Severe Thunderstorm Warning 1, NWS Houston/Galveston, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
958 AM CST SUN FEB 1 2009

.UPDATE...
SCATTERED SHOWERS AFFECTING CHAMBERS COUNTY THIS MORNING WITH
MAJORITY OF REGION UNDER PARTLY CLOUDY SKIES AND LIGHT SOUTHEASTERLIES.
COASTAL TROUGH...WITH WEAK SOUTHERN DISTURBANCES PASSING BY WITHIN
THE SOUTHERN JET BRANCH...WILL KEEP THE CHANCE FOR A PASSING
SHOWER (OVER NEAR COASTAL/SOUTHEASTERN CWA) ALIVE THROUGH THE DAY.
TEMPERATURES STILL EXPECTED TO REACH THE LOWER 70S AS SUNSHINE
WILL OCCASIONALLY PEAK OUT BEHIND BROKEN TO OVERCAST DECKS. COLD
FRONT ENTERING THE PANHANDLE WILL TRAVEL ACROSS THE AREA DURING
THE NOCTURNAL HOURS...INCREASING THE PRE-DAWN CHANCES FOR MORE
WIDESPREAD SHOWERS AND THAT ISOLATED RUMBLE OF THUNDER. 31

&&

.PREV DISCUSSION... /ISSUED 532 AM CST SUN FEB 1 2009/

AVIATION...
FEW SHOWERS WERE AFFECTING THE COASTAL SITES EARLY THIS
MORNING. EXPECT BETTER CHANCES BETWEEN 20Z AND 00Z LATE THIS
AFTERNOON FROM KCXO TO THE COAST. AS THE COLD FRONT PUSHES ACROSS
SOUTHEAST TEXAS TONIGHT...FEEL VERY CONFIDENT THAT MVFR CEILINGS
WILL DEVELOP. TOWARD THE COAST AT KLBX AND KGLS...AREAS OF DENSE
FOG WILL DEVELOP WITH IFR TO LIFR CONDITIONS LIKELY AFTER 03Z AT
KGLS AND 05Z AT KLBX. THERE WILL ALSO BE ABOUT A FOUR HOUR WINDOW
FOR SHOWERS AND THUNDERSTORMS AHEAD OF THE FRONTAL PASSAGE.

40

PREV DISCUSSION... /ISSUED 321 AM CST SUN FEB 1 2009/

DISCUSSION...
AT 08Z...SURFACE HIGH PRESSURE WAS LOCATED OVER THE NORTHERN GULF.
ONSHORE WINDS WERE BRINGING MOISTURE BACK INTO THE REGION. MID
LEVEL CLOUDS WERE MOVING TO THE REGION. CLOUDS SHOULD LOWER AND
THICKEN WITH TIME. UPPER LEVEL DYNAMICS STILL NOT TOO FAVORABLE AS
SOUTHEAST TEXAS LIES IN A RIGHT FRONT QUAD. ALTHO MOISTURE LEVELS
ARE INCREASING...VALUES REMAIN RATHER MEAGER AT LESS THAN AN INCH.
MODELS ARE IN BETTER AGREEMENT WITH REGARD TO RAIN CHANCES TODAY.
AT THIS TIME...IT APPEARS THAT THE DEEPER MOISTURE WILL REMAIN
CLOSE TO THE COAST OR JUST OFFSHORE. WILL LEAVE CHANCE POPS FOR
THE COAST BUT LOWER RAIN CHANCES FURTHER INLAND. TEMPERATURES
SHOULD REMAIN MILD TODAY AND REMAIN SLIGHTLY ABOVE SEASONAL
NORMALS. A COLD FRONT OVER KANSAS WILL MOVE INTO THE REGION
TONIGHT. PREFER THE SLOWER NAM 12 WITH FRONTAL TIMING. UPPER LEVEL
DYNAMICS REMAIN WEAK AND MOISTURE LEVELS STILL NOT THAT GREAT.
FORECAST SOUNDINGS SHOW INSTABILITY INCREASES TONIGHT AND BOTH THE
NAM AND ECMWF SHOW A ROUND OF CONVECTION DEVELOPING ALONG THE
FRONT AROUND 06Z. THE CONVECTION WILL SLIDE SOUTHEAST AND STAY
MAINLY EAST OF I-45. THE 4 KN WRF ALSO SUPPORTS THIS SOLUTION SO
HAVE MAINTAINED HIGHER POPS EAST OVERNIGHT. AREAS OF FOG ALSO
POSSIBLE AHEAD OF THE FRONT...ESPECIALLY NEAR THE COAST. HAVE
ADDED FOG TO THE GRIDS FOR TONIGHT.

