May: Slight Risk Severe Storms Thursday To End The Month

[Katdaddy]

An active weather day ahead and so it begins:

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 270
NWS STORM PREDICTION CENTER NORMAN OK
545 AM CDT THU MAY 10 2012

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

SOUTH CENTRAL AND DEEP SOUTH TEXAS
COASTAL WATERS

EFFECTIVE THIS THURSDAY MORNING AND AFTERNOON FROM 545 AM UNTIL
100 PM CDT.

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70
STATUTE MILES EAST AND WEST OF A LINE FROM 45 MILES WEST
NORTHWEST OF JUNCTION TEXAS TO 5 MILES WEST SOUTHWEST OF
BROWNSVILLE TEXAS. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU0).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

DISCUSSION...ELEVATED TSTMS...INCLUDING A FEW SUPERCELLS... EXPECTED
TO INCREASE IN COVERAGE OVER THE LWR RIO GRANDE VLY OF TX THROUGH
MIDDAY AS WAA...LOW LVL MOISTURE TRANSPORT...AND UPR DIVERGENCE
INCREASE DOWNSTREAM FROM UPR LOW NOW APPROACHING FROM N CNTRL
MEXICO. DEEP WIND PROFILES...ALREADY ADEQUATE FOR SUPERCELLS...WILL
STRENGTHEN LATER THIS MORNING. COUPLED WITH QUALITY OF MOIST INFLOW
/PW 1.25-1.75 INCHES/ AND THE LIKELIHOOD THAT UPDRAFTS WILL BECOME
MORE NEARLY SFC-BASED WITH TIME...SRN AND PERHAPS CNTRL PARTS OF THE
WATCH MAY REQUIRE UPGRADE TO TORNADO LATER THIS MORNING.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM
MOTION VECTOR 24020.

[srainhoutx]

Nice to see some much need rain near our hunting lease...

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
704 AM CDT THU MAY 10 2012

TXZ219-220-101245-
ATASCOSA-FRIO-
704 AM CDT THU MAY 10 2012

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN ATASCOSA AND
SOUTHEASTERN FRIO COUNTIES UNTIL 745 AM CDT...

AT 702 AM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
STRONG THUNDERSTORM 13 MILES NORTH OF FOWLERTON...OR 17 MILES
SOUTHWEST OF CHARLOTTE...MOVING NORTHEAST AT 30 MPH.

HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 40 MPH ARE
EXPECTED WITH THIS STORM.

LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...
CHARLOTTE...
JOURDANTON...
PLEASANTON...
GOLDFINCH...
HINDES...
DAVIS...
DOBROWOLSKI...
AMPHION...

[srainhoutx]

Morning e-mail from Jeff:

***Heavy rainfall and severe weather possible this afternoon-Friday night***



Impressive upper level storm system over northern MX has begun its assault on the state of TX this morning. Radar already show widespread deep convection developing over SW/W TX on the leading edge of lift on the eastern flank of the storm system and returning SE flow off the Gulf of Mexico. At the surface a weak frontal boundary remains stalled along the lower to middle TX coast then ENE toward the central Gulf coast. Strong upper level forcing spreading eastward out of MX today will help develop a frontal wave over southern TX today with a warm front backing northward and likely inland across SE TX tonight. Short term models indicate that thunderstorm formation is at least possible today as the boundary returns northward over the area and/or SW TX storms move into the region from the WSW by mid afternoon. Still a decent amount of dry air at the surface over this area compared to areas to our SW so once again as seen on Tuesday what looks impressive to our west may weaken as it approaches…with that said, the current air mass will be undergoing fairly rapid modification today.



