May: Slight Risk Severe Storms Thursday To End The Month

[Ptarmigan]

The line is looking better organized. I think we could see storms while we sleep around 1 AM.

[Andrew]

I thought the outflow boundary would kill off the storms but the dynamics are pretty impressive and kept it going. The line came through College Station with strong winds and a little hail. Radar was a little deceiving but winds were very impressive. Keep an eye out.

[Sockmonkey]

Agree with Ptarmigan.

Those look pretty organized to me...

[srainhoutx]

Not much in the way of cloud cover up here in NW Harris County this morning. The 06Z WRF/NMM is suggesting a short wave disturbance for the afternoon hours across the northern areas as that systems passes. The 00Z Euro is much more aggressive regarding rain chance on Friday for inland areas and the long range WRF is picking up on storms crossing the area in the longer ranges of that model. We'll see what the afternoon bring with the MCS currently over W Central Texas and if we can squeeze out some showers/storms before the frontal boundary drops any further S. The potent upper low is still to our W in the Baja Region and those disturbances offer a forecasting challenges at best as we saw many times this past winter and early spring.

[srainhoutx]

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0755 AM CDT TUE MAY 08 2012

VALID 081300Z - 091200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF S TX...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF FAR W TX AND SRN
NM...

...SYNOPSIS...
MN/DAKOTAS TROUGH EXPECTED TO PROGRESS E INTO WI/UPR MI BY THIS EVE
AND INTO MI/IL EARLY WED AS AZ UPR LOW SETTLES SLOWLY S INTO NW
MEXICO/NRN BAJA CA. DOWNSTREAM FROM THE AZ LOW...MODERATE...DIFLUENT
WSWLY MID/UPR LVL FLOW WILL PREVAIL ACROSS NRN MEXICO AND S TX.

AT THE SFC...COLD FRONT ASSOCIATED WITH THE MN TROUGH HAS MOVED WELL
AHEAD OF UPR SYSTEM. IT WILL CONTINUE TO PROGRESS E ACROSS THE OH
VLY AND NRN/CNTRL APPALACHIANS TODAY/TNGT...AND S/SE ACROSS THE LWR
MS VLY AND ERN/SRN TX. THE BOUNDARY WILL CONTINUE TO SERVE AS A
FOCUS FOR DIURNALLY ENHANCED SHOWERS/STORMS...ALTHOUGH FAIRLY
WIDESPREAD CONVECTION ALSO WILL OCCUR AHEAD OF IT...ESPECIALLY IN S
TX.

...S TX TODAY/TNGT...
MOIST SFC-850 MB E TO SELY FLOW WILL PERSIST ACROSS S TX TODAY AS A
COLD FRONT SETTLES SLOWLY S ACROSS REGION. A LARGE CONVECTIVE
CLUSTER IS PRESENT N OF THE FRONT ATTM ACROSS S CNTRL TX...AND THIS
SYSTEM SHOULD CONTINUE E THROUGH MUCH OF THE DAY...LIMITING LOW LVL
HEATING OVER MUCH OF THE STATE. MORE SUBSTANTIAL HEATING WILL OCCUR
OVER DEEP S TX AND THE LWR RIO GRANDE VLY...AHEAD OF SMALL BUT MORE
INTENSE AREA OF CONVECTION NOW LOCATED SE OF DEL RIO.

COMBINATION OF SUSTAINED MOIST /PW AOA 1.75 INCHES/ UPSLOPE
FLOW...SFC HEATING...AND UPLIFT ASSOCIATED WITH DISTURBANCES IN
DIFLUENT WSWLY UPR JET MAY SUPPORT CLUSTERS OF SUSTAINED
STORMS/EMBEDDED SUPERCELLS ALONG AND S OF THE FRONT...WITH A RISK
FOR SVR WIND...HAIL...AND POSSIBLY A TORNADO OR TWO. OTHER STORMS
MAY FORM OVER THE NRN MEXICO MOUNTAINS. THESE COULD MOVE/DEVELOP E
ACROSS THE RIO GRANDE POSING AN ADDITIONAL RISK OF SVR WEATHER INTO
TNGT.

