May: Isolated Showers To End The Month

Tue May 21, 2013 10:45 am

http://forecast.weather.gov/product.php ... glossary=1

000
FXUS64 KHGX 211524
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1024 AM CDT TUE MAY 21 2013

.DISCUSSION...
THE MAIN PROBLEM OF THE DAY CONTINUES TO BE THE TIMING AND
POSSIBILITY OF THUNDERSTORMS...MAINLY OVER THE NORTHERN COUNTIES
THIS AFTERNOON AND EVENING. THERE WAS A SPECIAL SOUNDING CONDUCTED
BY TEXAS A&M WHICH STILL SHOWED A CAP AT AROUND 900 MB. THE HIGH
RES MODEL ARW AND NMM DIFFERED A BIT ON THE TIMING...BUT BOTH
INDICATE THAT THE STORMS SHOULD BEGIN TO AFFECT LOCATIONS ALONG
AND NORTH OF A LINE FROM COLLEGE STATION TO CROCKETT DURING THE
EARLY AND MID EVENING. WILL TRY AND TIME THE EVENTS AFTER THE 12Z
MODELS COME IN. FOR NOW THE CURRENT FORECAST FOR TODAY IS ON TRACK
AND AN UPDATE IS NOT ANTICIPATED.

40

&&

Tue May 21, 2013 11:35 am

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1128 AM CDT TUE MAY 21 2013

VALID 211630Z - 221200Z

...THERE IS A MDT RISK OF SVR TSTMS FOR N-CNTRL/NERN TX...SRN
AR...NWRN LA...FAR SERN OK...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN PLAINS TO THE
TN/OH VALLEYS AND THE LOWER GREAT LAKES/NORTHEAST...

...SUBSTANTIAL SEVERE WEATHER EXPECTED ACROSS N-CNTRL TX TO THE
ARKLATEX THIS AFTERNOON AND EVENING...

..SRN PLAINS TO LOWER MS VALLEY...
SIGNIFICANT SEVERE WEATHER EPISODE INITIALLY UNFOLDING ACROSS THE
RED RIVER WITH SUPERCELLS PRODUCING LARGE HAIL ALONG AND N OF THE
COMPOSITE OUTFLOW/COLD FRONT PUSHING SWD FROM THE BIG COUNTRY TO FAR
SERN OK AHEAD OF A WELL-DEFINED SHORTWAVE TROUGH OVER THE SRN HIGH
PLAINS. AIR MASS S OF THE BOUNDARY IS BECOMING STRONGLY UNSTABLE AS
GRADUAL SURFACE HEATING CONTINUES AMIDST LOWEST 100 MB MEAN MIXING
RATIOS OF 14-17 G/KG AND 700-500 MB LAPSE RATES OF 8 TO 9.5 DEG C/KM
SAMPLED IN ALL REGIONAL 12Z RAOBS. AS MLCIN IS MINIMIZED ALONG THE
DRYLINE MIXING EWD ACROSS THE EDWARDS PLATEAU...ADDITIONAL SUPERCELL
DEVELOPMENT IS ANTICIPATED WITH SWD EXTENT.

A BELT OF 50-60 KT MID-LEVEL SWLYS ATTENDANT TO THE COMPACT
SHORTWAVE TROUGH WILL PROMOTE RISKS FOR ALL SEVERE TYPES /SOME OF
WHICH WILL BE SIGNIFICANT/. MORNING CONVECTION-ALLOWING WRF AND HRRR
SIMULATIONS ARE INSISTENT THAT UPSCALE GROWTH WILL OCCUR THROUGHOUT
THE AFTERNOON. GIVEN THE DEGREE OF INSTABILITY...BUOYANCY AND
SHEAR...SETUP MAY YIELD A DERECHO ACCELERATING EWD TOWARDS THE
ARKLATEX REGION BY EARLY EVENING. HERE TOO...THE STRONGEST LOW-LEVEL
S/SWLYS WILL REMAIN...PROMOTING EMBEDDED MESOVORTICES CAPABLE OF
PRODUCING A COUPLE OF SIGNIFICANT TORNADOES. OTHERWISE...POTENTIAL
DOES EXIST FOR WIDESPREAD/DESTRUCTIVE DAMAGING WIND GUSTS.

