FXUS64 KHGX 240533
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1133 PM CST WED DEC 23 2009

.DISCUSSION...
06Z TAF DISCUSSION.

&&

.AVIATION...
MOISTURE AXIS REMAINS OVER SE TX AND HAVE N/S LINE OF STORMS THAT
IS SLOWLY MOVING EAST EMBEDDED WITHIN IT. LLJ REMAINS STRONG AT
40-50KTS SO LLWS MAY PRESENT AN ISSUE FOR SOME TERMINALS. THIS
BAND OF TSRA SHOULD MOVE ACROSS SE TX TERMINALS OVER THE NEXT
HOUR OR TWO. THE MAIN AVIATION PROBLEM FOR THE EARLY MORNING
HOURS WILL BE THE PASSAGE OF A COLD FRONT. THE FRONT IS CURRENTLY
APPROACHING THE I-35 CORRIDOR IN C TX. TIMING THE FRONT HAS IT
REACHING KCLL BY 07Z TO 08Z WHICH IS AN HOUR OR TWO FASTER THAN
WHAT THE PREVIOUS TAF FORECAST SHOWS. MOVED UP THE TIMING OF THE
FRONT AND POSSIBLE LINE OF STORMS ALONG IT BY A COUPLE OF HOURS.
CONVECTION NOW NEAR KSAT MAY INCREASE ALONG THE FRONTAL BOUNDARY
AND PUSH ACROSS SE TX. GUSTY W/NW WINDS WILL BE THE MAIN THREAT
FROM THE STORMS AND FROM THE COLD FRONT. STRONG WNW WINDS WILL
PERSIST BEHIND THE FRONT DURING THE DAY THURSDAY. CIGS NOW AT
MVFR AND AT TIMES IFR LEVELS SHOULD IMPROVE BEHIND THE FRONT.
SKIES SHOULD CLEAR DURING THE NIGHT OF CHRISTMAS EVE WITH STILL
VERY GUSTY WINDS FROM THE NW/N.

39

&&

.PREV DISCUSSION... /ISSUED 1011 PM CST WED DEC 23 2009/ 

UPDATE...
NEW TORNADO WATCH IN EFFECT FOR ALL OF SOUTHEAST TEXAS BUT JACKSON
COUNTY. 

DISCUSSION...
LL JET RIPPING THROUGH THE AREA AND VWP INDICATED A STRONGLY
SHEARED ENVIRONMENT IN PLACE. INSTABILITY HAS BEEN LACKING TO SOME
DEGREE AS INVERSION (PER CRP/ACARS SOUNDINGS) INDICATING ONLY A
THIN SLICE OF CAPE TO WORK WITH SO FAR. EVEN SO A FEW STORMS HAVE
BEEN PUTTING DOWN 1 TO 2 INCH PER HOUR RAINFALL RATES. RADAR
ESTIMATES OF 3 INCHES IN GRIMES/WALLER COUNTY. 

RECENT STORMS ALSO EXHIBITING SOME ROTATION THOUGH SO FAR IT HAS
BEEN WEAK TO MODERATE. WILL BE KEEPING A CLOSE EYE ON STORMS
TRACKING THROUGH THE AREA. HELICITY VALUES OF 170-250 PREVAILING
OVER THE EASTERN 2/3RDS OF THE AREA. 

NEXT WILL BE THE COLD FRONT TO SWEEP IN AFTER MIDNIGHT AND SHOULD
BE EXITING THE AREA 6-8 AM. HODOGRAPH MAY BECOME MORE LINEAR AND
WOULD EXPECT A LINE TO COME IN FROM THE SW AND AND FROM THE NW
MEETING UP OVER THE CENTRAL CWA FILLING IN OVER THE EASTERN HALF
OF THE AREA. SOME WIND DAMAGE POTENTIAL WITH LINEAR MCS/EMBEDDED
BOWING STRUCTURES. 

HAVE ISSUED A WIND ADVISORY FOR THE CWA FOR 6A-6P THURSDAY AS
IMPRESSIVE WINDS ALOFT IN 925-850 LAYER SHOULD MIX DOWN DURING THE
DAY AND EXPECT SUSTAINED WINDS OF 20-25 KNOTS WITH GUSTS NEAR 35
KNOTS AT TIMES.

45/39  

PREV DISCUSSION... /ISSUED 528 PM CST WED DEC 23 2009/ 

DISCUSSION...
00Z TAF DISCUSSION.

AVIATION...
MAIN THREATS WILL BE THE SEVERE WEATHER POTENTIAL MAINLY FOR
KCLL...KUTS AND KCXO. COLD FRONT EXPECTED TO PUSH THROUGH SE TX
AFTER MIDNIGHT TONIGHT WHICH MAY BRING A LINE OF STORMS THROUGH
THE REGION. LATEST THINKING FOR THE TAF AGREES WITH THE PREVIOUS
PACKAGE WITH TSRA AND GUSTY WINDS FROM 06Z TO 12Z THU. THERE MAY
BE SOME POST FRONTAL CLOUDINESS FOR THE LATE MORNING HOURS BUT
LIKELY AT VFR LEVELS. WINDS WILL BE QUITE GUST IN THE AFTERNOON
AS CLOUDS BEGIN TO LIFT AND WINDS MIX DOWN MORE.

39

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      50  51  30  50  31 /  80  40   0   0  10 
HOUSTON (IAH)              52  56  33  52  33 /  80  50   0   0  10 
GALVESTON (GLS)            61  61  40  52  43 /  80  50   0   0  10 

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...WIND ADVISORY FROM 6 AM TO 6 PM CST THURSDAY FOR THE FOLLOWING 
     ZONES: 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.

GM...SMALL CRAFT ADVISORY FROM 3 AM TO 6 PM CST THURSDAY FOR THE 
     FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY.

     SMALL CRAFT ADVISORY FROM 3 AM THURSDAY TO MIDNIGHT CST THURSDAY 
     NIGHT FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE 
     MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND 
     TO FREEPORT OUT 20 NM.

     SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 3 AM CST THURSDAY FOR 
     THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA 
     SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO 
     FREEPORT OUT 20 NM.

     SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST THURSDAY NIGHT 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...45
AVIATION/MARINE...39