SURFACE DEW POINTS WILL FALL CONSIDERABLY ON MONDAY. MODERATE
OFFSHORE WINDS WILL ALSO BRING COOLER TEMPERATURES. WIND AND RH
CONCERNS WILL PRODUCE SOME FIRE WEATHER PROBLEMS ON MONDAY. WILL
ISSUE A FIRE WEATHER WATCH FOR AREAS MAINLY WEST OF I-45 ON
MONDAY. COOLER TEMPERATURES WILL PREVAIL FOR THE FIRST HALF OF THE
WEEK UNDER CLEAR SKIES. ONSHORE WINDS RETURN WEDNESDAY NIGHT.
WARMER TEMPS AND AN INCREASE IN CLOUD COVER CAN BE EXPECTED FOR
THE LATTER HALF OF THE WEEK. MODELS STILL HINTING AT SOME LIGHT
RAIN FOR FRIDAY BUT WILL HOLD OFF MENTIONING FOR NOW. 43

MARINE...
WINDS WILL REACH SCEC CRITERIA BETWEEN 20 AND 60 NM OFFSHORE EARLY
THIS MORNING. MODEL DATA CONSISTENT IN THESE DIMINISHING BY MID
MORNING. TONIGHT THE COLD FRONT WILL WORK ITS WAY TOWARD THE COAST
WITH OFFSHORE WINDS DEVELOPING SOUTH OF FREEPORT AS LOW PRESSURE
DEVELOPS NEAR THE COAST. EXPECT THE ACTUAL FRONT TO MOVE OFF THE
COAST BETWEEN 12Z AND 15Z MONDAY MORNING. WITH STRONG COLD AIR
ADVECTION AND A TIGHT PRESSURE GRADIENT...SMALL CRAFT ADVISORY
CONDITIONS WILL DEVELOP LATER MONDAY MORNING IN THE WAKE OF THE
FRONT. THESE WILL LIFT MONDAY EVENING. ANOTHER FRONT WILL MOVE OFF
THE COAST EARLY WEDNESDAY. A BRIEF PERIOD OF SCA CONDITIONS ARE
POSSIBLE BEHIND THIS FRONT.

40

FIRE WEATHER...
ISSUING A FIRE WEATHER WATCH FOR MONDAY. VERY DRY CONDITIONS WILL
DEVELOP BEHIND A STRONG COLD FRONT MONDAY. WINDS WILL REACH AT LEAST
15 TO 20 MPH THROUGHOUT THE DAY. THE MODEL DEW POINTS WERE FAIRLY LOW
AND MODIFIED THESE A BIT. STILL EXPECT THE RELATIVE HUMIDITY TO GET
BELOW 25 PERCENT FROM LATE MONDAY MORNING TO AROUND SUNSET MAINLY
ALONG AND WEST OF INTERSTATE 45.

40

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      72  47  60  36  68 /  10  40  10   0   0
HOUSTON (IAH)              70  52  61  37  68 /  20  50  30   0   0
GALVESTON (GLS)            67  56  62  47  66 /  30  50  40   0   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...FIRE WEATHER WATCH FROM MONDAY MORNING THROUGH MONDAY AFTERNOON
     FOR THE FOLLOWING ZONES: AUSTIN...BRAZOS...BURLESON...
     COLORADO...FORT BEND...GRIMES...HARRIS...JACKSON...
     MADISON...MONTGOMERY...WALKER...WALLER...WASHINGTON...
     WHARTON.

GM...NONE.
&&

DISCUSSION...31