Severe Thunderstorm Warning 52, NWS Houston/Galveston, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1246 PM CDT MON APR 30 2007

.AVIATION...
MAIN CONCERN FOR THIS AFTERNOON WILL BE ANY THUNDERSTORM
ACTIVITY. LOOKS LIKE CONVECTION EAST OF SAN ANTONIO TO AUSTIN
COULD MAKE IT TO KCLL LATER THIS AFTERNOON. OTHER TERMINALS MAY
SEE PASSING SHOWERS AND A FEW THUNDERSTORMS AS THE ATMOSPHERE
DESTABLIZES WITH DAYTIME HEATING. CAPPING IS STILL STRONG ENOUGH
TO INHIBIT CONVECTION FOR NOW BUT THIS COULD WEAKEN ENOUGH FOR
STORMS TO DEVELOP. WILL AMEND TAF SITES WHEN CONVECTION LOOKS TO
BE MORE CERTAIN AND TIMING OF THE THUNDERSTORM ACTIVITY IS MORE
DIFINITIVE. EXPECT CONVECTION TO BE DONE AFTER 01Z WITH MAINLY
MID LEVEL CLOUDS AFTER THAT. COULD SEE MVFR CONDITIONS IN THE
MORNING WITH LOW CEILINGS AND SOME PATCHY FOG. EXPECT THESE
CONDITIONS TO LIFT AROUND 15-16Z TOMORROW.

39

&&

.PREV DISCUSSION... /ISSUED 1005 AM CDT MON APR 30 2007/

DISCUSSION...
12Z LCH SOUNDING EXPLAINS THE REASONING FOR THE HEIGHTENED AP IN
OUR EASTERN ZONES DUE TO THE STRONG LL INVERSION. INSPECTION OF
THEIR RADAR ALSO SHOWS BEAM BEING TRAPPED UNDER INVERSION SO ITS
A MATTER OF ATMOSPHERIC MIXING TO IMPROVE THIS AP. MIXING MAY BE
ENHANCED BY SHOWERS LATER THIS MORNING INTO THE AFTERNOON
AS...WHERE THE INVERSION IS WEAKER OUT WEST...A FEW SHOWERS HAVE
SPROUTED UP THROUGH WHARTON AND JACKSON COUNTIES. AGREE WITH
MIDNIGHT CREWS THINKING ABOUT COLD POOL PUSH...OR OUTFLOW MAKING
IT TO OUR WESTERN FRINGES...SO WILL INCREASE POPS OUT WEST THROUGH
TODAY. RADAR TRENDS ALSO SHOW DECENT EASTWARD PROGRESSION OF THE
MULTICELLULAR LINE JUST TO THE WEST OF SAN ANTON. SFC ANALYSIS
INDICATES DECENT MOISTURE WITH UPPER 60S TDS AS FAR NORTH AS THE
LAKE SOMERVILLE...DECENT INFLOW PUMPING UP ALREADY HIGH PWS
(BETWEEN 1 AND 2 STD DEV. AT AOA 1.5 BY NOON). NAM12 TARGETS WITH
HIGHEST POPS ALONG WESTERN ZONES...AS WELL. INCREASING CLOUD COVER
WILL REGULATE AFTERNOON HIGHS THIS AFTERNOON BUT MAY WANT TO BUMP
UP HIGHS A DEGREE OR TWO. OTHERWISE...NO MAJOR CHANGES NEEDED IN
THE SHORT TERM.
31

PREV DISCUSSION... /ISSUED 340 AM CDT MON APR 30 2007/

DISCUSSION...
UPPER LOW NOW ACROSS EXTREME SE NEW MEXICO IS STILL EXPECTED TO
CONTINUE MOVING ACROSS THE NORTHERN HALF OF TX THRU WED. WIDESPREAD
SHRA/TSTMS SITUATED ACROSS WEST CENTRAL TX SHOULD DIMINISH IN
INTENSITY AS THEY MOVE EWD...BUT FAIRLY SIGNIFICANT COLD POOL IN THE
WAKE OF THE STORMS SHOULD PUSH THE OUTFLOW AND REMNANT SHRA/TSTMS
INTO W/NW/N PARTS OF THE CWA TODAY. SE PARTS OF THE REGION SHOULD
AGAIN REMAIN MOSTLY DRY. EXPECT ANOTHER ROUND OF PRECIP TO DEVELOP
LATER TONIGHT AND ON TUES AS THE LOW MAKES IT CLOSER TO OUR PARTS.
EXACTLY WHEN/WHERE DEVELOPMENT OCCURS IS DIFFICULT TO DECIPHER AT
THIS POINT DUE TO CONVECTIVE FEEDBACK ISSUES THE 00Z NAM & GFS BOTH
SEEM TO HAVE. THE FAVORED AREA IS OBVIOUSLY A BIT FURTHER EAST OF
WHERE ITS CURRENTLY OCCURRING. NRN PARTS OF THE CWA CLOSER TO THE
LOW/TROF ITSELF SHOULD ALSO SEE A BETTER SHOT THAN THOSE CLOSER TO
THE COAST ON TUES. THE TROF AXIS SHOULD MOVE OFF TO THE EAST DURING
DAY WED BRINGING AN END TO PRECIP CHANCES. ANOTHER SHORTWAVE WILL
PUSH ESE ACROSS OKLAHOMA AND N TX THURS AND THURS NIGHT. ONLY A
SLIGHT CHANCE OF PRECIP ACROSS EXTREME N PARTS OF THE AREA WITH THIS
FEATURE. MID LEVEL RIDGING AND INCREASING THICKNESS VALUES AHEAD OF
THE NEXT WESTERN TROF EXPECTED NEXT WEEKEND LEADING TO WARMING TEMPS
AND DRY WX.