...FAR W TX/SRN NM THIS AFTN/TNGT...
SCTD TSTMS SHOULD FORM IN MOISTENING...POST-COLD FRONTAL UPSLOPE
ENVIRONMENT ACROSS FAR W TX AND SRN NM LATER TODAY...WHERE 30-40 KT
DEEP SHEAR WILL EXIST TO SUPPORT SUSTAINED STORMS AND EVEN
SUPERCELLS. LOW CLOUDS WILL LIMIT SFC HEATING AND LOW LVL
DESTABILIZATION. NEVERTHELESS...GIVEN STEEP MID LVL LAPSE RATES
...DIFLUENT UPR LVL FLOW E OF AZ UPR LOW...AND POTENTIAL
TERRAIN-INDUCED CIRCULATIONS...A CONDITIONAL RISK WILL EXIST FOR A
FEW STRONGER STORMS WITH SVR HAIL AND LOCALLY DMGG WIND THROUGH
EARLY TNGT.

...TN VLY/GULF CST STATES TODAY...
MODERATE DIURNAL DESTABILIZATION WILL OCCUR TODAY OVER PARTS OF
TN...MS...AL AND GA...ALONG AND AHEAD OF AFOREMENTIONED COLD FRONT.
WITH THE BOUNDARY LAYER FAIRLY MOIST...AND RESIDUAL EML PRESENT
ALOFT...A FEW STORMS MAY YIELD SVR HAIL/LOCALLY DMGG WIND. WHILE THE
ACTIVITY MAY MERGE INTO SMALL CLUSTERS...MODEST DEEP WIND FIELD WILL
LIMIT UPDRAFT STRENGTH/SUSTENANCE...AND DEGREE/ORGANIZATION OF SVR
THREAT.

...CNTRL APPALACHIANS TODAY...
OH VLY COLD FRONT WILL CONTINUE E/SE TO THE WRN SLOPES OF THE CNTRL
APPALACHIANS TODAY...WHERE IT WILL ENCOUNTER REMNANT BACK-DOOR
BOUNDARY STALLED ALONG THE CREST OF THE MOUNTAINS FROM WRN PA TO WRN
NC. LOW LVL MOISTURE WILL REMAIN COMPARATIVELY LIMITED E OF THE
BACK-DOOR FRONT...AND BOUNDARY LAYER MOISTURE WILL DECREASE ALONG
THE WRN SLOPES OF THE MOUNTAINS AS REMAINING WARM SECTOR IS CONSUMED
BY THE MERGING FRONTS. SATELLITE IMAGERY SUGGESTS THAT MUCH OF THE
REGION WILL REMAIN CLOUDY THROUGH THE DAY...LIMITING LOW LVL
DESTABILIZATION. WHILE NUMEROUS SHOWERS AND EMBEDDED TSTMS MAY
OCCUR...PROSPECTS FOR SVR WEATHER APPEAR LOW. A ROGUE TORNADO CANNOT
BE RULED OUT IN ZONE OF BACKED...MOISTENING FLOW JUST E OF THE
BACK-DOOR FRONT OVER PARTS WV...WRN VA AND UPSTATE NC/SC. ANY SUCH
ACTIVITY SHOULD...HOWEVER...REMAIN BRIEF/ISOLD.

...UPR MS VLY TODAY...
VORT MAX MOVING S/SE ACROSS WRN MN ATTM WILL SERVE TO ELONGATE
LARGER-SCALE PROGRESSIVE TROUGH CROSSING REGION. SETUP WILL YIELD
WEAK UNIDIRECTIONAL WLY FLOW ACROSS CNTRL/NRN WI...WHERE
CONSIDERABLE SFC HEATING SHOULD OCCUR BENEATH MID LVL COOL ADVECTION
DOWNSTREAM FROM UPR VORT. SCTD AFTN SHOWERS/STORMS COULD YIELD A
FEW INSTANCES OF SMALL HAIL.

..CORFIDI/GARNER.. 05/08/2012

[srainhoutx]

From NESDIS:

