Flash Flood and Damaging Winds in Texas, March 28 to 29, 2012

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CORPUS CHRISTI TX
1142 PM CDT TUE MAR 27 2012

.DISCUSSION...NOTE AVIATION DISCUSSION BELOW.

&&

.AVIATION...MVFR/IFR CEILINGS EXPECTED OVERNIGHT. A LINE OF
SHOWERS AND THUNDERSTORMS MAY ENTER THE RIO GRANDE PLAINS
GENERALLY WEST OF STATE ROAD 16 BETWEEN 07-09Z WED. LOCATIONS
AFFECTED BY THIS ACTIVITY MAY EXPERIENCE BRIEF MVFR VISIBILITY
RESTRICTIONS. A TRANSITION TO VFR CONDITIONS EXPECTED DRG THE LATE
MORNING/EARLY AFTN HOURS WED. AFTER 00Z THU...ANTICIPATE AT LEAST
ISOLD SHOWERS/THUNDERSTORMS GENERALLY WEST OF STATE ROAD 16.

&&

.PREV DISCUSSION... /ISSUED 923 PM CDT TUE MAR 27 2012/

DISCUSSION...BOTH THE NAM AND GFS PROG INCREASING POSITIVE
PRESSURE ADVECTION AT THE 1.5 PVU LEVEL ACROSS THE CWA (YET WAVE
REMAINING ABOVE 300MB) FROM WEST TO EAST OVERNIGHT. NAM CORFIDI
VECTORS WOULD ALLOW MCS...CURRENTLY OVER SW TX...TO MOVE TOWARD
SOUTH TX OVERNIGHT. NAM PROGS FAIRLY LOW CIN VALUES CONCOMITANT
WITH CAPE VALUES ABOVE 1000J/KG OVER THE CNTRL/WRN CWA AT 12Z WED.
WILL INTRODUCE LOW POPS TO THE CNTRL/WRN CWA FOR OVERNIGHT. BASED
ON NAM 0-1KM LAPSE RATES/WIND AT 925MB WILL INCREASE ONSHORE FLOW
SLIGHTLY TO THE SCEC CATEGORY OVER AT LEAST THE OFFSHORE COASTAL
WATERS FOR OVERNIGHT. NO OTHER SIGNIFICANT CHANGES.

PREV DISCUSSION... /ISSUED 616 PM CDT TUE MAR 27 2012/

DISCUSSION...SEE AVIATION SECTION BELOW.

AVIATION...VFR CONDITIONS WILL PERSIST THROUGH THE EVENING BEFORE
MVFR CIGS DVLP OVERNIGHT. VCT MAY EXPERIENCE SOME LIGHT FOG
LOWERING THE VSBY TO MVFR LEVELS TOWARD WED MORNING. DUE TO CLOUDS
AND WINDS 5-15KT OVERNIGHT...FOG IS NOT EXPECTED TO BECOME DENSE
NOR WIDESPREAD. VFR CONDITIONS ARE EXPECTED BY MID WED MORNING. WINDS
WILL STRENGTHEN OUT OF THE S AND SE THROUGH WED AFTERNOON.

PREV DISCUSSION... /ISSUED 318 PM CDT TUE MAR 27 2012/

SHORT TERM (TONIGHT THROUGH WEDNESDAY NIGHT)...WEAK SHOWERS
ACROSS THE BRUSH COUNTRY NEAR THE THETA-E RIDGE AXIS WILL WEAKEN
AND DISSIPATE EARLY THIS EVENING WITH LOSS OF HEATING. CONVECTION
FIRING ALONG THE SIERRA MADRE THIS AFTERNOON WILL MOVE TOWARDS THE
U.S. THIS EVENING. CONVECTION MAY APPROACH FAR NORTHWEST WEBB AND
WESTERN LA SALLE COUNTIES...BUT STEERING CURRENTS ARE MORE
FAVORABLE FOR THE CONVECTION TO REMAIN JUST NORTHWEST OF THE CWA
ACROSS THE EDWARDS PLATEAU...AS WELL AS CLOSER TO WEAKNESS ALOFT.
TOMORROW MODELS SHOWING NEGATIVE LOW LEVEL THETA-E ADVECTION
OCCURRING ACROSS THE COASTAL BEND AND VICTORIA CROSSROADS...WITH
THE BETTER MOISTURE AXIS POOLED OVER THE WESTERN BUSH COUNTRY AND
RIO GRANDE PLAINS. THEREFORE ANY ISOLATED SHOWERS DURING THE DAY
ON WEDNESDAY SHOULD BE LOCATED FURTHER WEST THAN TODAY. SHORTWAVE
COMING OUT OF MEXICO LATE WEDNESDAY AFTERNOON AND EVENING SHOULD
ALLOW FOR MORE ACTIVE CONVECTION ALONG AND EAST OF THE SIERRA
MADRE LATE IN THE AFTERNOON. STEERING CURRENTS ARE MORE FAVORABLE
WEDNESDAY EVENING FOR CONVECTION TO MOVE INTO WEBB AND LA SALLE
COUNTIES. LOWS GENERALLY IN THE MID 60S TO LOWER 70S WITH HIGHS
IN THE MID TO UPPER 80S INLAND...UPPER 70S TO LOWER 80S COAST.

