Flash Flood Warning 4, NWS Houston/Galveston, TX

SOUTHEAST TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
235 PM CDT SAT JUL 13 2002

RATHER WIDESPREAD CONVECTIVE COVERAGE ACROSS EASTERN HALF OF CWA
THIS AFTN. SEABREEZE BEGINNING TO SNEAK INLAND SO WILL LIKELY SEE
ADDITIONAL DEVELOPMENT OVER THE COASTAL ZONES NEXT COUPLE OF HOURS.
ISOLATED DOWNBURSTS REMAIN A POSSIBILITY THIS EVENING WITH SLIGHTLY
DRIER AIR IN LOWEST 3000 FEET.

12Z MODELS IN GOOD AGREEMENT ON EVOLUTION OF LARGE SCALE PATTERN.
500 MB LOW OVER NORTHEAST OKLAHOMA WILL SINK SOUTHWARD TO THE
ARKLATEX AREA SUNDAY THEN STALL AND SLOWLY FILL THROUGH THE EARLY
PART OF THE WEEK. THIS SYSTEM WILL KEEP CWA IN DEEP TROPICAL
MOISTURE (PWS 2.0-2.2 INCHES) AND SIGNIFICANT UPPER LEVEL DIFLUENCE
THROUGH MONDAY. WILL CONTINUE TO SEE SYNOPTIC FORCING FROM WEAK
SHORTWAVES ROTATING AROUND UPPER LOW...WITH MESOSCALE BOUNDARIES AND
THE SEABREEZE ACTING AS SURFACE FOCUSES FOR CONVECTION. BOTH ETA/AVN
DEPICT FIRST SHORTWAVE PUSHING ACROSS NORTH TX THIS EVENING
INITIATING ANOTHER ROUND OF TSRA THAT WILL PUSH INTO NRN ZONES
OVERNIGHT. MODELS SHOW CWA MOVING INTO RRQ OF JET STREAK LATE SUNDAY
AND SUNDAY NIGHT WITH UVV INCREASING ACROSS CWA. FINALLY...12Z AVN
PICKS UP ON A NEW SURGE OF TROPICAL MOISTURE (PWS AROUND 2.2 INCHES)
THAT WILL SPREAD INTO SE TX MONDAY. ALL OF THIS POINTS TO HIGH POPS
THROUGH MONDAY...WITH DYNAMICS ALLOWING CONVECTION TO LINGER THROUGH
THE OVERNIGHT HOURS DESPITE LOSS OF DAYTIME HEATING. WILL HAVE
HIGHEST POPS IN NE ZONES THROUGH PERIOD.

500 MB RIDGE WILL STRENGTHEN OVER THE SOUTHEAST STATES AND BEGIN TO
RIDGE WESTWARD OVER TEXAS STARTING TUESDAY. 12Z AVN SHOWS
SIGNIFICANT DRYING SPREADING ACROSS CWA FROM THE SOUTH BY TUE
NIGHT...WITH PWS DROPPING TO 1.4 TO 1.5 INCH RANGE. WILL LOWER POPS
TO 20 PERCENT FROM WEDNESDAY ONWARD...WITH MAX TEMPS CLIMBING INTO
THE MID TO UPPER 90S. NORMAL HIGHS FOR JULY 15TH-30TH ARE 96 AT CLL
AND 94 AT IAH...SO NO SURPRISES FOR THIS TIME OF YEAR.

35/42

.HGX...NONE.

PRELIMS...
CLL TT 074/092 074/091 074 454 NE ZONES 565
IAH TT 075/092 076/090 076 454
GLS TT 080/089 080/087 080 453 SW ZONES 343

TXZ163-164-176>179-195>200-211>214-227-237-238-140900-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
340 PM CDT SAT JUL 13 2002

...THREAT FOR LOCALLY HEAVY RAINFALL ACROSS MOST OF SOUTHEAST
TEXAS THROUGH SUNDAY...

DEEP TROPICAL MOISTURE FROM THE GULF WILL COMBINE WITH UPPER LEVEL
DISTURBANCES TO PRODUCE SCATTERED SHOWERS AND THUNDERSTORMS ACROSS
SOUTHEAST TEXAS THROUGH SUNDAY. HEAVY DOWNPOURS ASSOCIATED WITH THESE
STORMS COULD PRODUCE RAINFALL RATES OF 2 TO 3 INCHES PER HOUR IN A
FEW SPOTS. THE LOCALIZED HEAVY RAINS COULD LEAD TO HIGH STANDING WATER
ON ROADS AND UNDERPASSES...AND IN AREAS OF POOR DRAINAGE. WATER
LEVELS WILL RISE IN AREAS OF HEAVY RAIN...BUT SIGNIFICANT OVERFLOWS OF
STREAMS AND BAYOUS IS NOT ANTICIPATED.

USE CAUTION WHEN DRIVING IN HEAVY RAIN. DEEP PUDDLES ON ROADS CAN
CAUSE YOUR VEHICLE TO HYDRO-PLANE IF YOU ARE TRAVELING AT HIGH
SPEEDS. HIGH STANDING WATER ON FEEDER ROADS MAY BE TOO DEEP FOR
YOU TO CROSS WITHOUT STALLING. AVOID DRIVING THROUGH HIGH WATER.

STAY TUNED TO NOAA WEATHER RADIO OR OTHER WEATHER NEWS SOURCES FOR
FURTHER UPDATES ON THIS THREAT OF HEAVY RAIN. YOU CAN ALSO
VISIT US ON THE INTERNET AT WWW.SRH.NOAA.GOV/HGX.