...TN VALLEY TO THE LOWER GREAT LAKES/NORTHEAST...
A BROAD AREA OF ORGANIZED SEVERE POTENTIAL IS EXPECTED ALONG THE ERN
EXTENT OF THE ELEVATED MIXED LAYER PLUME SAMPLED IN 12Z RAOBS. WITH
ROBUST HEATING...MODERATE TO STRONG INSTABILITY IS ANTICIPATED...BUT
MOST OF THE REGION WILL REMAIN ON THE FRINGE OF SUFFICIENT
DEEP-LAYER SHEAR FOR SUPERCELLS. THREE ZONES OF FOCUS FOR SUSTAINED
CONVECTION ARE APPARENT. ONE WILL BE DOWNSTREAM OF AN ONGOING
CLUSTER ACROSS WRN TN. THE OTHERS SHOULD BE ALONG A QUASI-STATIONARY
FRONT BISECTING NY INTO SRN NEW ENGLAND AND PERHAPS IN ASSOCIATION
WITH A WEAK MCV MOVING INTO LOWER MI. MULTICELL CLUSTERS AND A FEW
SUPERCELLS WILL BE PRIMARILY CAPABLE OF ISOLATED DAMAGING WINDS AND
SEVERE HAIL.

..GRAMS/ROGERS.. 05/21/2013

Tue May 21, 2013 11:41 am

a nice comparison of TCEQ's latest image of Texas & NMQ's echo top feature

http://www.tceq.texas.gov/assets/public ... atest.jpeg

http://nmq.ou.edu/

Tue May 21, 2013 11:45 am

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
1142 AM CDT TUE MAY 21 2013

TXZ171>173-183>194-202>209-217>225-228-211845-
LLANO-BURNET-WILLIAMSON-VAL VERDE-EDWARDS-REAL-KERR-BANDERA-
GILLESPIE-KENDALL-BLANCO-HAYS-TRAVIS-BASTROP-LEE-KINNEY-UVALDE-
MEDINA-BEXAR-COMAL-GUADALUPE-CALDWELL-FAYETTE-MAVERICK-ZAVALA-
FRIO-ATASCOSA-WILSON-KARNES-GONZALES-DE WITT-LAVACA-DIMMIT-
INCLUDING THE CITIES OF...LLANO...BURNET...GEORGETOWN...DEL RIO...
ROCKSPRINGS...LEAKEY...KERRVILLE...BANDERA...FREDERICKSBURG...
BOERNE...BLANCO...SAN MARCOS...AUSTIN...BASTROP...GIDDINGS...
BRACKETTVILLE...UVALDE...HONDO...SAN ANTONIO...NEW BRAUNFELS...
SEGUIN...LOCKHART...LA GRANGE...EAGLE PASS...CRYSTAL CITY...
PEARSALL...PLEASANTON...FLORESVILLE...KARNES CITY...GONZALES...
CUERO...HALLETTSVILLE...CARRIZO SPRINGS
1142 AM CDT TUE MAY 21 2013

...EXTREMELY UNSTABLE AIRMASS POISED TO ERUPT IN SEVERE THUNDERSTORMS
WITH LARGE HAIL AND DAMAGING WINDS BY LATE AFTERNOON THROUGH THIS
EVENING...

RICH LOW LEVEL GULF MOISTURE COUPLED WITH DAYTIME HEATING AND
COLD AIR ALOFT WILL RESULT IN AN EXTREMELY UNSTABLE AIR MASS
ACROSS SOUTH CENTRAL TEXAS FROM LATE THIS MORNING THROUGH EARLY
EVENING. THUNDERSTORM DEVELOPMENT IS EXPECTED BEGINNING BY EARLY
THIS AFTERNOON AS AN AN UPPER LEVEL TROUGH AND COLD FRONT APPROACH
FROM THE WEST. SCATTERED THUNDERSTORMS WILL DEVELOP RAPIDLY BY
LATE AFTERNOON...QUICKLY BECOMING SEVERE AS THE FRONT ENCOUNTERS
THIS UNSTABLE AIR MASS. THE MAIN THREATS WILL BE FROM LARGE HAIL
AND DAMAGING THUNDERSTORM WINDS...HOWEVER WITH THE EXTREME
INSTABILITY PRESENT...ISOLATED TORNADOES CANNOT BE RULED OUT. MUCH
OF THE EASTERN HALF OF SOUTH CENTRAL TEXAS...MAINLY EAST OF A
KERRVILLE TO CARRIZO SPRINGS LINE...WILL BE AFFECTED FROM LATE
AFTERNOON UNTIL THE EARLY MORNING HOURS WEDNESDAY. IN
ADDITION...RAINFALL AMOUNTS MAY AVERAGE 1 TO 3 INCHES WITHIN THE
HEAVIEST STORMS PRODUCING SOME LOCALIZED FLOODING.

HEIGHTENED CONCERN EXISTS ALONG AND NORTH OF A BURNET TO AUSTIN TO
GIDDINGS LINE THIS EVENING...WHERE THE MOST UNSTABLE CONDITIONS WILL
RESIDE. THIS AREA WILL BE MOST AT RISK FOR VERY LARGE HAIL AND
ISOLATED TORNADOES.

THE WEATHER SYSTEM SHOULD EXIT THE REGION BY EARLY WEDNESDAY
MORNING...WITH HEAVY RAINS AND SEVERE WEATHER CONCERNS MOVING EAST
OF THE REGION.

Tue May 21, 2013 12:31 pm

Update from Jeff:

SPC has issued a large tornado watch for much of N and portions of C TX until 700pm.

Outflow boundary from S OK convection is surging southward over N TX while at the same time the dry line/cold front combo is approaching from the west. The air mass over N and C TX is becoming very unstable with CAPE values of 3000-4000 J/kg along the I-35 corridor. With continued surface heating, expect supercells to develop within the next few hours from NW of Fort Worth SSW along the dry line deep into C TX. Backed low level winds near the incoming outflow boundary from the NW may help to enhance the tornado threat near/around Fort Worth over the next several hours.

Southern flank supercells that fire along the dry line west of Austin/Waco will have a high end tornado threat along with a very large hail threat (greater than 2.0 inches in diameter). Storms will congeal into a forward fast moving line by this evening with a very significant wind damage threat (frequent speeds to hurricane force) spreading across much of NTX into our northern counties. Short term high resolution models continue to suggest a bow echo evolving over N TX with southern flank supercells with a tornado threat across central TX. Think the biggest tornado threat will reside NW of a line from Austin to near College Station to Lufkin and ahead of the main squall line.

Meso models continue to trend toward bring an MCS/bow echo into and possibly even through much of SE TX overnight. Still some questions on the cap intensity with the same models showing a building cap after sunset from deep south TX into the coastal bend so even though the meso models are wanting to bring storms all the way to the coast, the thermodynamic profile may not be very favorable south of I-10.

Tue May 21, 2013 1:12 pm

Can anyone get me a GGG sounding (Longview).

Tue May 21, 2013 1:23 pm

Thank you Ed!

Tue May 21, 2013 1:28 pm

MESOSCALE DISCUSSION 0752
NWS STORM PREDICTION CENTER NORMAN OK
0119 PM CDT TUE MAY 21 2013

AREAS AFFECTED...NRN TX INTO THE ARKLATEX REGION

CONCERNING...TORNADO WATCH 201...

VALID 211819Z - 212015Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 201 CONTINUES.

SUMMARY...STORMS ARE GRADUALLY INCREASING IN COVERAGE...AND MAY
RAPIDLY INTENSIFY CLOSE TO OR JUST E OF THE DALLAS/FT. WORTH AREA
EWD INTO THE ARKLATEX WITH MAINLY DAMAGING WINDS AND HAIL.

DISCUSSION...SURFACE ANALYSIS AND VISIBLE IMAGERY SHOW THAT A BAND
OF THICK STRATUS CONTINUES TO HAMPER HEATING AND SURFACE BASED
DESTABILIZATION W OF THE I-35 CORRIDOR IN TX AS OUTFLOW AND COLD
FRONT CONTINUE TO RAPIDLY TRAVEL SEWD OVER WRN N TX.
CURRENTLY...THESE STORMS ARE FORMING MAINLY BEHIND THE LEADING
OUTFLOW...DUE IN PART TO THE COOLER SURFACE AIR AND MARGINAL STORM
RELATIVE INFLOW.