LONG TERM (THURSDAY THROUGH TUESDAY)...THE EXTENDED BEGINS WITH
SHOWERS AND THUNDERSTORMS OVER THE CWA...WITH BETTER EMPHASIS OVER
THE WESTERN HALF EARLY THURSDAY...BEFORE EXPANDING FURTHER EAST BY
LATE THURSDAY NIGHT/FRIDAY. PWAT VALUES OF 1.5 INCHES ARE EXPECTED
TO BE IN PLACE AS A H5 TROUGH DIGS SOUTH INTO TEXAS. POSITIVE VORT
MAX TO ENTER OVER THE AREA...IN ADDITION TO DIVERGENCE ALOFT AND
IMPRESSIVE LAPSE RATES IN THE MIDLEVELS...WILL ADD TO THE
THUNDERSTORM ACTIVITY...LEADING TO THE POSSIBILITY OF SOME OF THE
STORMS BECOMING STRONG. OVERALL STORM MOTION COULD LEAD TO SOME
AREAS...PARTICULARLY OVER THE BRUSH COUNTRY...TO RECEIVE BOUNTIFUL
RAIN WITH RAINFALL AMOUNTS AVERAGING BETWEEN 1/2 TO 1 INCH.
DISCREPANCIES IN THE MODELS BEGIN OVER THE WEEKEND...AS THE GFS
CONTINUES TO HAVE LINGERING MOISTURE OVER THE AREA WHILE THE ECMWF
BUILDS A RIDGE. THERE IS ALSO MORE DISAGREEMENT IN THE TIMING OF THE
NEXT SYSTEM TO APPROACH THE AREA. A COLD FRONT IS BEING BROUGHT DOWN
THROUGH THE AREA MONDAY/TUESDAY WITH THE GFS BRINGING IN THE FRONT
ABOUT 12 HOURS EARLIER THAN THE ECMWF. THE GFS HAS ACTUALLY SLOWED
DOWN THE TIMING OF THE FRONT WITH THE 12Z RUN. AS FOR NOW...KEPT
A TREND WITH THE SLOWER EUROPEAN WHICH HAS NOT CHANGED MUCH FROM THE
PAST RUN.

&&

.PRELIMINARY POINT TEMPS/POPS...
CORPUS CHRISTI    68  83  67  80  67  /  10  10  10  30  30
VICTORIA          63  83  63  80  64  /  10  10  10  20  30
LAREDO            72  90  70  86  68  /  30  10  20  40  40
ALICE             68  85  66  82  67  /  10  10  10  40  40
ROCKPORT          69  80  68  77  67  /  10  10  10  20  30
COTULLA           67  86  66  83  65  /  30  10  20  40  50
KINGSVILLE        68  84  67  80  67  /  10  10  10  30  40
NAVY CORPUS       69  81  68  77  68  /  10  10  10  20  30

&&

.CRP WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.

&&

WC/87...SHORT TERM

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CORPUS CHRISTI TX
551 AM CDT TUE MAR 27 2012

GMZ230-235-250-255-270-275-TXZ229>234-239>247-281100-
BAYS AND WATERWAYS FROM BAFFIN BAY TO PORT ARANSAS-
BAYS AND WATERWAYS FROM PORT ARANSAS TO PORT O'CONNOR-
COASTAL WATERS FROM BAFFIN BAY TO PORT ARANSAS OUT 20 NM-
COASTAL WATERS FROM PORT ARANSAS TO MATAGORDA SHIP CHANNEL OUT
20 NM-WATERS FROM BAFFIN BAY TO PORT ARANSAS FROM 20 TO 60 NM-
WATERS FROM PORT ARANSAS TO MATAGORDA SHIP CHANNEL FROM 20 TO
60 NM-LA SALLE-MCMULLEN-LIVE OAK-BEE-GOLIAD-VICTORIA-WEBB-DUVAL-
JIM WELLS-KLEBERG-NUECES-SAN PATRICIO-ARANSAS-REFUGIO-CALHOUN-
551 AM CDT TUE MAR 27 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH TEXAS AND THE MIDDLE
TEXAS COASTAL WATERS.

.DAY ONE...TODAY AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

THERE WILL BE A SLIGHT CHANCE FOR THUNDERSTORMS OVER THE WESTERN
BRUSH COUNTRY WEDNESDAY...THEN A CHANCE OF THUNDERSTORMS ACROSS THE
REMAINDER OF SOUTH TEXAS THURSDAY AND FRIDAY. CLOUD TO GROUND
LIGHTNING STRIKES CAN BE EXPECTED.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.