SATELLITE PRECIPITATION ESTIMATES..DATE/TIME 05/08/12 1136Z
SATELLITE ANALYSIS BRANCH/NESDIS---NPPU---TEL.301-763-8678
LATEST DATA USED: GOES-13 1115Z GOES-15 1111Z CW
.
LOCATION...TEXAS...
.
ATTN WFOS...FWD...CRP...EWX...SJT...MAF...
ATTN RFCS...WGRFC...
.
EVENT...HEAVY RAINS
.
SATELLITE ANALYSIS AND TRENDS...CONVECTION CONTINUES TO DEVELOP/EXPAND
ACROSS PORTIONS OF SOUTHWEST TX THIS MORNING IN RESPONSE TO POTENT
SUBTROPICAL UPPER-LEVEL JET STRETCHED ACROSS NRN MEXICO...MAIN CONCERN
IS FOR LOCALIZED AREAS OF PERSISTENT HEAVY RAINS DUE TO CELL TRAINING
AND UPSTREAM CELL REDEVELOPMENT. VWPS OVER THE PAST SEVERAL HRS ACROSS
MUCH OF TX HAVE BEEN NERLY WHICH HAS ALLOWED GOOD LLVL MOISURE TRANSPORT
OF GULF MOISTURE TO BUILD UP ACROSS SW TX FOR CONVECTION TO FEED OFF OF.
ADDITIONALLY...GOES-IR AND PW SOUNDER PRODUCT SATELLITE LOOPS OVER THE
PAST FEW HRS INDICATES DECENT SERLY LLVL MOISTURE TRANSPORT FROM GULF
OF MEXICO. THIS SECOND AND MORE DIRECT TRANSPORT OF GULF MOISTURE ACROSS
DEEP SOUTH TX LIKELY WILL HELP AID ANY STORMS THAT DEVELOPS ALONG THE
SRN EDGE OF THE AREA OF CONVECTION ACROSS SW TX.

WITH BEST MOISTURE TRANSPORT SETUP ALONG THE SRN EDGE OF ONGOING AREA OF
CONVECTION...IT IS THIS AREA THAT IS OF MOST CONCERN FOR CELL TRAINING
AND HEAVIEST RAINFALL OVER THE NEXT 3-6 HRS. WITH THIS IN MIND...GOES-W
WATER VAPOR LOOP ALONG WITH SATELLITE DERIVED UPPER-LEVEL WINDS SEEM TO
INDICATE TROUGH LOCATED FROM SRN CA/SRN AZ TO JUST OFFSHORE OF BAJA CA
IS STILL IN THE PROCESS OF DIGGING. AS A RESULT...TROUGH IS EXPECTED TO
SINK FURTHER SOUTH THUS FORCING SUBTROPICAL JET TO ALSO TREND FURTHER S.
AREA OF BEST UPPER-LEVEL DIFFLUENCE FROM JET EXIT REGION LIKELY TO SETUP
CLOSER TO 30N 100W. THIS WOULD ALL SEEM TO INDICATE THAT CONVECTION
LIKELY TO SLIDE SWD DURING THE MORNING/EARLY AFTERNOON AND HEAVIEST
RAINS WOULD BE ALONG THE S SIDE...WHERE MOISTURE TRANSPORT IS GREATEST.
.
AN ANNOTATED SATELLITE GRAPHIC SHOWING THE HEAVY PRECIPITATION THREAT AREA
SHOULD BE AVAILABLE ON THE INTERNET ADDRESS LISTED BELOW IN APPROXIMATELY
10-15 MINUTES.
.
SHORT TERM OUTLOOK VALID 1130-1530Z...MEDIUM CONFIDENCE FACTOR IN SHORT
TERM OUTLOOK...CONVECTION ACROSS SW TX EXPECTED TO CONTINUE TO THRIVE
THROUGH THE MORNING HRS ACROSS SW TX AND HEAVY RAINS ARE LIKELY GIVEN WELL
ABOVE AVG LLVL MOISTURE AND STRONG UL DYNAMIC FORCING FROM SUBTROPICAL
JET STRETCHED ACROSS NRN MEXICO. PRESENCE OF MODEST NERLY FLOW SHOULD AID
IN THE SLOW MOVING NATURE OF CONVECTION AND BACK-BUILDING OF CELLS FOR
LOCALIZE CELL TRAINING. GREATEST THREAT OF HEAVY RAIN POTENTIAL LIKELY
TO BE ALONG THE SRN EDGE OF CONVECTION AREA AND THIS IS ANTICIPATED TO
SLOWLY SLIDE SWD OVER THE NEXT SEVERAL HRS TOWARD BETTER LVLL MOISTURE
CONVERGENCE DUE TO NOSE OF SUBTROPICAL JET DROPPING SWD AS TROUGH OVER
ERN PACIFIC INTENSIFIES.

[srainhoutx]

We'll need to watch the storms from Del Rio, Eagle Pass and on down toward Laredo. The models haven't picked up on this disturbance very well and the general movement is E and may become an issue for parts of SE TX later in the afternoon/evening. We will see.