Main event looks on tap for tonight as either one or more convective complexes develop over NE MX/SW TX and race eastward toward the area. Strong upper level divergence on the eastern flank of the upper level system combined with 40-55kt of shear, good SE low level flow, and high moisture levels (PWS nearing 1.7-1.9 inches) all support vigorous thunderstorm formation. Uniform shear inland suggest scattered thunderstorms will grow rapidly upscale into a large MCS feature and progress E/ESE toward the TX coast…this is supported by the TX Tech meso WRF model showing a large MCS plowing across much of the area between midnight and 800am Friday. This model is showing a fairly strong “bowing” signal and with favorable wind energy in the mid levels, wind damage looks possible along the leading edge of this line.



Meso scale processes will drive the weather post 600am Friday as the potential for a large thunderstorm complex to be ongoing over the region at that time. Models time to re-develop convection behind the initial complex, but this is highly uncertain as the air mass will likely be heavily worked over and stabilized. However the slow moving upper level system will still be located NW of the region placing the area under favorable dynamics aloft so it will not take much to get things going.



Severe Threat:

Biggest uncertainty is how quickly and far north the offshore surface boundary moves determining how far inland a juicy air mass penetrates. Models have been wanting to hold this feature near the coast and even offshore, but recent guidance has trended more northward with the track of the main upper level storm which will likely help pull the boundary further inland across more of SE TX. Another concern is the potential for convection this afternoon either developing on the boundary or approaching from the west to help push the boundary back southward due to cool storm outflows. Feel the boundary will push inland later today and possible reach I-10 tonight. SPC has our SW counties outlooked for severe weather tonight and it is very possible that this area will need to be expanded to include more of the region. My current thinking is area SW of a line from College Station to The Woodlands to High Island will have some degree of severe threat tonight. Wind damage is likely the main severe mode with any type of linear/bowing thunderstorm complex although low level shear will be enhanced near the frontal boundary across the region. Feel any threat of supercells and tornadoes will be greatest this afternoon and evening south of Matagorda Bay over S TX where low level shear is strongest and instability is greatest.



Heavy Rainfall:

Widespread rainfall of 1-3 inches appears likely which most areas will be able to handle without major problems. Concern comes with the potential for any additional develop on Friday behind the main line or the possibility that the complex of storms slows as it nears the coast and stalls. Moisture levels will be extremely high and the upper levels will have good venting along with a vigorous feed of deep moisture off the Gulf. This all supports high hourly rainfall rates in the stronger storms with potential for a few 2-3 inch amounts in an hour or less. Urban areas may have some issues with that kind of rainfall rate. Flash Flood Guidance is fairly high over the region given the recent dry spell and current QPF forecast are not exceeding those values, so the NWS has decided to hold off on a Flash Flood Watch for now. Trends today may require a watch be issued later today or this evening.



Day 1 (Today) Severe Weather Outlook:

[srainhoutx]

The frontal boundary is beginning to retreat slowly N across the Metro Area the morning...

[srainhoutx]

Moderate Risk may be ahead as memtioned in the SPC Update:

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0758 AM CDT THU MAY 10 2012

VALID 101300Z - 111200Z

...THERE IS A SLGT RISK OF SVR TSTMS PARTS OF SRN THROUGH SERN TX...

...SYNOPSIS...
A PROGRESSIVE SPLIT FLOW PATTERN WILL PREVAIL THIS PERIOD...WITH NRN
MEXICO UPR LOW CONTINUING E TO ENE INTO CNTRL TX AS LWR GRT LKS
TROUGH FURTHER AMPLIFIES UPON MOVING E INTO NEW ENGLAND AND THE MID
ATLANTIC. ELSEWHERE...POSITIVE-TILT PACIFIC NW/NRN RCKYS TROUGH
EXPECTED TO REACH THE NRN PLNS BY 12Z FRI.

