Flash Flood Warning 34, NWS Houston/Galveston, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
230 PM CDT WED JUN 23 2004

.DISCUSSION..
KHGX RADAR BEGINNING TO GET MORE ACTIVE AS A CLUSTER
OF SHOWERS AND THUNDERSTORMS HAS DEVELOPED OVER THE SW
ZONES AND IS SLOWLY ADVANCING N/NE. THERE IS SOME ACTIVITY
ALONG THE QUASI-STATIONARY FRONT POSITIONED JUST NW OF THE
AREA AS WELL. A COUNTER CLOCKWISE SPIN IS VERY APPARENT ON VIS
SAT LOOP...CENTERED JUST SW OF THE AREA AND SHOWS THE LOCATION
OF THE MID-LEVEL LOW WHICH IS AIDING THE ABOVE MENTIONED
CONVECTION. AS HEATING CONTINUES AND THE ATMOSPHERE CONTINUES
TO RECOVER FROM THE EARLY MORNING RAIN...WE SHOULD BE IN FOR
INCREASING SHWR/TSTM COVERAGE THE REMAINDER OF THE AFT AND INTO
THE EVE HOURS.

THE MAIN FORECAST ISSUE CONTINUES TO BE THE HEAVY RAIN/FLOOD
THREAT ACROSS THE AREA. 12Z MODELS ARE IN GOOD AGREEMENT
CONCERNING HIGH POPS AND HIGHEST QPF OVER SE TX THIS AFTERNOON
AND TONIGHT. AM CONCERNED THAT THE FLOOD THREAT WILL EXTEND
INTO THE NW ZONES BASED ON THE NORTHWARD EXTENT OF THE VERY
HIGH PW AIR AND MODEL FORECAST OF WEAK LOW PRESSURE FORMING
OVER THE CENTRAL ZONES TONIGHT. ALL OF THE CWA IS SOUTH OF
THE WEAK FRONT AND THEREFORE SUBJECT TO THE THREAT OF HEAVY
RAINFALL TONIGHT. STILL THINK THAT THE MOST LIKELY AREA TO
EXPERIENCE HEAVY RAINFALL AND THE HIGHEST AMOUNTS IS ALONG AND
SOUTHEAST OF A COLUMBUS TO CONROE TO LIVINGSTON LINE. SET-UP
IS NOT EXACTLY THE SAME AS YESTERDAY EVE AS THERE IS NO
WELL-DEFINED OUTFLOW BOUNDARY ALONG THE COAST TO PROVIDE
CONVERGENCE ALONG A COASTAL TROF. AVG AMOUNTS OF 1 TO 3
INCHES FOR THIS AFT AND THROUGH THE OVERNIGHT HOURS IS WHAT
IS EXPECTED...WITH ISOLATED AMOUNTS OF 5 TO 8 INCHES POSSIBLE.

AM UNSURE IF THE FLOOD THREAT WILL EXTEND MUCH INTO THU MORN.
WILL LET SUBSEQUENT SHIFTS MAKE THE DECISION ON WHETHER TO
EXTEND THE WATCH THROUGH THURSDAY BASED ON CONVECTIVE TRENDS
TONIGHT. WILL MAINTAIN GOOD CHCS FOR RAIN ON FRI AND SAT AS
THE AREA WILL BE PLENTY MOIST AND UNSTABLE WITH ANOTHER
SIGNIFICANT DISTURBANCE POSITIONED WEST OF THE AREA.
&&

.HGX WATCHES/WARNINGS/ADVISORIES...
FFA ALL OF SOUTHEAST TX UNTIL 11Z THURSDAY.
SCEC 20 TO 60 NM HIGH ISLAND TO THE MATAGORDA SHIP CHANNEL.
&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 71 88 73 88 72/ 70 50 30 50
HOUSTON(IAH)          72 85 73 87 73/ 90 60 30 50
GALVESTON (GLS)       74 84 76 86 77/ 90 70 40 50
&&

33/41

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
345 PM CDT WED JUN 23 2004

TXZ163-164-176>179-195>200-210>214-226-227-235>238-241200-
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-
345 PM CDT WED JUN 23 2004

...FLOOD WATCH IS IN EFFECT FOR ALL OF SOUTHEAST TEXAS
THROUGH TONIGHT...
...ISOLATED FUNNEL CLOUDS OR TORNADOES POSSIBLE THIS
AFTERNOON AND TONIGHT...

.DAY ONE...TONIGHT.
AN UPPER LEVEL DISTURBANCE WILL COMBINE WITH A MOIST AND
UNSTABLE AIRMASS TO PRODUCE NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS
SOUTHEAST TEXAS TONIGHT. LOCALLY HEAVY RAINFALL IS PROBABLE
...WHICH COULD LEAD TO FLOODING PROBLEMS ACROSS THE AREA.

OVER THE LAST 24 HOURS...RAINFALL AMOUNTS HAVE AVERAGED 1 TO 3 INCHES
GENERALLY ALONG AND SOUTH OF INTERSTATE 10...WITH TOTALS OF 3 TO 8
INCHES OBSERVED OVER PORTIONS OF JACKSON...MATAGORDA...BRAZORIA...AND
GALVESTON COUNTIES.

THROUGH TONIGHT...ADDITIONAL RAINFALL AMOUNTS WILL RANGE FROM 1 TO 3
INCHES ACROSS SOUTHEAST TEXAS...WITH ISOLATED TOTALS OF 5 TO 8 INCHES
POSSIBLE. WITH THE GROUND ALREADY SATURATED FROM PREVIOUS RAINFALL...
THESE ADDITIONAL HEAVY RAINS COULD CAUSE FLOODING PROBLEMS.

CONDITIONS ARE FAVORABLE FOR THE FORMATION OF FUNNEL CLOUDS AND
BRIEF TORNADOES TONIGHT. WINDS IN THE LOWER ATMOSPHERE ARE
TURNING WITH HEIGHT SUFFICIENTLY TO PRODUCE THIS THREAT. THIS TURNING
IS DUE TO THE MID LEVEL LOW PRESSURE AREA THAT IS SLOWLY ADVANCING
NORTHEAST ACROSS SOUTHEAST TEXAS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

THURSDAY...AN UPPER LEVEL DISTURBANCE WILL PRODUCE NUMEROUS SHOWERS
AND THUNDERSTORMS ACROSS SOUTHEAST TEXAS...WITH THE CONTINUED THREAT
OF LOCALLY HEAVY RAINFALL. RAIN IS EXPECTED TO TAPER OFF LATE
THURSDAY.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS POSSIBLE TONIGHT.