[srainhoutx]

MESOSCALE DISCUSSION 0757
NWS STORM PREDICTION CENTER NORMAN OK
1044 AM CDT TUE MAY 08 2012

AREAS AFFECTED...DEEP SOUTH TEXAS

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 081544Z - 081645Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...SHORT TERM CONVECTIVE TRENDS REMAIN UNCERTAIN...BUT
CURRENT INTENSIFICATION OF A STORM TO THE SOUTH OF LAREDO MAY
REQUIRE A WATCH SHORTLY.

DISCUSSION...WITHIN AN AREA LARGE-SCALE ASCENT DOWNSTREAM OF THE
SOUTHWESTERN U.S. CLOSED LOW AND UPPER TROUGH EXTENDING SOUTHWARD
THROUGH BAJA...SCATTERED THUNDERSTORM ACTIVITY CONTINUES TO
GRADUALLY SPREAD EASTWARD THROUGH THE LOWER RIO GRANDE VALLEY TOWARD
LOWER TEXAS COASTAL AREAS. ACTIVITY EAST OF THE RIVER HAS BEEN
GENERALLY CONFINED TO THE COOL SIDE OF A SOUTHWARD ADVANCING COLD
FRONT...WITH RESIDUAL WARMER ELEVATED MIXED LAYER AIR STILL
INHIBITIVE OF BOUNDARY LAYER BASED STORM DEVELOPMENT TO THE SOUTH.
ADDITIONALLY...LATEST RAPID REFRESH IS SUGGESTIVE THAT LOWER/MID
TROPOSPHERIC WARM ADVECTION MAY WEAKEN ACROSS THE REGION DURING THE
17-19Z...WHICH COULD RESULT IN DIMINISHING CONVECTIVE TRENDS.
SO...NEAR TERM SEVERE WEATHER POTENTIAL REMAINS UNCLEAR.

HOWEVER...RECENT INTENSIFICATION OF A CELL IS UNDERWAY OFF THE
HIGHER TERRAIN TO THE SOUTHWEST OF LAREDO. THIS APPEARS TO THE
SOUTH OF THE FRONT...AND WEAK WESTERLY DEEP LAYER MEAN FLOW COULD
AID PROPAGATION INTO A DESTABILIZING ENVIRONMENT EAST OF THE
RIVER...WHERE ADDITIONAL SURFACE HEATING COULD CONTRIBUTE TO
WEAKENING OF INHIBITION AND FURTHER INTENSIFICATION.

..KERR.. 05/08/2012


ATTN...WFO...CRP...EWX...BRO...

[srainhoutx]

Code: Select all

BULLETIN - IMMEDIATE BROADCAST REQUESTED
   SEVERE THUNDERSTORM WATCH OUTLINE UPDATE FOR WS 267
   NWS STORM PREDICTION CENTER NORMAN OK
   1100 AM CDT TUE MAY 8 2012
   
   SEVERE THUNDERSTORM WATCH 267 IS IN EFFECT UNTIL 700 PM CDT
   FOR THE FOLLOWING LOCATIONS
   
   TXC007-013-025-047-057-123-127-131-163-175-215-239-247-249-255-
   261-273-283-285-297-311-321-323-355-391-409-427-469-479-493-505-
   507-090000-
   /O.NEW.KWNS.SV.A.0267.120508T1600Z-120509T0000Z/
   
   TX 
   .    TEXAS COUNTIES INCLUDED ARE
   
   ARANSAS              ATASCOSA            BEE                 
   BROOKS               CALHOUN             DEWITT              
   DIMMIT               DUVAL               FRIO                
   GOLIAD               HIDALGO             JACKSON             
   JIM HOGG             JIM WELLS           KARNES              
   KENEDY               KLEBERG             LAVACA              
   LA SALLE             LIVE OAK            MATAGORDA           
   MAVERICK             MCMULLEN            NUECES              
   REFUGIO              SAN PATRICIO        STARR               
   VICTORIA             WEBB                WILSON              
   ZAPATA               ZAVALA            

[MontgomeryCoWx]

75 dbz cloudtops south of Laredo....

[Ptarmigan]

NWS Houston Forecast

Code: Select all

Tonight: Showers and thunderstorms likely, mainly between 7pm and 1am. Mostly cloudy, with a low around 68. Calm wind. Chance of precipitation is 60%.

Wednesday: A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a high near 84. North wind between 5 and 10 mph. 

Wednesday Night: Mostly cloudy, with a low around 65. Northeast wind around 5 mph.