NOTE ABOUT THE HGX RADAR: WE HAVE BEEN SEEING SIGNIFICANT CLUTTER
PROBLEMS THE PAST FEW NIGHTS. EVEN THOUGH WE HAVE HAD A LLVL
INVERSION IN PLACE...ITS DOUBTFUL THAT CAN EXPLAIN EVERYTHING. WE
HAVE GIVEN IT AS MUCH SUPPRESSION AS POSSIBLE HERE IN THE OPS AREA.
TECHS HAVE BEEN NOTIFIED AND WELL SEE IF THEY CAN FIND OUT WHAT MAY
BE GOING ON WHEN THEY ARRIVE LATER THIS MORNING. SORRY FOR ANY
INCONVENIENCE THIS MAY HAVE CAUSED.  47

AVIATION...
AFTER ANOTHER ROUND OF PATCHY FOG THIS MORNING (SOMEWHAT LIMITED BY
THE HIGH CLOUD DEBRIS FROM THE MCS OVER W/C TX)...VFR/MVFR CEILINGS
TO PERSIST THIS AFTERNOON ACROSS MUCH OF SOUTHEAST TEXAS. PCPN CHCS
A LITTLE BETTER TODAY AS THE REMNANTS OF THE MCS MOVE INTO THE AREA
THIS AFTN BUT CONFIDENCE IS LOW ON WIDESPREAD DEVELOPMENT GIVEN THE
CLOUDS ALREADY IN PLACE. LOW CLOUDS (RATHER THAN PATCHY FG) ONCE A-
GAIN TONIGHT/TUE MORNING AS THE WINDS STAY UP. 41

MARINE...
SELY WINDS TO CONTINUE UFN (IT WOULD SEEM) AS THE BULK OF THE STORM
SYSTEMS REMAIN TO OUR NORTH. SOME TIGHTENING OF THE GRADIENT IN THE
OFFING TODAY/TONIGHT AS ONE SYSTEM MOVES ACROSS THE SC PLAINS...BUT
SPEEDS SHOULD SLACKEN A BIT IN ITS WAKE. ANOTHER UPPER TROF TREKING
OVER THE SAME REAL ESTATE TOWARD THE END OF THE WEEK WILL HAVE SELY
WINDS UP A TOUCH ONCE AGAIN. ATTM IT LOOKS LIKE WELL GET AWAY WITH
WIND SPEEDS/SEAS JUST UNDER CAUTION LEVELS THROUGH MUCH OF THE WEEK.
41

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      83  66  78  66  83 /  60  30  60  40  20
HOUSTON (IAH)              85  67  81  67  84 /  30  20  30  20  10
GALVESTON (GLS)            80  70  79  71  79 /  20  10  20  10  10

&&

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

AVIATION/MARINE...39

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1211 PM CDT MON APR 30 2007

TXZ163-164-176>179-195>200-210>214-226-227-235>238-011200-
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-
1211 PM CDT MON APR 30 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST TEXAS.

SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON ACROSS WESTERN
PORTIONS OF SOUTHEAST TEXAS

.DAY ONE...THIS AFTERNOON AND TONIGHT

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON MAINLY
ALONG AND WEST OF A LINE FROM COLLEGE STATION TO BELLVILLE TO WHARTON
TO SARGENT. A LINE OF STRONG TO SEVERE THUNDERSTORMS ACROSS THE HILL
COUNTRY IS MOVING EAST AT 25 TO 30 MPH. THESE STORMS ARE EXPECTED TO
MOVE INTO THE WESTERN PORTIONS OF SOUTHEAST TEXAS THIS AFTERNOON. SOME
OF THE SEVERE THUNDERSTORMS MAY BE CAPABLE OF PRODUCING STRONG DAMAGING
WINDS AND LARGE HAIL. ACTIVITY IS EXPECTED TO WEAKEN LATER THIS AFTERNOON
AND THIS EVENING.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON.