM HOGG COUNTIES. THE LINE OF STRONG TO OCCASIONALLY
SEVERE STORMS IS MOVING EAST TO SOUTHEAST AT AROUND 25 MPH. THE
STORMS TO MOVE INTO BROOKS AND STARR BETWEEN 7 AND 8 AM SPREADING
INTO HIDALGO AND THE LOWER VALLEY BETWEEN 8 AND 10 AM. INDIVIDUAL
SHOWERS AND STORMS ARE DEVELOPING IN ADVANCE OF THE MAIN SYSTEM AS
UPPER DIVERGENT FLOW AND INSTABILITY INCREASES AS A MID LEVEL
DISTURBANCE APPROACHES FROM THE WEST.

PREV DISCUSSION... /ISSUED 435 AM CDT TUE MAY 18 2010/

UPDATE...DID A QUICK UPDATE TO THE FORECAST WORDING TO REFLECT
THE POTENTIAL FOR STRONG TO SVR CONV ACROSS THE NORTHERN FOUR
COUNTIES OF ZAPATA...JIM HOGG...BROOKS AND KENEDY THIS MORNING.
NO OTHER CHANGES NEEDED AT THIS TIME.

PREV DISCUSSION... /ISSUED 352 AM CDT TUE MAY 18 2010/

SHORT TERM /TODAY THROUGH 7 PM WEDNESDAY/...LARGE THUNDERSTORM
COMPLEX RAGING ALONG THE RIO GRANDE RIVER RIGHT NOW...NORTH OF
LAREDO AND SOUTH OF DEL RIO. MOVEMENT OF THIS CONVECTION IS MAINLY
TO THE EAST...WITH SOME SOUTHEAST COMPONENT. WILL INDICATE SOME
SHOWERS AND THUNDERSTORMS IN THE UPCOMING ZONE FORECAST IN RESPONSE
TO THIS ACTIVITY. DRIER CONDITIONS ANTICIPATED FOR WEDNESDAY...WITH
SURFACE WINDS POSSIBLY NECESSITATING A SMALL CRAFT ADVISORY FOR
MARINERS ON THE LAGUNA MADRE.

LONG TERM...THE 500 MB FLOW PATTERN IN THE LONGER RANGE PERIOD
WILL BE DOMINATED BY A SHARPLY DIGGING 500 MB TROUGH PUSHING INTO
THE WEST COAST OF THE U.S. AT THE SAME TIME A BROAD CLOSED LOW
WILL FORM OVER THE EAST COAST. THE COMBINATION OF THESE TWO
FEATURES WILL RESULT IN A BUILDING RIDGE OVER MUCH OF THE WESTERN
GULF OF MEX AND THE TX COASTLINE. THIS WILL MAINTAIN FAIRLY STATUS
QUO TEMPS AND POPS ACROSS THE REGION WITH TEMPS ABOVE CLIMO AND
POPS BELOW CLIMO. RUN TO RUN CONSISTENCY WITH THE GFS MEX GUIDANCE
SHOWS GOOD STABILITY FOR BOTH TEMPS AND POPS WHILE MODEL TO MODEL
CONSISTENCY WITH THE GFS AND THE ECMWF REMAINS PRETTY GOOD ALSO.
WILL REMAIN NEAR OR A LITTLE ABOVE GUIDANCE FOR TEMPS AND NEAR
ZERO FOR POPS IN THE EXTENDED RANGE PERIOD.

MARINE...TODAY THROUGH 7 PM WEDNESDAY...BUOY 42020 REPORTED EAST-
SOUTHEAST WINDS AROUND 12 KNOTS GUSTING TO AROUND 14 KNOTS WITH
SEAS SLIGHTLY UNDER 2.5 FEET WITH A PERIOD OF 7 SECONDS AT 02
CDT/07 UTC. LIGHT TO MODERATE WINDS AND LOW TO MODERATE SEAS WILL
PREVAIL ALONG THE LOWER TEXAS COAST TODAY AND TONIGHT AS HIGH
PRESSURE OVER THE GULF OF MEXICO BEGINS TO INTERACT WITH A LOW
PRESSURE SYSTEM FORMING OVER NORTHEAST MEXICO. AS THESE TWO
SYSTEMS BEGIN TO INTERACT MORE INTENSELY ON WEDNESDAY...WINDS AND
SEAS WILL INCREASE...AND A SMALL CRAFT ADVISORY MAY BE NEEDED FOR
THE LAGUNA MADRE.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  91  76  90  78 /  50   0   0   0
BROWNSVILLE          92  75  91  77 /  50   0   0   0
HARLINGEN            94  75  95  76 /  50   0   0   0
MCALLEN              96  75  96  76 /  50   0   0   0
RIO GRANDE CITY     101  75 100  75 /  50   0   0   0
SOUTH PADRE ISLAND   87  78  87  76 /  50   0   0   0