I wouldn't be surprised if it rains past 1AM. I think more storms will fire up in Central Texas.

[srainhoutx]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
332 PM CDT TUE MAY 8 2012

.DISCUSSION...
FIRST IT LOOKS LIKE THE MAIN SEVERE THREAT WILL BE FARTHER SOUTH
INTO S TX AND COASTAL WATERS. WILL BE DROPPING SEVERE WATCH 267
SHORTLY FOR JACKSON/MATAGORDA SHORTLY.

STRONG OUTFLOW BOUNDARY FROM CONVECTION LAST NIGHT AND YESTERDAY
HAS PUSHED OFF THE COAST AND SEEMS TO BE TRIGGERING THUNDERSTORM
ACTIVITY OVER S TX THROUGH THE COASTAL BEND. WITH DAY TIME
HEATING...SEA BREEZE BOUNDARY HAS FORMED ALONG THE COAST AND HAS
INITIATED DEEP CONVECTION ALONG IT AS WELL. MAIN SEVERE THREAT
SEEMS TO BE WHERE HIGHER MOISTURE EXISTS SOUTH OF THE OUTFLOW IN S
TX BUT WILL HAVE TO MONITOR LARGE SCALE ASCENT FROM A JET STREAK
MOVING ACROSS THE AREA TONIGHT. ALIGNED POPS FOR ONGOING TRENDS
THIS AFTERNOON AND INCREASED THUNDERSTORM CHANCES OVERNIGHT AS JET
STREAK MOVES OVER THE AREA AND SUPPORTS MORE SCT THUNDERSTORM
ACTIVITY. EXPECT MOST OF THIS ACTIVITY TO END BY MIDNIGHT.

STILL KEEP 40 POPS FOR SE TX TOMORROW. LATEST SFC ANALYSIS HAS
FRONTAL BOUNDARY FROM ARKLATEX THROUGH W C TX THIS AFTERNOON.
FRONT SHOULD SLOWLY PUSH INTO THE AREA OVERNIGHT AND TOMORROW. NAM
HINTS AT STRONGER FRONTOGENETIC LIFT ALONG THE FRONT AND THE 850MB
FRONT TOMORROW SO COULD SEE SOME ELEVATED CONVECTION AND SHOWERS.
SLIGHT DRIER AIRMASS SHOULD ARRIVE LATE WED BUT BE SHORT LIVED.
MODELS IN DECENT AGREEMENT WITH NEXT APPROACHING UPPER LOW AND
INCREASING RETURN FLOW THUR INTO THUR NIGHT.

UPPER LOW ON WATER VAPOR IMAGERY NOW OVER THE DESERT SW WILL TAKE
ITS SWEET TIME PUSHING EAST ACROSS THE S ROCKIES INTO TX BY FRI.
DEEP MOISTURE WILL RETURN TO SE TX WITH PRECIP WATER VALUES
REACHING AROUND 1.7 TO 1.8 INCHES BY FRI MORNING PER BOTH GFS/NAM.
BY 12-18Z FRI LARGE SCALE ASCENT WILL BE MAXIMIZED BY SPLITTING
JET FLOW ALONG WITH PVA AND Q VECTOR DIVERGENCE. BASICALLY PICK A
PARAMETER TO DIAGNOSE LIFT AND IT WILL BE PRESENT OVER SE TX
DURING THIS TIME. GIVEN HIGH MOISTURE CONTENT WITH PW VALUES JUST
UNDER 2 STANDARD DEVS ABOVE NORMAL...WILL HAVE TO MONITOR FOR
HEAVY RAINFALL POTENTIAL ESPECIALLY IS MORE RAINFALL OCCURS THE
NEXT COUPLE OF DAYS IN ADVANCE OF THIS SYSTEM. FLOOD WATCH MAY BE
NEEDED IN THE COMING DAYS. THE GFS AND ECMWF ARE IN BETTER
AGREEMENT WITH A SLOW MOVING SYSTEM. POPS WERE PUSHED HIGHER FRI
NIGHT INTO SAT AS THE UPPER LOW SLOWLY EXITS. MAY SEE SOME
LINGERING CONVECTION AS PIECES OF VORTICITY ROTATE AROUND THE
UPPER LOW.

EARLY NEXT WEEK THE FORECAST WILL REMAIN DRY ALTHOUGH COULD MAKE
THE CASE FOR 20 POPS DURING THE SUN-TUE TIME FRAME NEXT WEEK.
UPPER LEVEL FLOW REMAINS SOMEWHAT PROGRESSIVE WITH NW-W FLOW.
COULD SEE A COUPLE OF WEAK SHORTWAVES ROTATE THROUGH TX BUT GFS
AND ECMWF BOTH HAVE VARYING SOLUTIONS SO WILL NOT TRY TO PINPOINT
EXACT TIMING OF THESE FEATURES.

[srainhoutx]

The 00Z WRF/NMM suggests showers and elevated storms tomorrow. That model also suggests lingering storm for Friday as the boundary lifts N. Well will see…

[Ptarmigan]

Friday looks to be a rainy day. I wonder about tonight.

[Katdaddy]

From this mornings Hazardous Weather Outlook:

AN UPPER LOW WILL MOVE ACROSS THE STATE THURSDAY NIGHT THROUGH
EARLY SATURDAY. THUNDERSTORM COVERAGE IS EXPECTED TO INCREASE FROM
WEST TO EAST THURSDAY NIGHT AND PERSIST THROUGH THE DAY FRIDAY.
MODEL GUIDANCE AT THIS TIME SHOWS THAT THE MAIN THREAT WILL BE
LOCALLY HEAVY RAINFALL MAINLY TOWARD AND ALONG THE COAST. BECAUSE
OF THE UNCERTAINTY OF THE MODEL FORECASTS...WILL CONTINUE TO
MONITOR FOR THE POSSIBILITY OF A FLOOD WATCH. A BREAK IN THE
RAINFALL IS LIKELY BY LATE SATURDAY OR EARLY SUNDAY WITH THE UPPER
LOW MOVING OUT OF THE STATE. ANOTHER CHANCE FOR ISOLATED
THUNDERSTORMS IS POSSIBLE LATE MONDAY INTO TUESDAY.

[srainhoutx]

Morning e-mail from Jeff:

Meso scale features playing havoc with forecast. Strong storm system will move into the area Thursday night-Saturday with heavy rainfall and severe weather possible.



Weak cool front slipped through the area late yesterday afternoon which helped to usher in a drier air mass from the north and kept all of the thunderstorms activity on Tuesday confined to our SW and right along the coastal seabreeze front. Air mass has continued to slowly dry overnight with dewpoints now into the low to mid 60’s areawide. Weak short wave over central TX is producing a small area of rain showers east of Austin and SW of College Station currently with a movement toward the east, this feature will be over SE TX today. Not overly impressed with rain chances for today and feel the current cloudy conditions will limit heating along with weak northerly flow will keep instability on the low side. Also there is no real good focus for surface convergence with the front now south of the area. Will go with 20-30% for a few showers as the central TX disturbance moves across.



Air mass dries even more tonight with weak ridging developing over the region for Thursday ahead of the strong closed Baja low. As this low begins to eject eastward early Thursday downstream height falls will result in low pressure forming over the Rio Grande plains which will in turn start to pull the frontal boundary northward as southerly flow develops. Moisture will rapidly increase over S TX Thursday with PWs climbing to near 2.0 inches by Thursday evening. Strong heating and moisture influx, combined with a strong short wave rotating around the east side of the upper low into NE MX along with increasing strong upper level divergence all point to rapid and strong thunderstorm formation over NE MX and the Rio Grande plains Thursday afternoon. Storms should quickly grow upscale with favorable 40-50kts of SW shear into a large thunderstorm complex (MCS) across SC TX Thursday evening. Severe weather appears at least possible with this feature as downstream instability over the coastal bend and influx of rich Gulf air mass will be in place. MCS should move E to ESE overnight Thursday into Friday morning and will likely approach/move into our W/SW counties before sunrise. Not sure how far east this complex will make it as this depends greatly on how quickly the air mass over SE TX moistens on Thursday night and how fast the offshore frontal boundary lifts northward. It is very possible that this complex feeds ESE or even SE offshore along the frontal boundary and into the NW Gulf keeping all the moisture offshore….this has been hinted at over the past few model runs with the highest QPF offshore. However we are dealing with the meso scale and little is certain this far out…but there is a fair amount of uncertainty in the Friday-Saturday forecast.



At some point we should see some decent thunderstorm coverage as the main upper air system moves across the state Friday-Saturday, but as mentioned above the meso scale with its large thunderstorm complexes may throw a wrench in that thinking. Will really have to wait to see how things play out Thursday night/Friday morning before becoming more confident in additional rains Friday afternoon. With a slightly slower movement of the main upper level storm…rain chances will likely need to be carried over into Saturday at least through the morning hours.