AT THE SFC...FRONTAL ZONE THAT ENTERED THE LWR RIO GRANDE ON TUE
SHOULD STRENGTHEN AND REDEVELOP NWD INTO S TX LATER TODAY...WHILE
THE ERN PART OF THE SAME BOUNDARY CONTINUES SLOWLY SE ACROSS
CNTRL/SRN FL. THE BOUNDARY...AND ASSOCIATED WAA FIELD...WILL SERVE
AS A FOCUS FOR STRONG TO SVR TSTMS OVER PARTS OF TX TODAY THROUGH
EARLY FRI...AND ALSO MAY SUPPORT SCTD STRONG STORMS IN FL THIS AFTN.


...S CNTRL INTO S AND SE TX TODAY/TNGT...
COMBINATION OF VERY RICH MOISTURE /PW 1.25 TO 1.75 INCHES WITH UPR
60S TO LOW 70S F DEWPOINTS/...INCREASING WAA/UPR ASCENT WITH
APPROACHING UPR LOW...AND SFC HEATING EXPECTED TO SUPPORT SEVERAL
EPISODES OF STRONG TO SVR TSTMS OVER A LARGE PART OF SRN AND SERN TX
THIS PERIOD.

CURRENT BAND OF SCTD STORMS OVER THE LWR RIO GRANDE VLY LIKELY IS
BEING FOSTERED BY LOW LVL WAA/MOISTURE TRANSPORT ATOP AFOREMENTIONED
SFC FRONT. THE STORMS IN THE SRN PORTION OF THE BAND LIKELY WILL
BECOME MORE NEARLY SFC-BASED AS SFC HEATING DESTABILIZES REGION
LATER THIS MORNING. WITH AMPLE SHEAR ALREADY IN PLACE FOR
SUPERCELLS...SETUP MAY POSE A RISK FOR TORNADOES IN ADDITION TO
LARGE HAIL/LOCALLY DMGG WIND.

LATER TODAY ANOTHER ROUND OF SVR STORMS IS EXPECTED TO DEVELOP INVOF
THE FRONT AND IN EXIT REGION OF STRENGTHENED S/SSELY LLJ IN THE SRN
HILL COUNTRY AND/OR THE AREA NEAR DEL RIO. WITH DIURNAL
HEATING...STEEP MID LVL LAPSE RATES...AND CONTINUED LOW LVL MOISTURE
INFLOW...STRONG INSTABILITY WILL EXIST ACROSS REGION...WITH SBCAPE
ON THE ORDER OF 2000-2500 J/KG. COUPLED WITH 50+ KT WSWLY DEEP
SHEAR AND INCREASED FORCING FOR ASCENT E OF APPROACHING UPR
LOW...SETUP COULD YIELD A FAIRLY CONCENTRATED AREA OF STRONG TO SVR
SUSTAINED STORMS/SUPERCELLS. THESE COULD PRODUCE VERY LARGE
HAIL...DMGG WIND...AND TORNADOES. OTHER SVR STORMS MAY FORM ON THE
NRN MEXICAN MOUNTAINS AND MOVE E INTO S TX. ALL OF THIS ACTIVITY
COULD EVOLVE INTO A SIZABLE MCS...WITH EMBEDDED FORWARD-PROPAGATING
SEGMENTS EXTENDING A RISK FOR SVR WIND...HAIL...AND POSSIBLY ISOLD
TORNADOES TO THE TX CSTL PLN THIS EVE. PARTS OF S CNTRL TX TO THE
CNTRL TX GULF CST MAY REQUIRE UPGRADE TO MDT RISK AS THE MOST LIKELY
STORM MODE AND AREA OF AFTN STORM DEVELOPMENT BECOME MORE APPARENT.

ADDITIONAL STRONG TO SVR STORMS MAY AFFECT PARTS OF DEEP S TX AND
THE MIDDLE/UPR TX CSTL PLN THROUGH FRI AS LOW LVL MOISTURE CONTINUES
TO FLOW INTO REGION BENEATH FAVORABLE UPR DIFLUENCE.

...SERN FL THIS AFTN...
AFOREMENTIONED COLD FRONT AND SEA BREEZE BOUNDARIES MAY SUPPORT
ISOLD TO WIDELY SCTD TSTMS THIS AFTN...PRIOR TO ONSET OF MORE
STRONGLY SUBSIDENT MID-LVL THIS EVE. RELATIVELY STEEP LOW LVL LAPSE
RATES AND RICH MOISTURE /PW AOA 1.50 INCHES AND SFC DEWPOINTS NEAR
70 F/ MAY FOSTER LOCALLY STRONG/POSSIBLY SVR DOWNDRAFTS AND PERHAPS
HAIL GIVEN 25-30 KT WLY MID LVL FLOW.

...NRN PLNS LATE THIS AFTN/EVE...
LOW-LVL MOISTURE RETURN WILL BE QUITE LIMITED AHEAD OF COLD FRONT
THAT WILL CROSS THE DAKOTAS LATER TODAY/TNGT ATTENDANT TO NRN RCKYS
UPR TROUGH. SFC HEATING WILL NEVERTHELESS DESTABILIZE REGION NEAR
THE FRONT...AND LIKELY WILL CONTRIBUTE TO STORM DEVELOPMENT ALONG
OR...MORE LIKELY...IMMEDIATELY BEHIND THE FRONT LATE TODAY INTO
TNGT. A CONDITIONAL RISK FOR STRONG WIND GUSTS CANNOT BE RULED OUT
IF SFC-BASED STORMS DO INDEED DEVELOP...GIVEN STEEP PRE FRONTAL LOW
LVL LAPSE RATES AND MODERATE MEAN WIND FIELD.
ATTM...HOWEVER...CONFIDENCE IN SUCH A SCENARIO REMAINS TOO LOW TO
WARRANT INCLUSION OF SVR WIND PROBABILITIES.

..CORFIDI/GARNER.. 05/10/2012

[srainhoutx]

The frontal boundary is beginning to retreat slowly N across the Metro Area the morning.

PSX and points South still have Northeast winds, but dewpoints are approaching 70ºF. 64ºF at ARM. PSX I think may be just North of the true front. Not completely sure if that is the true front, but we can be North of the front if dewpoints are pushing 70ºF and still get surface based storms, I'd think.

Winds have just turned out of the ESE up here, Ed...

[unome]

http://hint.fm/wind/

not meant to be a weather tool, but it's awesome

edited to change "real-time" to "near-term", also to add the following from their website:

The wind map is a personal art project, not associated with any company. We've done our best to make this as accurate as possible, but can't make any guarantees about the correctness of the data or our software. Please do not use the map or its data to fly a plane, sail a boat, or fight wildfires

If the map is missing or seems slow, we recommend the latest Chrome browser.

Surface wind data comes from the National Digital Forecast Database. These are near-term forecasts, revised once per hour. So what you're seeing is a living portrait. (See the NDFD site for precise details; our timestamp shows time of download.) And for those of you chasing top wind speed, note that maximum speed may occur over lakes or just offshore.

We'd be interested in displaying data for other areas; if you know of a source of detailed live wind data for other regions, or the entire globe, please let us know.

If you're looking for a weather map, or just want more detail on the weather today, see these more traditional maps of temperature and wind.

HINT.FM.

[srainhoutx]

Update from Jeff:

Large slow moving upper level storm system to bring several rounds of heavy rainfall to Harris County.



Thunderstorms have already developed out west of the area this morning and are moving toward the county. Forecast models are in decent agreement on a round of storms late this afternoon followed by another round early Friday morning. A fairly dry air mass in place currently will rapidly moisten today with moisture levels increasing to nearly 200% of normal by late tonight. A large thunderstorm complex will develop over SC TX this afternoon and move across the region early Friday with a slowing forward motion.



