Flash Flood Warning 46, NWS Houston/Galveston, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
309 PM CDT TUE AUG 28 2007

.DISCUSSION...
STORMS NOT COOPERATING WITH MY FORECAST SO FAR THIS EARLY AFTERNOON.
APPEARS THAT THE SEABREEZE WAS SLOW TO DEVELOP BENEATH THE CLOUD COVER
AND THE PC SKIES OVER THE HILL COUNTRY...HAS ALSO BEEN HAMPERED BY
SLIGHTLY HIGHER PRESSURES OVER THE CLL-ARM-VCT AREA. STORMS SHOULD
CONTINUE TO FIRE UP OVER THE WESTERN ZONES AND EXPAND INTO THE
CENTRAL AND EASTERN ZONES AS TEMPERATURES GET INTO THE LOWER 90S.
DO NOT SEE ANYTHING UPSTREAM THAT WILL KEEP STORMS GOING BEYOND
02Z SO WOULD ANTICIPATE THEM TO WEAKEN WITH THE COMING OF SUNSET.
SLIGHTLY RICHER MOISTURE SHOULD BE OVER THE AREA IN THE MORNING AS
THE UPPER LOW NEAR WACO STRETCHES AND LIFTS SLIGHTLY NORTHWARD
SETX SHOULD COME UNDER MORE DIVERGENT SOUTHWESTERLY FLOW ALOFT.
MODEL SOUNDINGS REMAIN UNSTABLE AND UNCAPPED BY MID AFTERNOON.
HAVE RAISED POPS IN SOME AREAS TO 60 PERCENT...UNDERCUTTING GFS
NUMBERS SLIGHTLY. (AGAIN HAVE THROWN OUT THE NAM SOLUTION DUE TO
IT ERRONEOUSLY DEVELOPING A LOW PRESSURE SYSTEM SOUTHEAST OF
PALACIOS AND DRAGGING IT NORTH FOR THE FOURTH RUN IN A ROW...NONE
OF WHICH HAVE OCCURRED SO FAR.) ON THURSDAY THE UPPER SHEAR AXIS
REMAINS FROM NEAR SHV-DRT AND A TUTT LOW IS MEANDERING ACROSS THE
CENTRAL AND WEST CENTRAL GULF...STALLING THERE THROUGH SATURDAY
MORNING AS THE RIDGE OVER THE FOUR CORNERS STRENGTHENS THEN SHIFTS
WEST AND WEAKENS SETTING THE STAGE FOR A POSSIBLE WEATHER PATTERN
CHANGE WITH ONLY A MODERATE RIDGE OVER THE SOUTHEAST U.S. AND FAST
ZONAL FLOW OREGON TO THE GREAT LAKES AND TROUGHING OVER CALIFORNIA
AND THE BAJA OF CALIFORNIA MID TO LATE NEXT WEEK.

SO FOR FRIDAY THROUGH MONDAY IT LOOKS LIKE DIURNALLY DRIVEN RAIN
CHANCES WITH A SLOW DECREASE IN COVERAGE AS SOME DRIER AIR GETS
INTO THE REGION. GFS/NAM/ECMWF/CANADIAN ALL PROG PRESSURES TO FALL
BETWEEN NEW ORLEANS AND APALACHICOLA WHICH SHOULD HELP TO BRING A
LIGHT NORTHERLY WIND INTO THE AREA FRIDAY AND SATURDAY THOUGH IT
WILL PROBABLY SUFFER FROM A GOOD SEABREEZE SETUP. THE GOOD NEWS IS
THAT WITH THE HIGH OFF TO THE NORTHEAST WE SHOULD END UP WITH A
LIGHT WIND REGIME AND SLIGHTLY COOLER BELOW NORMAL AFTERNOON HIGHS.

45
&&
ZCZC SATWRKAVN 000
TTAA00 KSAT 282008

.MARINE...
PRESSURE GRADIENT WILL REMAIN RELATIVELY FLAT THE NEXT SEVERAL DAYS.
WAVE HEIGHTS WILL REMAIN ON THE LOW SIDE. DEEP TROPICAL MOISTURE WILL
CONTINUE TO PREVAIL OVER THE REGION WITH MORE ACTIVITY LATE AT NIGHT
THROUGH MID MORNING HOURS. WE ADJUSTED WINDS TOWARD LATTER PART OF
WEEK REFLECTING LOWER PRESSURES EAST OF CWFA. JUST ABOUT ALL MODELS
AGREE IN DEVELOPING SURFACE TROUGHING/LOW PRESSURE EAST OF REGION RESULTING
IN WEAK NORTH TO NORTHWEST FLOW BY FRIDAY.
37

&&

.AVIATION...
MAIN CONVECTIVE ACTIVITY SHOULD BE MAINLY OVER THE WEST AND NORTHERN
PORTIONS OF CWFA THIS AFTERNOON BUT OTHER TAF SITES INCLUDING IAH AND
HOU STILL WILL HAVE CONVECTIVE SHOWERS NEARBY. WE EXPECT CONVECTION TO
DISSIPATE EARLY TO MID EVENING. PATCHY LIGHT FOG EXPECTED FOR CXO
...UTS...SGR AND LBX AFTER MIDNIGHT.
37

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      73  93  73  94  73 /  30  50  30  50  30
HOUSTON (IAH)              73  91  73  91  73 /  40  60  30  50  30
GALVESTON (GLS)            79  88  79  89  80 /  40  60  30  50  30

&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
541 AM CDT TUE AUG 28 2007

GMZ330-335-350-355-370-375-TXZ163-164-176>179-195>200-210>214-226-
227-235>238-291200-
AUSTIN-BRAZORIA-BRAZOS-BURLESON-CHAMBERS-COLORADO-FORT BEND-
GALVESTON-GALVESTON BAY-GRIMES-HARRIS-HOUSTON-JACKSON-LIBERTY-
MADISON-MATAGORDA-MATAGORDA BAY-MONTGOMERY-POLK-SAN JACINTO-
TRINITY-WALKER-WALLER-WASHINGTON-
WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM-
WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM-
WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM-
WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM-WHARTON-
541 AM CDT TUE AUG 28 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST TEXAS.

.DAY ONE...TODAY AND TONIGHT

SCATTERED SHOWERS AND THUNDERSTORMS WILL BECOME MORE NUMEROUS THIS
AFTERNOON. BECAUSE OF WEAK STEERING CURRENTS ALOFT AND AN
ABUNDANCE OF GULF MOISTURE AVAILABLE...LOCALLY HEAVY RAINFALL WILL
BE POSSIBLE THAT MAY LEAD TO MINOR FLOODING OF LOW-LYING AREAS AND
ROADWAYS. IN ADDITION...ISOLATED STRONG STORMS MAY PRODUCE SMALL
HAIL AND STRONG GUSTY WINDS. AVERAGE RAINFALL AMOUNTS OF ONE
QUARTER TO ONE HALF INCH CAN BE EXPECTED ACROSS SOUTHEAST TEXAS.
HOWEVER...ISOLATED TOTALS OF ONE TO THREE INCHES ARE POSSIBLE IN
THE SLOWER MOVING STRONGER STORMS.

.DAYS TWO THROUGH FOUR...WEDNESDAY THROUGH FRIDAY

FAVORABLE CONDITIONS FOR LOCALLY HEAVY RAINFALL WILL CONTINUE
ACROSS SOUTHEAST TEXAS. SCATTERED TO NUMEROUS THUNDERSTORMS ARE
EXPECTED TO DEVELOP MAINLY DURING THE LATE MORNING TO EARLY
EVENING EACH DAY. THE STRONGER STORMS WILL POSSIBLY GENERATE
MINOR FLOODING OF LOW-LYING AREAS AND ROADWAYS.

.DAYS FIVE THROUGH SEVEN...SATURDAY THROUGH MONDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.