[unome]

I could take this kind of weather all summer long - enough rain, enough sun, not 100+

awesome Houston area satellite/options http://www.ssd.noaa.gov/goes/east/wfo/hgx.html

[unome]

could be

http://www.hpc.ncep.noaa.gov/national_f ... .php?day=1

http://www.hpc.ncep.noaa.gov/national_f ... .php?day=2

http://www.hpc.ncep.noaa.gov/national_f ... .php?day=3

[srainhoutx]

It appears there may be some convective feedback issues with the GFS/NAM and that issue may lead to the further offshore focusing of heavier rainfall. The 12Z Canadian does suggest heavy showers/storms across all of SE TX and is a tad slower with the upper low moving out of W Texas on Friday. We will see.

[srainhoutx]

The latest QPF forecast update is out and I suspect we in SE TX may see a Flood Watch hoisted like the one just re issued for the Austin/San Antonio WFO...

FLOOD WATCH
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
302 PM CDT WED MAY 9 2012

...A FLASH FLOOD WATCH IS IN EFFECT FOR ALL OF SOUTH CENTRAL TEXAS
FROM 6 PM THURSDAY EVENING UNTIL NOON FRIDAY...

.AN UPPER LEVEL LOW PRESSURE SYSTEM ACROSS NORTHERN MEXICO WILL
MOVE EASTWARD INTO WEST TEXAS TONIGHT. THE UPPER LOW WILL CONTINUE
TO MOVE ACROSS TEXAS THURSDAY AND FRIDAY BEFORE MOVING INTO EAST
TEXAS ON SATURDAY. THE UPPER LEVEL LOW WILL COMBINE WITH A MOIST
AND UNSTABLE AIRMASS ACROSS SOUTH CENTRAL TEXAS TO PRODUCE SHOWERS
AND THUNDERSTORMS ACROSS THE REGION. CHANCES FOR RAIN WITH THIS
SYSTEM WILL INCREASE FROM WEST TO EAST BEGINNING WEDNESDAY NIGHT
AND SPREAD TO MUCH OF THE REGION BY THURSDAY AFTERNOON. NUMEROUS
SHOWERS AND THUNDERSTORMS ARE EXPECTED THURSDAY EVENING THROUGH
FRIDAY MORNING...BEFORE DECREASING FROM WEST TO EAST FRIDAY
AFTERNOON.

IN ADDITION TO THE PROLONGED PERIOD OF RAIN...SOME OF THE THUNDERSTORMS
WILL PRODUCE HEAVY RAINFALL. SOILS HAVE BEEN MOISTENED FROM RAINFALL
EARLIER THIS WEEK...SO ADDITIONAL RAINFALL WILL BE QUICK TO RUNOFF
AND MAY LEAD TO FLASH FLOODING...AS WELL AS FLOODING OF SMALL
CREEKS AND STREAMS.

RAINFALL TOTALS FOR WEDNESDAY NIGHT THROUGH FRIDAY EVENING WILL
AVERAGE 2 TO 4 INCHES. ISOLATED TOTALS HIGHER THAN 4 INCHES ARE
POSSIBLE.


TXC013-019-021-029-031-053-055-091-123-127-137-149-163-171-177-
187-209-255-259-265-271-285-287-299-323-325-385-453-463-465-491-
493-507-100500-
/O.NEW.KEWX.FF.A.0005.120510T2300Z-120511T1700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
ATASCOSA-BANDERA-BASTROP-BEXAR-BLANCO-BURNET-CALDWELL-COMAL-
DEWITT-DIMMIT-EDWARDS-FAYETTE-FRIO-GILLESPIE-GONZALES-GUADALUPE-
HAYS-KARNES-KENDALL-KERR-KINNEY-LAVACA-LEE-LLANO-MAVERICK-MEDINA-
REAL-TRAVIS-UVALDE-VAL VERDE-WILLIAMSON-WILSON-ZAVALA-
INCLUDING THE CITIES OF...PLEASANTON...BANDERA...BASTROP...
SAN ANTONIO...BLANCO...BURNET...LOCKHART...NEW BRAUNFELS...
CUERO...CARRIZO SPRINGS...ROCKSPRINGS...LA GRANGE...PEARSALL...
FREDERICKSBURG...GONZALES...SEGUIN...SAN MARCOS...KARNES CITY...
BOERNE...KERRVILLE...BRACKETTVILLE...HALLETTSVILLE...GIDDINGS...
LLANO...EAGLE PASS...HONDO...LEAKEY...AUSTIN...UVALDE...DEL RIO...
GEORGETOWN...FLORESVILLE...CRYSTAL CITY
302 PM CDT WED MAY 9 2012

...FLASH FLOOD WATCH IN EFFECT FROM THURSDAY EVENING THROUGH
FRIDAY MORNING...

