Flash Flood Warning 8, NWS Houston/Galveston, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
942 PM CST SAT JAN 13 2007

.UPDATE...
THE SLOW MOVING COLD FRONT WAS CONTINUING TO TREK EASTWARD ACROSS
SE TX THIS EVENING. NUMEROUS SHOWERS AND THUNDERSTORMS WERE
OCCURRING MAINLY BEHIND THE FRONT. WITH PW/S AROUND 1.7 INCHES...
AM EXPECTING WIDESPREAD RAINFALL AMOUNTS OF 2 TO 3 INCHES WITH
ISOLATED AMOUNTS UP TO 5 INCHES WHERE THE CORE OF THE HEAVY
RAINFALL OCCURS. THE FRONT HAD JUST MOVED THROUGH DWH AND CXO AND
WAS APPROACHING IAH...SGR...AND WHARTON. WITH THIS IN MIND AND
TAKING IN CONSIDERATION THE RADAR TRENDS OVER THE PAST HOUR...
DECIDED TO TWEAK THE FLASH FLOOD WATCH AREA TO TAKE OUT BRAZOS AND
BURLESON COUNTIES IN THE FAR WEST AND JACKSON AND WHARTON COUNTIES
IN THE SOUTH. ADDED MONTGOMERY...MAINLY FOR THE WESTERN PART OF
THE COUNTY...AND TRINITY COUNTIES.

TEMPERATURES ARE A BEAR TONIGHT. THE NAM WAS OKAY...BETTER THAN
THE GFS...BUT STILL A BIT OFF IN ITS ORIENTATION OF THE FRONT.
DECIDED TO TAKE THE NAM THROUGH 15Z SUNDAY...THEN EXTRAPOLATE ITS
TEMPERATURES BETWEEN 15Z AND 03Z. THE MODEL LOOKS VERY REASONABLE
IN HOLDING THE FRONT UP A BIT ON SUNDAY AS IT GETS TO THE COAST.
WITH A COUPLE OF SHORTWAVES APPROACHING FROM THE SOUTHWEST IN THE
UPPER FLOW...THIS LOOKS REASONABLE. OF COURSE...HAD TO TWEAK THE
MOISTURE GRIDS AS WELL.

ANOTHER WEATHER ITEM TO FIGURE WILL BE FOG CHANCES. WITH GLS DOWN
TO 1 MILE...DECIDED TO ADD AREAS OF FOG MAINLY TO THE COASTAL
AREAS OF GALVESTON COUNTY.

&&

.PREV DISCUSSION... /ISSUED 608 PM CST SAT JAN 13 2007/

UPDATE...
FRONT HAS MADE LITTLE PROGRESS DURING THE DAY THROUGH OUR
CWA...TOOK 11 HOURS TO TRAVEL THE 30 ODD MILES FROM CLL TO UTS.
CONVECTION THAT EARLIER LED TO FLASH FLOODING IN PARTS OF EWX AREA
NOW LINED UP SOUTHWEST TO NORTHEAST OVER THE WESTERN AND NORTHERN
PORTION OF SOUTHEAST TEXAS...ALONG AND JUST BEHIND THE FRONT.
SATELLITE CLEARLY SHOWING CLOUD TOP COOLING LAST COUPLE OF HOURS. 88D
VWP AND PROFILER DATA SHOW DEEP SOUTHERLY FLOW OF AIR THAT HAS MOISTENED
UP TO AROUND 1.75 PW... WHICH IS AT THE MAXIMUM OBSERVED IN
JANUARY THIS AREA. RADAR INDICATED RAINFALL OF 1 TO 2 INCHES
ALREADY WESTERN COLORADO INTO AUSTIN COUNTY. GIVEN THE SHALLOW
AND SLOWER MOVING FRONT...DEEP TROUGH TO WEST EJECTING MINOR
IMPULSES AND PRESERVING EXTREMELY MOIST SOUTHERLY FLOW
ALOFT...THREAT FOR TRAINING HEAVY RAINFALL SEEMS HIGH TO US.
ISSUED A FLOOD WATCH FOR TONIGHT FOR AREAS WEST AND NORTH OF THE
HOUSTON METRO AREA AND POSSIBLY WILL NEED TO EXTEND EASTWARD
TOMORROW. MADE GRID ADJUSTMENTS BASED ON SLOWER TIMING FOR WIND
SHIFT. NOW LOOKS LIKE THE FRONT WILL BE VERY SLOW TO MOVE THROUGH
HOUSTON PROPER SUNDAY...BEFORE FINALLY MOVING OFF THE COAST BY
EVENING.  30/40

AVIATION...
CONDITIONS EXPECTED TO DETERIORATE RATHER QUICKLY TONIGHT.
ALTHOUGH INITIALLY MVFR AROUND THE BIG AIRPORTS SATURATED AIR AND
SLIGHT COOLING SHOULD LOWER CIGS TO IFR. PERIODS OF RAIN
AND EVENTUALLY THUNDERSTORMS (MIDNIGHT AND BEYOND IAH-SGR-HOU)
BRING VSBY DOWN AS WELL. NO IMPROVEMENT SUNDAY...IN FACT COULD BE
WORSE SHOULD PERSISTENT RAIN CONTINUE AS FRONT WALLOWS THROUGH THE
AREA.  30

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      37  39  30  32  27 / 100  80  80  80  40
HOUSTON (IAH)              48  60  35  37  29 /  70  70  70  80  60
GALVESTON (GLS)            62  67  40  40  35 /  50  60  60  80  60

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...FLASH FLOOD WATCH UNTIL 6 AM CST SUNDAY FOR THE FOLLOWING ZONES:
     AUSTIN...COLORADO...GRIMES...HOUSTON...MADISON...
     MONTGOMERY...TRINITY...WALKER...WALLER...WASHINGTON.

GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 6 AM CST SUNDAY FOR
     THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA
     SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO
     FREEPORT 20 TO 60 NM.

&&

DISCUSSION...40
AVIATION/MARINE...30

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
348 PM CST SAT JAN 13 2007

TXZ163-164-176>179-195>200-210>214-226-227-235>238-141300-
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-
348 PM CST SAT JAN 13 2007

...THREAT OF WINTER WEATHER INCREASING ACROSS PORTIONS OF SOUTHEAST TEXAS
SUNDAY NIGHT INTO WEDNESDAY MORNING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST TEXAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. TRAINING SHOWERS AND
THUNDERSTORMS ACROSS THE WESTERN AND NORTHERN PORTIONS OF SOUTHEAST
TEXAS COULD PRODUCE LOCALLY HEAVY RAINFALL. THIS MAY LEAD TO
LOCALIZED FLOODING.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THERE IS A THREAT FOR RAIN...FREEZING RAIN AND SLEET SUNDAY NIGHT THOUGH
WEDNESDAY MORNING ACROSS MUCH OF INLAND SOUTHEAST TEXAS WHICH COULD
LEAD TO SIGNIFICANT ICE ACCUMULATIONS ACROSS PORTIONS OF SOUTHEAST TEXAS.
A WINTER STORM WATCH MAY BE REQUIRED. SEE THE LATEST SPECIAL WEATHER
STATEMENT ISSUED BY THIS OFFICE FOR DETAILS ON HOW THIS IS EXPECTED
TO EVOLVE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.