Severe Thunderstorm Warning 60, NWS Brownsville, TX

DEEP SOUTH TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
300 AM CDT MON JUL 2 2001

DISCUSSION...THE MAIN ANALYZED FEATURES AT 02/06Z INCLUDE A 586 DM
UPPER LOW TO THE WEST OF THE BAJA PENINSULA...A 596 DM UPPER HIGH
CENTERED NEAR THE FOUR CORNERS...WITH ASSOCIATED RIDGE AXIS
EXTENDING NORTH FROM THE HIGH CENTER INTO CANADA...AND ASSOCIATED
1025 MB SURFACE HIGH OVER LAKE MICHIGAN...A 540 DM UPPER LOW JUST
NORTHWEST OF MAINE...WITH ASSOCIATED 991 MB SURFACE LOW JUST NORTH
OF MAINE...AND ASSOCIATED SURFACE COLD FRONT EXTENDING SOUTH ALONG
THE ATLANTIC SEABOARD...THEN EXTENDING WEST ALONG THE OHIO RIVER
VALLEY.  SURFACE HIGH PRESSURE EXTENDS EAST FROM THE WEST ATLANTIC
INTO THE GULF OF MEXICO...WITH FLAT MID LEVEL HEIGHTS ACROSS THE
REGION.  UPPER DIVERGENCE OVER THE EAST GULF IS CONSIDERED FAVORABLE
FOR POTENTIAL SURFACE CYCLOGENESIS AND IS BEING MONITORED.

SATELLITE IMAGERY REVEALS A COUPLE OF UPPER CIRCULATIONS OF CONCERN
FOR DEEP SOUTH TEXAS...ONE OVER NORTHEAST TEXAS AND ANOTHER IN THE
WEST GULF.  THE WEST GULF UPPER CIRCULATION APPEARS TO BE THE MAIN
CENTER ABOUT WHICH SMALLER CIRCULATIONS ARE REVOLVING.  THIS
CIRCULATION WILL SLOWLY DIE OUT OVER THE NEXT FEW DAYS...BUT
SCATTERED SHOWERS AND THUNDERSTORMS WILL REMAIN IN THE AREA TODAY
AND TOMORROW... TAPERING OFF AROUND THE FOURTH OF JULY.  INCREASING
PRECIPITABLE WATER (1.80 INCHES) AND A WEAK MEAN FLOW WILL RESULT IN
SHOWERS WITH HEAVIER LOCAL DOWNPOURS...WHILE HIGH SURFACE DEWPOINTS
(IN THE MID 70S NEAR THE COAST)...AND A VEERING PROFILE WITH WEAK TO
MODERATE SHEAR (30 KNOTS)...COULD SUPPORT WEAK ROTATION AND SOME
ISOLATED SEVERE THUNDERSTORMS...AS WAS THE CASE WITH A WEAK
SUPERCELL THAT PERSISTED OVER JIM HOGG COUNTY YESTERDAY...DROPPING 6
INCHES OF RAIN IN ONE HOUR OVER THE SAME SPOT.  DEEP SOUTH TEXAS IS
IN A GENERAL THUNDERSTORM OUTLOOK AREA FOR TODAY.

VERY LITTLE RAIN IS BEING REPORTED AT OBSERVING SITES THUS
FAR...DESPITE SOME HEAVIER RADAR DERIVED STORM TOTALS.  FOR
EXAMPLE...HEAVY DOWNPOURS WERE NOTED ALONG THE RIO GRANDE RIVER NEAR
FALCON DAM YESTERDAY MORNING...BUT THE COOP SITE ONLY REPORTED A
PALTRY 0.04 INCHES.  THE RIVER STAGE BELOW FALCON DAM HAS RISEN
ABOUT ONE FOOT IN THE LAST COUPLE OF DAYS...BUT LITTLE CHANGE HAS
BEEN NOTED IN THE RESERVOIR ITSELF.

THE CURRENT FORECAST PACKAGE HAS THE PRECIP TREND WELL IN HAND...BUT
WILL MAKE SOME SMALL ADJUSTMENTS...INCLUDING BUMPING UP POPS
SLIGHTLY FOR TODAY BASED ON INCREASING PWAT TREND AND PROXIMITY OF
UPPER VORTICITY.  IN ADDITION...MONTE CARLO EFFECT SAYS THAT A
SHOWER WILL EVENTUALLY DOUSE BRO.  SUNSHINE HAS BEEN 80 TO 90
PERCENT...SO EXCEPT FOR PERIODS OF SHOWERS AND THUNDERSTORMS...
PARTLY CLOUDY WILL BE WORDED.  RADAR ANALYSIS SHOWS SHOWER ACTIVITY
TENDS TO START CLOSER TO THE COAST DURING LATE MORNING...AS EARLY
MORNING STABILITY IS OVERCOME...WITH CONVECTION THEN MOVING
PROGRESSIVELY WEST DURING THE AFTERNOON AND EARLY EVENING.

THE UPPER PATTERN CHANGES ONLY A LITTLE IN THE MEDIUM RANGE...WITH
THE UPPER RIDGE AXIS REMAINING OVER THE WEST...AND THE BASE HIGH
CENTER SLIDING TOWARD NORTH TEXAS/OKLAHOMA BY FRIDAY.  THE MEAN
TROUGH OVER THE EAST ABSORBS SHORT WAVE TROUGHS SLIDING ACROSS SOUTH
CANADA ALONG THE POLAR JET TRACK.  WITH PWAT REMAINING HIGHER
THROUGH THURSDAY...WILL KEEP SOME SHOWERS IN THE FORECAST INTO THE
EXTENDED...BUT LONG RANGE GUIDANCE THEN INDICATES SUNNIER SKIES
GOING INTO THE WEEKEND.  SOME ISOLATED SEA BREEZE SHOWERS ARE LIKELY
TO PERSIST EVEN THEN HOWEVER...AS DEWPOINTS STAY UP...AND HEATING
WILL REMAIN STRONG.

MARINE...A GENTLE TO MODERATE BREEZE AND LOW SEAS WILL PREVAIL
THROUGH THE FORECAST PERIOD EXCEPT FOR HIGHER...GUSTY WINDS AND
HIGHER SEAS IN AND NEAR SCATTERED SHOWERS AND THUNDERSTORMS.  NO
ADVISORIES ARE EXPECTED.

PRELIMINARY NUMBERS...
BRO BB 091/076 091/075 092 53423
HRL BB 093/076 093/074 094 53423
MFE BB 095/075 095/075 096 54433
RGC BB 099/075 099/074 100 54433
SPI BB 087/078 087/078 088 42312

AVIATION-MARINE-MESO (LEAD)...58.JP/SYNOPTIC-PUBLIC...54.BHM

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

.BRO...NONE.

TXZ252-253-255-021045-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BROWNSVILLE TX
341 AM CDT MON JUL 2 2001

...SHOWERS AND THUNDERSTORMS TRAIN ACROSS SOUTHWESTERN HIDALGO
COUNTY...

AN UPPER LEVEL DISTURBANCE OVER THE CENTRAL GULF OF MEXICO IS
EJECTING MOISTURE AND LIFT TO DEEP SOUTH TEXAS. SHOWERS AND
THUNDERSTORMS DEVELOPED SOUTH OF HIDALGO COUNTY AROUND
MIDNIGHT...AND HAVE CONTINUED TO DEVELOP NORTHWEST INTO SOUTHWESTERN
HIDALGO AND SOUTHEASTERN STARR COUNTIES. THESE SHOWERS AND
THUNDERSTORMS HAVE BEEN MOVING OVER THE SAME AREAS OF HIDALGO AND
STARR COUNTIES DURING THE PAST THREE HOURS...LEAVING 1/2 TO 1 INCH
OF RAINFALL.

SHOWER AND THUNDERSTORM ACTIVITY WILL CONTINUE TODAY...AS SYNOPTIC
CONDITIONS MAINTAIN THEMSELVES...AND DAYTIME HEATING ADDS TO THE
LIFTING PROCESS.

DRIVE WITH CARE DURING YOUR MONDAY MORNING COMMUTE...ESPECIALLY IN
MISSION...MCALLEN AND ROADS IN SOUTHWESTERN HIDALGO COUNTY.

STAY TUNED TO THE NATIONAL WEATHER SERVICE FOR THE LATEST WEATHER
INFORMATION. PHILO

TXZ248>257-021800-

DEEP SOUTH TEXAS THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE BROWNSVILLE TX
532 AM CDT MON JUL 2 2001

...SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY...

AN UPPER LEVEL DISTURBANCE WILL COMBINE WITH TROPICAL MOISTURE TO
PRODUCE SHOWERS AND THUNDERSTORMS TODAY. SINCE WINDS ARE RELATIVELY
LIGHT...THE SHOWERS AND THUNDERSTORMS WILL MOVE SLOWLY.

AS A RESULT...LOCALLY HEAVY RAINFALL IS EXPECTED...WITH RAINFALL AMOUNTS
IN EXCESS OF TWO INCHES POSSIBLE.  HOWEVER...AVERAGE RAINFALL AMOUNTS
SHOULD BE AROUND ONE HALF OF AN INCH TO AN INCH.

ALONG WITH THE LOCALLY HEAVY RAINFALL...DANGEROUS CLOUD TO GROUND
LIGHTNING...STRONG GUSTY WINDS...AND POSSIBLY SOME SMALL HAIL IS
EXPECTED WITH THE STRONGER THUNDERSTORMS.  NO SEVERE WEATHER IS
EXPECTED...ALTHOUGH AN ISOLATED THUNDERSTORM COULD APPROACH SEVERE
LIMITS...PRODUCING HAIL NEAR THE SIZE OF A DIME...AND WIND GUSTS NEAR
60 MPH.

SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED AGAIN TOMORROW...AND ON
WEDNESDAY...THE FOURTH OF JULY...HOWEVER...ANY SHOWERS AND THUNDERSTORMS
ON THE FOURTH ARE EXPECTED TO BE LESS INTENSE...AS THE UPPER
DISTURBANCE MOVES AWAY.

MILLER