Severe Thunderstorm Warning 201, NWS Houston/Galveston, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
210 PM CST SAT NOV 20 2004

DISCUSSION...
AT 18Z...A SURFACE BOUNDARY WAS STILL LOCATED ALONG A LCH TO GLS TO
PSX TO LRD LINE. THERE IS A SECOND BOUNDARY ABOUT 20 MILES NORTH OF
I-10 IN WHICH THERE IS A MOISTURE DISCONTINUITY. MOST OF THE
PRECIPITATION HAS FOCUSED ALONG THE MOISTURE DISCONTINUITY. ONLY
SCATTERED ACTIVITY IS OCCURRING SOUTH OF THE MOISTURE BOUNDARY.
PREFER THE GFS SOLUTION OF MOVING THE SFC CONVERGENCE SLOWLY NORTH
OVERNIGHT BEFORE THE BOUNDARY PULLS UP STATIONARY OVER NORTH TEXAS.
THE GFS DEVELOPS A SWATH OF PRECIP ALONG THE BNDRY OVERNIGHT. THE
FLOW ALOFT REMAINS OUT OF THE SOUTHWEST SO A SERIES OF UPPER LEVEL
DISTURBANCES ARE PROBABLE...YET NONE ARE CLEARLY DISCERNABLE ON
SATELLITE OR IN MODEL SOLUTIONS. WILL LOWER POPS TONIGHT FOR AT
LEAST THE SOUTHERN HALF OF THE REGION...KEEPING POPS SCATTERED. ON
SUNDAY...THE BOUNDARY WILL BE NORTH OF OR OVER AT LEAST THE NORTHERN
HALF OF THE REGION...SO AM FAVORING SCT ACTIVITY DUE TO THE LACK OF A
BOUNDARY. THE GFS IS STRONGER WITH BOTH THE DYNAMICS AND MOISTURE
FIELDS AND WILL COMPROMISE BETWEEN THE ETA AND GFS. POP FCST IS
CHALLENGING AND CONFIDENCE IS LOW. TEMPS TONIGHT WILL BE STEADY OR
SLOWLY RISING AS THE BOUNDARY OVER THE GULF PUSHES NORTH.

MOISTURE GETS PULLED WESTWARD TOWARD THE DEEPENING TROUGH OVER
WESTERN AZ. SO FEEL RAIN CHANCES ARE OVERDONE FOR MONDAY AS WELL.
WILL TRIM POPS BACK TO CHANCE. UPPER TROUGH AND SURFACE FRONT CROSS
THE AREA ON TUESDAY AFERNOON. 250 MB WINDS ARE STRONGLY DIVERGENT.
PWS POOL TO AROUND 1.8 INCHES SO IT SEEMS ANOTHER ROUND OF STORMS
IS LIKELY TUES. THE 500 MB TROUGH IS NEGATIVLY TILTED...SO WOULD NOT
BE SURPRISED IF A ROUND OF SEVERE STORMS CROSSED THE AREA.

COOLER AIR WILL FOLLOW IN THE WAKE OF THE FRONT. IN FACT...THE
12Z RUN OF THE GFS IS ADVERTISING LOW TEMPS ON TURKEY DAY IN THE
30S. HAVE TRENDED TEMPS COOLER FOR THU MORNING.

AS OF NOON...COLLEGE STATION RECEIVED 0.70 INCHES OF RAIN. THIS
MAKES IT THE 9TH WETTEST YEAR IN RECORDED HISTORY. WITH MORE RAIN ON
THE WAY...THE ANNUAL TOTAL SHOULD CONTINUE TO CLIMB. 43

&&

.MARINE...
GRADIENT SHOULD BEGIN TO TIGHTEN OVER THE NEXT COUPLE OF DAYS AS
SURFACE SYSTEM DEVELOPS IN THE SOUTHWESTERN U.S. SCATTERED SHOWERS
AND THUNDERSTORMS OVER THE NEXT FEW DAYS WILL CREATE LOCALLY ROUGH
SEAS. WILL INTRODUCE A CAUTION OVER THE GULF WATERS AS THE GRADIENT
WINDS SHOULD BEGIN TO INCREASE OVER THE NEXT 24 HOURS OR SO. 46

&&

.AVIATION...
PRECIPITATION AND CEILINGS PLAYING HAVOC WITH THE TAFS TODAY. LOOKS
LIKE THERE WILL BE A BREAK IN THE PRECIPITATION FOR ALL AREAS WITH
THE EXCEPTION OF COLLEGE STATION THIS AFTERNOON...BUT WE SHOULD SEE
MORE PRECIPITATION...PERHAPS THUNDER LATER TONIGHT AND INTO THE
EARLY MORNING HOURS. 46

&&

.HGX WATCHES/WARNINGS/ADVISORIES...SCEC GULF WATERS.

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 66 74 66 76 66 / 60 60 60 50 50
HOUSTON (IAH)         68 76 67 77 67 / 50 50 40 30 30
GALVESTON (GLS)       72 78 72 78 71 / 40 50 20 20 20

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
435 AM CST SAT NOV 20 2004

TXZ163-164-176>179-195>200-210>214-226-227-235>238-211200-
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-
435 AM CST SAT NOV 20 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST TEXAS.

...HEAVY RAINFALL AND SOME SEVERE THUNDERSTORMS POSSIBLE THIS
WEEKEND AND ON INTO MONDAY AND TUESDAY ACROSS SOUTHEAST TEXAS...

.DAY ONE...TODAY AND TONIGHT
A WARM FRONT PUSHING NORTH ACROSS SOUTHEAST TEXAS ALONG WITH PASSING
UPPER LEVEL DISTURBANCES WILL RESULT IN SCATTERED TO NUMEROUS
SHOWERS AND THUNDERSTORMS. LOCALLY HEAVY RAIN IS POSSIBLE. WITH THE
ALREADY SATURATED GROUNDS...SOME FLOODING MAY BE POSSIBLE.
ALSO...SOME OF THE STORMS MAY BECOME SEVERE. A LONG DURATION FLOOD
WATCH MAY BE ISSUED LATER TODAY.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.
THROUGH TUESDAY...WIDESPREAD RAINFALL ACCUMULATIONS OF 1 TO 3 INCHES
WITH ISOLATED TOTALS APPROACHING 5 INCHES WILL BE POSSIBLE. WITH THE
GROUND ACROSS MUCH OF SOUTHEAST TEXAS NEARLY SATURATED...A FLOOD
THREAT MAY DEVELOP.

SEVERE THUNDERSTORMS MAY ALSO DEVELOP ACROSS SOUTHEAST TEXAS AND THE
ADJACENT COASTAL WATERS SUNDAY ON INTO MONDAY AND TUESDAY. THE MAIN
THREAT WILL PROBABLY BE STRONG DAMAGING WINDS AND ISOLATED TORNADOES.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION MAY BE NEEDED THIS WEEKEND.