HOWEVER...HEATING PERSISTS ALONG AND E OF I-35...WITH TEMPERATURES
MAINLY IN THE 82-84 F RANGE. MODIFICATION OF THE 18Z FWD SOUNDING
SUGGESTS CAPPING IN THESE AREAS IS AT A MINIMUM...AND THAT THE
APPROACHING LINE OF CONVECTION WILL STRENGTHEN AS IT BEGINS TO
INGEST MORE UNSTABLE AIR. A GENERAL SWWD GROWTH ALONG THE COLD FRONT
IS ALSO EXPECTED LATER THIS AFTERNOON TOWARD THE WACO AREA. GIVEN
THE RAPIDLY ADVANCING GUST FRONT...AND VEERED 850 MB WINDS PRIMARILY
PARALLEL TO THE BOUNDARY...THE TORNADO THREAT MAY NOT BE HIGH...BUT
IF SUPERCELLS CAN FORM THEN ROTATION COULD DEVELOP ALONG ANY
INFLECTION POINTS IN THE LINE.

ELSEWHERE...AN OUTFLOW BOUNDARY CONTINUES TO SAG SWD ACROSS THE RED
RIVER INTO NRN TX AND SWRN AR...WITH SPORADIC SMALL STORMS FORMING
TO THE N OF IT. THESE CELLS MAY BECOME A BIT BETTER ORGANIZED AS THE
UPPER TROUGH NEARS...AND SOME FURTHER DESTABILIZATION OCCURS
UPSTREAM. DEEP LAYER SHEAR WILL REMAIN FAVORABLE FOR ELEVATED SEVERE
HAIL WITH THIS ACTIVITY PRIOR TO THE MAIN LINE OF STORMS ARRIVING
ACROSS THE RED RIVER VALLEY AND SWRN AR. ALSO...THERE IS A
CONDITIONAL TORNADO THREAT IF CELLS CAN MATURE BEFORE THEY CROSS THE
OUTFLOW BOUNDARY. HOWEVER...CELL MOTION WOULD CAUSE THESE STORMS TO
LOSE TORNADO THREAT QUICKLY ONCE THEY CROSS THE FRONT.

..JEWELL.. 05/21/2013

ATTN...WFO...SHV...TSA...FWD...OUN...EWX...SJT...

Tue May 21, 2013 1:28 pm

Ed Mahmoud wrote:1) Anyone had the 7 am Aggie sounding as an image (SPC sounding web page never shows it) and 2) a 17Z or 18Z sounding from the Aggies would be rather helpful, as again, they're look most likely of about anyplace in the HGX CWA to get severe action.

I'm guessing FWD and SHV will release balloons, but that doesn't help much down here.

I don't have an image but they were reporting 3000+ mucape, EHI of 3.6 and LI of -10 but shear was low and BKN was in the mid 50's indicating more of a multicell threat than discrete cells.

Tue May 21, 2013 2:08 pm

05212013 ww0205_overview_wou.gif

Tue May 21, 2013 2:56 pm

NWS Norman @NWSNorman
At least one area of EF-5 damage was found by survey crews. Details to follow later.

Tue May 21, 2013 3:30 pm

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE NORMAN OK
250 PM CDT TUE MAY 21 2013

...NWS DAMAGE SURVEY FOR 5/20/2013 NEWCASTLE/MOORE TORNADO EVENT -
UPDATE 3...

...NWS DAMAGE SURVEY HAS NOW RATED THE NEWCASTLE/MOORE TORNADO AS EF5...

.OVERVIEW...

THE NATIONAL WEATHER SERVICE DISPATCHED FOUR DAMAGE SURVEY TEAMS TO
THE PATH OF THE NEWCASTLE/MOORE OK TORNADO. NEW STATEMENTS WILL BE
ISSUED THROUGHOUT THE DAY AS THESE TEAMS REPORT FINDINGS. THIS
INFORMATION REMAINS PRELIMINARY AND THE INFORMATION HERE COULD
CHANGE.

.NEWCASTLE/MOORE TORNADO

RATING: EF5
ESTIMATED PEAK WIND: 200-210 MPH
PATH LENGTH /STATUTE/: 17 MILES
PATH WIDTH /MAXIMUM/: 1.3 MILES
FATALITIES: N/A
INJURIES: N/A

START DATE: MAY 20 2013
START TIME: 2:45 PM CDT
START LOCATION: 4.4 W NEWCASTLE /GRADY COUNTY /OK
START LAT/LON: 35.2580 / -97.6775

END DATE: MAY 20 2013
END TIME: 3:35 PM CDT
END LOCATION: 4.8 E OF MOORE OK /CLEVELAND COUNTY /OK
END LAT/LON: 35.3409 / -97.4007

SURVEY SUMMARY: EXPERTS SURVEYING IN MOORE HAVE DETERMINED DAMAGE IS
EF5 WITH MAXIMUM WINDS OVER 200 MPH. FOUR SURVEY TEAMS CONTINUE TO
INSPECT DAMAGE FROM THIS LONG TRACK TORNADO. INITIAL DAMAGE WAS
FOUND AROUND 4.4 MILES WEST OF NEWCASTLE...SOUTH OF TECUMSEH ROAD
ALSO KNOWN AS NW 16TH STREET AND EAST LAKE ROAD. THE TORNADO TRACKED
NE TO THE INTERSTATE 44 BRIDGE OVER THE CANADIAN RIVER AND THEN TOOK
A MORE EASTWARD TRACK THROUGH MOORE. TORNADO DAMAGE ABRUPTLY ENDS
0.3 MILES EAST OF AIR DEPOT ROAD AND N OF SE 134TH ST.

INITIALLY PRODUCING EF0 AND EF1 DAMAGE THE STORM INTENSIFIED VERY
RAPIDLY IN 4 MILES OR AROUND 10 MINUTES PRODUCING EF4 DAMAGE BEFORE
REACHING INTERSTATE 44. NUMEROUS INDICATIONS OF EF4 DAMAGE WITH SOME
AREAS NOW DETERMINED AT EF5 DAMAGE...THE HIGHEST CATEGORY ON THE EF
SCALE...WITH OVER 200 MPH WINDS.

ADDITIONAL INFORMATION SUCH AS MAXIMUM PATH WIDTH WILL BE UPDATED
AS THE TEAMS COMPLETE THEIR SURVEYS.

Tue May 21, 2013 3:37 pm

Update from Jeff Re Moore/Newcastle Tornado:

The attached PDF shows the Tornado Warning Operations yesterday at NWS Norman.

The twitter feed from their office shows the rapid ramp up in the severity of the situation between 230pm and 300pm.

Radar loop:

http://www.srh.noaa.gov/oun/?n=events-20130520-radar

Survey:

EF 5 damage found in the Moore portion of the damage track. Initial NWS ground survey indicates the tornado was on the ground for 17 miles (starting 4.4 miles west of Newcastle, OK at 245pm and ending 4.8 miles east of Moore, OK at 335pm. The tornado appears to have been an EF0/EF 1 and then rapidly grew and intensified as it moved across I-44 with damage greatly increasing to EF 4. The tornado remained an EF 4 through nearly all of Moore, OK. Damage survey teams are still working on the Moore section of the damage path, but indicate EF 5 damage has been found. The tornado will be rated an EF 5 maximum rating in the City of Moore. Preliminary radar sampling of storm chaser equipment suggest wind speeds may have approached 270mph in portions of Moore. Ground surveys are ongoing and this information is subject to change.

You Tube Tornado Video:

http://www.facebook.com/video/embed?vid ... 7107263068

http://www.wmctv.com/category/240217/vi ... start=true

http://www.facebook.com/video/embed?vid ... 4097727626

National Weather Service Norman Twitter feed:

* 12:08 p.m. -- @NWSNorman : Just launched a weather balloon. Cap is still there, but not strong and very breakable. Strong shear in place. #okwx

* 12:30 p.m. -- @NWSNorman: A tornado watch will be issued soon for much of Oklahoma. Stay alert! #okwx

* 12:51 p.m. -- @NWSNorman: 12:50pm - first signs on storm development on radar southeast of Lawton. #okwx

* 1:20 p.m. -- @NWSNorman: Tornado watch: rapid intense storm development expected next few hours, both near stalled front west of I-35, and near the dry line SW OK.

* 1:23 p.m. -- @NWSNorman: Isolated supercells likely along dry line with storms initially capable of very large hail. Tornado threat increases thru afternoon.

* 1:34 p.m. -- @NWSNorman: 1:33pm - rapidly intensifying storm near Pumpkin Center - NW Stephens Co - already producing nickel sized hail. #okwx

* 1:58 p.m. - @NWSNorman: 1:56pm - dry line visible on radar from SW of Minco to Elgin to Walters. Cold front from Minco to Yukon to Perkins. Areas S and E stay alert.

* 2:09 p.m. -- @NWSNorman: 2:08pm storms developing near Blanchard and Tuttle, moving NE at 30 mph. Stay alert Norman, Moore, and S OKC. Not severe yet. #okwx

* 2:13 p.m. -- @NWSNorman: 2:11pm - severe thunderstorm warning for OKC metro area. Severe storm near Bridge Creek moving NE 40 mph.#okwx

* 2:24 p.m. -- @NWSNorman: 2:22pm - things are getting very busy! Every storm that forms goes severe quickly. Please stay alert and be ready to act quickly! #okwx

* 2:30 p.m. -- @NWSNorman: 2:30pm - people in south OKC, Moore and north Norman need to be pay VERY close attention to the storm near Newcastle!! #okwx

* 2:34 p.m. -- @NWSNorman: One warning forecaster focusing on big supercell west of OKC. #okwx pic.twitter.com/MVbwWhvigl

* 2:39 p.m. -- @NWSNorman: 2:39pm - storm west of Newcastle is intensifying and showing some rotation. Stay alert! No tornado warning yet. #okwx

* 2:41 p.m. -- @NWSNorman: 2:40pm - TORNADO WARNING for OKC metro! Developing tornado near Newcastle moving E 20 MPH. Take shelter!! #okwx

* 2:46 p.m. -- @NWSNorman: 2:45pm - you DO NOT want to be in your car in a tornado! Stay where you are. Get in, get down and cover up. Tornado may affect Moore/S OKC

* 2:52 p.m. -- @NWSNorman: DO NOT take cover under highway overpasses!!! You will prevent people from getting to shelter. Get OFF THE ROAD and find a store, restaurant

* 2:56 p.m. -- @NWSNorman: 2:55pm - TORNADO! ON the north side of Newcastle moving east! #okwx

* 2:57 p.m. -- ‏@NWSNorman: Tornado north side of Newcastle at 2:56pm! pic.twitter.com/yryCp4WUW1

* 3:00 p.m. -- @NWSNorman: Large dangerous tornado at 3pm!!! pic.twitter.com/2hUzM0BV7k

* 3:01 p.m. -- @NWSNorman: 3:01pm - TORNADO EMERGENCY OKC METRO!!

* 3:03 p.m. -- @NWSNorman: 3:02pm - LARGE VIOLENT TORNADO moving toward Moore and SW OKC. Take cover right NOW!!! Do not wait!! #okwx

* 3:14 p.m. -- @NWSNorman: Large deadly tornado moving into Moore near 134th and Western. pic.twitter.com/YA2pzEegqG

* 3:19 p.m. -- @NWSNorman: 3:19pm - TORNADO Approaching area near Warren Theater in Moore! Please take shelter. This is as bad as it gets. #okwx

3:21 p.m. -- @NWSNorman: TORNADO EMERGENCY for the City of Moore. Get as far inside a sturdy building as you can. Cover up! Do not wait! #okwx

* 3:22 p.m. -- @NWSNorman: 3:22pm - the tornado is so large you may not realize it's a tornado. If you are in Moore, go to shelter NOW! #okwx

* 3:26 p.m. -- @NWSNorman: 3:25pm - tornado crossed I-35 in south Moore and is now moving along and south of 4th street. Take cover! #okwx

* 3:29 p.m. -- @NWSNorman: TORNADO EMERGENCY for Moore. 3:28pm pic.twitter.com/OiS2qIUcmc

* 3:34 p.m. -- @NWSNorman: 3:32pm - SE OKC is in immediate danger! Take cover. Large violent tornado moving your way. Do not wait to see the tornado! #okwx