Excessive hourly rainfall rates of 2-3 inches will be possible with this line of thunderstorms. While grounds are dry from the recent dry spell, very high moisture levels, potential slow storm motions, and the slow motion of the main upper level storm all point to a threat for an extended period of potential heavy rains from late this afternoon through Saturday midday. Small scale features that global forecast models cannot resolve will likely determine where the heaviest rains will fall…current thinking via model guidance and WGRFC forecasters in near or south of I-10. Widespread 1-3 inches is likely with isolated amounts of 3-5 inches possible.



Rainfall of this magnitude even on dry grounds will result in significant run-off especially over urban areas. Ponding and flooding of low lying areas and areas of poor drainage will be possible. NWS may issue a Flash Flood Watch later today based on radar and model trends.

[srainhoutx]

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1126 AM CDT THU MAY 10 2012

VALID 101630Z - 111200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF CNTRL AND SRN
TX...

...SYNOPSIS...

A PROGRESSIVE...SPLIT FLOW PATTERN WILL EXIST ACROSS THE CONUS THIS
PERIOD WITH THE PRIMARY FEATURE OF INTEREST BEING SUBTROPICAL BRANCH
UPPER LOW WHICH WILL TRANSLATE FROM NWRN MEXICO INTO CNTRL TX.
WITHIN THE POLAR BRANCH OF WESTERLIES...A TROUGH WILL AMPLIFY FROM
ERN CANADA THROUGH NEW ENGLAND TO THE MID-ATLANTIC
COAST...DOWNSTREAM FROM A MIGRATORY SHORTWAVE TROUGH MOVING THROUGH
THE CANADIAN PRAIRIE PROVINCES AND NRN PLAINS.

AT THE SURFACE...THE TENDENCY FOR BAROCLINIC ZONE LOCATED ACROSS
PORTIONS OF THE LOWER RIO GRANDE VALLEY AND S-CNTRL TX TO LIFT NWD
AHEAD OF UPPER LOW MAY BE OFFSET BY CONVECTIVE COLD POOL GENERATION
TO THE N...YIELDING LITTLE NET MOVEMENT TO FRONT. THE ERN EXTENSION
OF THIS BOUNDARY OVER THE CNTRL FL PENINSULA WILL...HOWEVER...
CONTINUE SWD THROUGH THE REMAINDER OF THE STATE. ELSEWHERE...A COLD
FRONT ASSOCIATED WITH THE N-CNTRL CONUS SHORTWAVE TROUGH WILL
ADVANCE ACROSS THE NRN PLAINS INTO UPPER MS VALLEY WITH SWRN PORTION
OF BOUNDARY MOVING SWD INTO THE CNTRL HIGH PLAINS.

...EDWARDS PLATEAU/CONCHO VALLEY EWD TO THE UPPER TX COAST AND SWD
INTO DEEP S TX TODAY AND TONIGHT...

12Z CRP/BRO/DRT SOUNDINGS SHOWED THE PRESENCE OF A VERY MOIST
ENVIRONMENT /I.E. PW VALUES OF 1.5-2.0 INCHES/ AND STEEP MIDLEVEL
LAPSE RATES WHICH ARE CONTRIBUTING TO MLCAPE VALUES OF 1500-2500
J/KG AS OF MID MORNING. INCREASED DIABATIC WARMING OF BOUNDARY
LAYER COUPLED WITH COOLING MIDLEVEL TEMPERATURES WILL SUPPORT
FURTHER DESTABILIZATION THROUGH PEAK OF THE DIURNAL HEATING CYCLE
WITH ENVIRONMENT BECOMING STRONGLY UNSTABLE AT LOCATIONS SOUTH OF
THE FRONT.

REGENERATIVE STRONG-SEVERE TSTM DEVELOPMENT IS ANTICIPATED THROUGH
MUCH OF THE D1 PERIOD AS FORCING FOR ASCENT ATTENDANT TO UPPER LOW
EDGES EWD AND INTERACTS WITH THE MOIST...MODERATE-STRONGLY UNSTABLE
ENVIRONMENT. MORE SPECIFICALLY...A NOTABLE INCREASE IN STORM
COVERAGE AND VIGOR IS ANTICIPATED LATER THIS AFTERNOON INTO EVENING
ACROSS PORTIONS OF THE EDWARDS PLATEAU INTO THE HILL COUNTRY IN
ASSOCIATION WITH A STRONG VORTICITY MAXIMUM ROTATING AROUND
PERIPHERY OF UPPER LOW.