THE NATIONAL WEATHER SERVICE IN AUSTIN/SAN ANTONIO HAS ISSUED A

* FLASH FLOOD WATCH FOR THE FOLLOWING COUNTIES IN SOUTH CENTRAL
TEXAS...ATASCOSA...BANDERA...BASTROP...BEXAR...BLANCO...
BURNET...CALDWELL...COMAL...DEWITT...DIMMIT...EDWARDS...
FAYETTE...FRIO...GILLESPIE...GONZALES...GUADALUPE...HAYS...
KARNES...KENDALL...KERR...KINNEY...LAVACA...LEE...LLANO...
MAVERICK...MEDINA...REAL...TRAVIS...UVALDE...VAL VERDE...
WILLIAMSON...WILSON AND ZAVALA.

* FROM THURSDAY EVENING THROUGH FRIDAY MORNING

* AVERAGE STORM TOTAL RAINFALL AMOUNTS OF 2 TO 4 INCHES WITH
ISOLATED TOTALS HIGHER THAN 4 INCHES POSSIBLE.

* PERIODS OF RAIN...HEAVY AT TIMES...WILL PRODUCE FLASH FLOODING
OF NORMALLY DRY CREEK BEDS...POOR DRAINAGE AREAS AND LOW WATER
CROSSINGS. URBANIZED AREAS INCLUDING LOCATIONS IN AND AROUND THE
AUSTIN AND SAN ANTONIO METRO AREAS CAN EXPECT RUNOFF TO MAKE
SOME ROADWAYS IMPASSABLE. THE FLASH FLOOD IMPACT WILL BE HIGHEST
FROM THURSDAY NIGHT INTO FRIDAY MORNING.

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
359 PM CDT WED MAY 9 2012

GMZ330-335-350-355-370-375-TXZ163-164-176>179-195>200-210>214-226-
227-235>238-102100-
AUSTIN-BRAZORIA-BRAZOS-BURLESON-CHAMBERS-COLORADO-FORT BEND-
GALVESTON-GALVESTON BAY-GRIMES-HARRIS-HOUSTON-JACKSON-LIBERTY-
MADISON-MATAGORDA-MATAGORDA BAY-MONTGOMERY-POLK-SAN JACINTO-
TRINITY-WALKER-WALLER-WASHINGTON-
WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM-
WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM-
WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM-
WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM-WHARTON-
359 PM CDT WED MAY 9 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST TEXAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT

HAZARDOUS WEATHER IS NOT EXPECTED TONIGHT.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

AN UPPER LOW WILL MOVE ACROSS THE STATE THURSDAY NIGHT THROUGH
SATURDAY. THUNDERSTORM COVERAGE IS EXPECTED TO INCREASE FROM WEST
TO EAST THURSDAY NIGHT AND PERSIST THROUGH THE DAY FRIDAY. A
SQUALL LINE OF STORMS MAY BE POSSIBLE AND COULD BECOME SEVERE.
DAMAGING STRAIGHT LINE WINDS WILL BE THE PRIMARY THREAT. MODEL
GUIDANCE CONTINUES TO HIGHLIGHT THE THREAT FOR LOCALLY HEAVY
RAINFALL MAINLY TOWARD AND ALONG THE COAST. RAINFALL AMOUNTS OF 2
TO 3 INCHES WITH ISOLATED 5 INCHES WILL BE POSSIBLE MAINLY SOUTH
OF INTERSTATE 10. GENERALLY 1 TO 2 INCHES OF RAINFALL WILL BE
POSSIBLE NORTH OF INTERSTATE 10. A FLOOD WATCH MAY NEED TO BE
ISSUED TOMORROW MORNING FOR SOUTHEAST TEXAS. A BREAK IN THE
RAINFALL IS LIKELY BY LATE SATURDAY OR EARLY SUNDAY WITH THE UPPER
LOW MOVING OUT OF THE STATE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED THURSDAY NIGHT THROUGH FRIDAY.