&&

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

THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:
HTTP://WWW.WEATHER.GOV/BROWNSVILLE

59/51

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
630 AM CDT TUE MAY 18 2010

GMZ130-132-135-150-155-170-175-TXZ248>257-191100-
LAGUNA MADRE FROM THE PORT OF BROWNSVILLE TO THE ARROYO COLORADO-
LAGUNA MADRE FROM THE ARROYO COLORADO TO 5 NM NORTH OF PORT
MANSFIELD TX-
LAGUNA MADRE FROM 5 NM NORTH OF PORT MANSFIELD TO BAFFIN BAY TX-
COASTAL WATERS FROM PORT MANSFIELD TO THE RIO GRANDE OUT 20 NM-
COASTAL WATERS FROM BAFFIN BAY TO PORT MANSFIELD OUT 20 NM-
WATERS FROM PORT MANSFIELD TO THE RIO GRANDE EXTENDING FROM 20 TO
60 NM-
WATERS FROM BAFFIN BAY TO PORT MANSFIELD EXTENDING FROM 20 TO
60 NM-ZAPATA-JIM HOGG-BROOKS-KENEDY-STARR-HIDALGO-INLAND WILLACY-
INLAND CAMERON-COASTAL WILLACY-COASTAL CAMERON-
630 AM CDT TUE MAY 18 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR DEEP SOUTH TEXAS...THE GULF
OF MEXICO AND THE LAGUNA MADRE.

.DAY ONE...TODAY AND TONIGHT.

STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE THIS MORNING OVER ALL OF
DEEP SOUTH TEXAS PRODUCING LARGE HAIL AND DAMAGING WINDS. A SEVERE
THUNDERSTORM WATCH IS IN EFFECT FOR ALL OF DEEP SOUTH TEXAS AND THE
ADJACENT COASTAL WATERS UNTIL NOON TODAY.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

A SMALL CRAFT ADVISORY MAY BE NEEDED ALONG THE LOWER TEXAS COAST...
ESPECIALLY THE LAGUNA MADRE...DUE TO INCREASING WINDS. A MODERATE
RISK OF RIP CURRENTS AT THE BEACHES OF SOUTH PADRE ISLAND AND BOCA
CHICA WILL LIKELY ACCOMPANY THE STRONGER WINDS.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTER ACTIVATION WILL LIKELY BE NEEDED THIS MORNING.

SPEECE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BROWNSVILLE TX
413 AM CDT TUE MAY 18 2010

TXZ248>251-181115-
ZAPATA-JIM HOGG-BROOKS-KENEDY-
INCLUDING THE CITIES OF...ZAPATA...HEBBRONVILLE...FALFURRIAS...
SARITA
413 AM CDT TUE MAY 18 2010

...SEVERE THUNDERSTORMS LOCATED JUST NORTH OF THE REGION...

NATIONAL WEATHER SERVICE DOPPLER RADAR IN BROWNSVILLE IS TRACKING
A LARGE AREA OF SEVERE THUNDERSTORMS...LOCATED OVER WEBB AND DUVAL
COUNTY. THE MOST INTENSE PORTION OF THE SEVERE THUNDERSTORMS IS
LOCATED ABOUT 34 MILES NORTHWEST OF HEBBRONVILLE...WITH THE WHOLE
THUNDERSTORM COMPLEX MOVING GENERALLY TO THE EAST AND SOUTHEAST AT
AROUND 20 MPH.

LARGE HAIL AND DAMAGING WINDS MAY AFFECT PORTIONS OF ZAPATA...JIM
HOGG...BROOKS...AND KENEDY COUNTY WITHIN THE NEXT COUPLE OF HOURS.
RESIDENTS IN THESE COUNTIES SHOULD MONITOR LOCAL MEDIA SOURCES FOR
THE LATEST INFORMATION REGARDING THIS DEVELOPING WEATHER SITUATION.

TOMASELLI

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BROWNSVILLE TX
744 AM CDT TUE MAY 18 2010

TXZ249>253-181445-
JIM HOGG-BROOKS-KENEDY-STARR-HIDALGO-
INCLUDING THE CITIES OF...HEBBRONVILLE...FALFURRIAS...SARITA...
RIO GRANDE CITY...ROMA...MCALLEN...EDINBURG...PHARR...MISSION...
WESLACO
744 AM CDT TUE MAY 18 2010

...SEVERE THUNDERSTORMS POSSIBLE ACROSS DEEP SOUTH TEXAS THIS MORNING...

AT 740 AM...NATIONAL WEATHER SERVICE DOPPLER RADAR IN BROWNSVILLE
INDICATED A LINE OF STRONG THUNDERSTORMS FROM NEAR FALFURRIAS IN
BROOKS COUNTY EXTENDING SOUTHWEST TO NEAR ROMA IN SOUTHWESTERN
STARR COUNTY. THESE THUNDERSTORMS WERE ALL MOVING GENERALLY EAST
SOUTHEAST AT 15 TO 20 MPH AND WILL PRODUCE WIND GUSTS FROM 35 TO
45 MPH...PERIODS OF LOCALLY HEAVY RAIN...PEA TO MARBLE SIZE HAIL
AND FREQUENT LIGHTNING THROUGH 10 AM THIS MORNING.

THE STRONGEST OF THESE THUNDERSTORMS WILL AFFECT STARR...
SOUTHEASTERN JIM HOGG...BROOKS...HIDALGO...KENEDY...WILLACY AND
CAMERON COUNTIES THROUGH 10 AM.

A SEVERE THUNDERSTORM WATCH IS IN EFFECT FOR ALL OF DEEP SOUTH
TEXAS UNTIL NOON TODAY.

ALSO...AHEAD OF THIS LINE OF STRONG THUNDERSTORMS...OTHER
ISOLATED STRONG THUNDERSTORMS HAVE FORMED OVER THE SOUTHERN LAGUNA
MADRE AND ABOUT 50 NAUTICAL MILES OFFSHORE OF KENEDY COUNTY.

RESIDENTS OF DEEP SOUTH TEXAS SHOULD STAY TUNED TO NOAA WEATHER
RADIO...LOCAL TELEVISION AND RADIO STATIONS AND THE NATIONAL
WEATHER SERVICE OFFICE BROWNSVILLE WEB SITE AT WWW.WEATHER.GOV/RGV
FOR ADDITIONAL STATEMENTS CONCERNING THIS DEVELOPING WEATHER
SITUATION.

SPEECE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BROWNSVILLE TX
902 AM CDT TUE MAY 18 2010

TXZ253>255-181500-
INLAND WILLACY-INLAND CAMERON-HIDALGO-
902 AM CDT TUE MAY 18 2010

...SMALL HAIL WILL AFFECT SOUTHEAST HIDALGO COUNTY...

A LINE OF THUNDERSTORMS...MOVING SOUTHEAST AT 35 MPH...WILL AFFECT
WESLACO...DONNA...EDCOUCH AND MERCEDES...UNTIL 1000 AM CDT. GUSTY
WINDS UP TO 40 MPH WILL OCCUR. FREQUENT CLOUD TO GROUND LIGHTNING IS
EXPECTED. IF CAUGHT OUTSIDE...CROUCH DOWN IN A LOW SPOT...AWAY FROM
TALL OBJECTS. NICKEL SIZE HAIL IS EXPECTED. RAINFALL RATES OF 1 TO 2
INCHES PER HOUR WILL OCCUR. MOTORISTS CAN EXPECT PONDING OF WATER ON
ROADS...AND MINOR FLOODING OF POOR DRAINAGE AREAS.

61/MC