THE EWD PROGRESSION OF MID AND HIGH-LEVEL JET STREAKS ACROSS THE
LOWER RIO GRANDE VALLEY WILL RESULT IN PRONOUNCED VERTICAL VEERING
OF WINDS WITH HEIGHT WITH EFFECTIVE BULK SHEAR STEADILY
STRENGTHENING TO 50-60 KT. AS SUCH...THE ENVIRONMENT WILL BECOME
INCREASINGLY SUPPORTIVE OF INTENSE SUPERCELLS CAPABLE OF VERY LARGE
HAIL...TORNADOES...AND DAMAGING WIND GUSTS. UPSCALE GROWTH INTO ONE
OR MORE FORWARD-PROPAGATING MCSS IS POSSIBLE TONIGHT WITH THE
POTENTIAL FOR CORRIDORS OF WIND DAMAGE.

...E-CNTRL/SERN FL PENINSULA THIS AFTERNOON...

LARGE-SCALE FORCING FOR ASCENT WILL REMAIN NEGLIGIBLE ACROSS THE
AREA...BUT THE PRESENCE OF DEEP WLY FLOW SHOULD ENHANCE CONVERGENCE
ALONG THE ERN SEA BREEZE THIS AFTERNOON. WHEN COUPLED WITH SWD
ADVANCEMENT OF COLD FRONT...EXPECT WIDELY SCATTERED-SCATTERED TSTM
DEVELOPMENT THIS AFTERNOON WITHIN A THERMODYNAMIC ENVIRONMENT
FEATURING MLCAPE OF 1000-2000 J/KG. THIS INSTABILITY WILL ALIGN
WITH AN EWD-DEVELOPING SUBTROPICAL UPPER JET STREAK WITH SETUP
SUPPORTIVE OF MULTICELL AND MARGINAL SUPERCELL STRUCTURES CAPABLE OF
LOCALLY DAMAGING WINDS...SOME HAIL...AND PERHAPS A BRIEF TORNADO.

...NRN PLAINS THIS AFTERNOON AND EVENING...

DESPITE THE PRESENCE OF A RELATIVELY DRY AIR MASS /PER 12Z REGIONAL
SOUNDINGS/...MODEL GUIDANCE INDICATE THAT STEEP MIDLEVEL LAPSE RATES
AND STRONG DAYTIME HEATING WILL YIELD A MODERATELY UNSTABLE
ENVIRONMENT BY AFTERNOON WITH MLCAPE APPROACHING 1000 J/KG. A
DEEPENING FRONTAL CIRCULATION WILL COMBINE WITH INCREASING HEIGHT
FALLS/FORCING FOR ASCENT DOWNSTREAM FROM POLAR BRANCH SHORTWAVE
TROUGH TO FOSTER ISOLATED TSTMS BY LATE AFTERNOON OR EARLY EVENING.
VERTICAL SHEAR WILL REMAIN MARGINALLY STRONG FOR STORM
ORGANIZATION/SUSTENANCE...BUT THE PRESENCE OF THE STEEP LAPSE RATES
AND DEEPLY MIXED BOUNDARY LAYER MAY PROMOTE LOCALLY STRONG WIND
GUSTS AND PERHAPS SOME HAIL.

..MEAD/BUNTING/LEITMAN.. 05/10/2012

[srainhoutx]

Code: Select all

BULLETIN - IMMEDIATE BROADCAST REQUESTED
     TORNADO WATCH OUTLINE UPDATE FOR WT 271
     NWS STORM PREDICTION CENTER NORMAN OK
     1140 AM CDT THU MAY 10 2012
     
     TORNADO WATCH 271 IS IN EFFECT UNTIL 800 PM CDT FOR THE
      FOLLOWING LOCATIONS
     
     TXC007-013-025-047-057-061-123-127-131-163-175-215-247-249-255-
     261-273-283-297-311-323-355-391-409-427-469-479-489-493-505-507-
     110100-
     /O.NEW.KWNS.TO.A.0271.120510T1640Z-120511T0100Z/
     
     TX 
     .    TEXAS COUNTIES INCLUDED ARE
     
     ARANSAS              ATASCOSA            BEE                 
     BROOKS               CALHOUN             CAMERON             
     DEWITT               DIMMIT              DUVAL               
     FRIO                 GOLIAD              HIDALGO             
     JIM HOGG             JIM WELLS           KARNES              
     KENEDY               KLEBERG             LA SALLE            
     LIVE OAK             MAVERICK            MCMULLEN            
     NUECES               REFUGIO             SAN PATRICIO        
     STARR                VICTORIA            WEBB                
     WILLACY              WILSON              ZAPATA              
     ZAVALA               
     
     
     GMZ130-132-135-150-155-230-235-250-255-110100-
     /O.NEW.KWNS.TO.A.0271.120510T1640Z-120511T0100Z/
     
     CW 
     
     .    ADJACENT COASTAL WATERS INCLUDED ARE
     
     LAGUNA MADRE FROM THE PORT OF BROWNSVILLE TO THE ARROYO COLORADO 
     
     LAGUNA MADRE FROM THE ARROYO COLOARDO TO 5 NM NORTH OF PORT
     MANSFIELD TX 
     
     LAGUNA MADRE FROM 5 NM NORTH OF PORT MANSFIELD TO BAFFIN BAY TX 
     
     COASTAL WATERS FROM PORT MANSFIELD TX TO THE RIO GRANDE RIVER OUT
     20 NM 
     
     COASTAL WATERS FROM BAFFIN BAY TO PORT MANSFIELD TX OUT 20 NM 
     
     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 
     
     ATTN...WFO...CRP...BRO...EWX...

[srainhoutx]

MESOSCALE DISCUSSION 0774
NWS STORM PREDICTION CENTER NORMAN OK
1152 AM CDT THU MAY 10 2012

AREAS AFFECTED...MIDDLE RIO GRANDE VALLEY INTO PARTS OF CENTRAL TX

CONCERNING...SEVERE THUNDERSTORM WATCH 270...

VALID 101652Z - 101745Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 270
CONTINUES.

SUMMARY...SEVERE THREAT CONTINUES FROM THE MIDDLE RIO GRANDE VALLEY
EWD INTO PARTS OF CENTRAL TX. NEW WW WILL LIKELY BE NEEDED AS
REMAINING PORTIONS OF WW 270 ARE SET TO EXPIRE AT 10/18Z.

DISCUSSION...THE EWD-MOVING UPPER LOW CONTINUES TO APPROACH FAR W TX
PER THE LATEST WV SATELLITE LOOP...WITH STORMS ONGOING ACROSS PARTS
OF CENTRAL AND S TX AHEAD OF THIS FEATURE. WHILE THE MOST FAVORABLE
THERMODYNAMIC ENVIRONMENT EXISTS ACROSS S TX -- WHERE NEWLY ISSUED
TORNADO WATCH 271 RESIDES...THE ENVIRONMENT FARTHER N ACROSS THE
REMAINING PORTION OF WW 270 REMAINS SUGGESTIVE OF DAMAGING WIND/HAIL
POTENTIAL. WITH THE BACKGROUND ENVIRONMENT SUPPORTING PERSISTENT
CONVECTIVE ACTIVITY...CONTINUATION OF THE ONGOING SEVERE POTENTIAL
WARRANTS NEW WW ISSUANCE ACROSS THIS REGION.

..GOSS/MEAD.. 05/10/2012


ATTN...WFO...FWD...EWX...SJT...MAF...

[Ptarmigan]

I wouldn't be surprised if there is flooding from this rain event. Some areas may see up to 10 inches of rain once it is all over.

[srainhoutx]

A lot of rotating super cells now in S/S Central Texas. A Moderate Risk may have been warranted...

[srainhoutx]

Code: Select all

SEVERE THUNDERSTORM WATCH OUTLINE UPDATE FOR WS 272
NWS STORM PREDICTION CENTER NORMAN OK
1235 PM CDT THU MAY 10 2012

SEVERE THUNDERSTORM WATCH 272 IS IN EFFECT UNTIL 800 PM CDT
FOR THE FOLLOWING LOCATIONS

TXC019-021-029-031-053-055-091-095-137-149-171-177-187-209-259-
265-267-271-285-287-299-307-319-325-327-385-411-453-463-465-491-
110100-
/O.NEW.KWNS.SV.A.0272.120510T1735Z-120511T0100Z/

TX
.    TEXAS COUNTIES INCLUDED ARE

BANDERA              BASTROP             BEXAR
BLANCO               BURNET              CALDWELL
COMAL                CONCHO              EDWARDS
FAYETTE              GILLESPIE           GONZALES
GUADALUPE            HAYS                KENDALL
KERR                 KIMBLE              KINNEY
LAVACA               LEE                 LLANO
MASON                MCCULLOCH           MEDINA
MENARD               REAL                SAN SABA
TRAVIS               UVALDE              VAL VERDE
WILLIAMSON

[Ptarmigan]

There could be training. Severe flooding has happened in May.
http://www.wxresearch.com/almanac/houflood.html

[srainhoutx]

Update from Jeff:

Tornado Watch has been issued until 800pm for all of S TX and the coastal bend.



Discussion:

Strong lift with impressive upper level storm over NE MX this morning is overspreading S TX and the Rio Grande plains currently. Recent storms south of San Antonio and WSW of Corpus have grown into tornado producing supercells as the air mass has destabilized due to surface heating and influx of rich Gulf moisture. Strong jet streak on the southern flank of the upper system over NE MX is translating eastward into SC/S TX currently with increasing shearing being produced as surface winds remain backed to the south and near the returning frontal boundary. Additional heating and stronger forcing arriving in the next few hours will continue to support supercell formation with tornadoes, very large hail and wind damage all threats.



Good potential for supercells to congeal into a large MCS late this afternoon and approach the region overnight. Potential appears to be increasing for widespread corridors of wind damage overnight as this storm complex moves to the TX coastal plain. As suspected this morning, SPC has pushed the slight risk region to include the SW ½ of SE TX for tonight and some additional expansion to the NE may be required.



Main threats this afternoon will be supercells with very large hail and possible tornadoes mainly WSW and SW of our area and then the threat will transition into a damaging wind threat overnight as the complex moves into and across SE TX. Damaging winds on the leading edge of the complex are possible as strong mid level energy is brought to the surface and possible meso low formation bow out the leading edge of the line are various locations and times. Isolated short lived tornadoes will also be possible along the leading edge of the line especially near any couplet segments. Additional weather watches are likely into the overnight hours.

[rnmm]

Before it gets too crazy around here, I just want to say Thank You to all for keeping us updated! I really do appreciate the time and effort you all take to make sure we stay up to date and safe!! You guys rock!!!

[Katdaddy]

I agree with you Ed. Feel we will have a tornado threat S of I-10 later today. Supercells S and E of San Antonio are headed our way. Would not be surprised to see a Tornado Watch posted for the southern part of SE TX in the upcoming hours.

[txflagwaver]

Looks like it's moving more North than East

[rnmm]

Looks like it's moving more North than East

Wouldn't that put the more severe storms well away from our area?