* 3:35 p.m. -- @NWSNorman: 3:34pm - tornado moving toward lake Stanley Draper and will come VERY close to the KTLX radar site. #okwx

* 3:37 p.m. -- @NWSNorman: 3:36pm - tornado has roped out west of Lake Stanley Draper. #okwx

* ‏3:42 p.m. -- @NWSNorman: 3:40pm - Tornado could develop again at any time near Lake Stanley Draper! We are NOT in the clear yet! Stay alert! #okwx

Tue May 21, 2013 3:50 pm

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
345 PM CDT TUE MAY 21 2013

THE NATIONAL WEATHER SERVICE IN AUSTIN SAN ANTONIO HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
NORTHEASTERN BURNET COUNTY...
EXTREME NORTHWESTERN WILLIAMSON COUNTY...

* UNTIL 430 PM CDT.

* AT 343 PM CDT...NWS METEOROLOGISTS HAVE DETECTED A SEVERE
THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND DAMAGING
WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED NEAR WATSON...OR
13 MILES NORTH OF BERTRAM...AND MOVING NORTHEAST AT 40 MPH.

* SOME LOCATIONS IN THE WARNING INCLUDE BRIGGS.

Tue May 21, 2013 4:28 pm

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE FORT WORTH TX
423 PM CDT TUE MAY 21 2013

THE NATIONAL WEATHER SERVICE IN FORT WORTH HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
MCLENNAN COUNTY IN NORTH CENTRAL TEXAS...

* UNTIL 530 PM CDT

* AT 423 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND
DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED 6 MILES
NORTHEAST OF CRAWFORD...MOVING EAST AT 35 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
WOODWAY AROUND 430 PM...
WACO AND BEVERLY HILLS AROUND 440 PM...
LACY-LAKEVIEW AROUND 445 PM...
NORTHCREST AND BELLMEAD AROUND 450 PM...
WEST AROUND 455 PM...
HALLSBURG AROUND 500 PM...

THIS WILL IMPACT I-35 BETWEEN MILE MARKERS 337 AND 353.

Tue May 21, 2013 5:19 pm

MESOSCALE DISCUSSION 0758
NWS STORM PREDICTION CENTER NORMAN OK
0455 PM CDT TUE MAY 21 2013

AREAS AFFECTED...PARTS OF E-CNTRL AND SERN TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 212155Z - 212330Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...A STRONG TO SEVERE STORM THREAT WILL PROBABLY MOVE INTO
PORTIONS OF E-CNTRL AND SERN TX THIS EVENING/TONIGHT. ALTHOUGH
ISOLD LARGE HAIL/DMGG WINDS WILL BE THE PRIMARY THREATS...A TORNADO
IS ALSO POSSIBLE.

DISCUSSION...RADAR MOSAIC SHOWS AN EXTENSIVE SQUALL LINE FROM WRN AR
SWWD INTO N-CNTRL TX WITH SOME CELLULAR STORMS /INCLUDING THE BELL
COUNTY SUPERCELL/ ON THE SRN FRINGE OF THE LINE OF STORMS.
SUBJECTIVE SURFACE MESOANALYSIS SHOWS THE N-CNTRL TX PORTION OF THE
LINE JUXTAPOSED WITH THE COLD FRONT AND THEN EXTENDING SWWD OVER THE
TX HILL COUNTRY. FARTHER E...A PRE-FRONTAL CONFLUENCE ZONE HAS
SERVED TO PREFERENTIALLY FAVOR CELLULAR DEVELOPMENT ON THE SRN
PORTION OF THE LINE WITH THE FRONTAL LIFT DISPLACED 1-2 COUNTIES
WEST. SURFACE TEMPS HAVE WARMED TO NEAR 90 DEG F WITH DEWPOINTS
AROUND 70 DEG F...CONTRIBUTING TO A VERY UNSTABLE AIRMASS /2500-3000
MLCAPE PER OBJECTIVE ANALYSIS/. THE KGRK VWP SHOWS 0-6 KM SHEAR /40
KT/ MORE THAN SUFFICIENT FOR ORGANIZED LINE SEGMENTS AND SUPERCELLS.
ALTHOUGH LOW LEVEL SHEAR IS MODEST /100 M2/S2 0-1 KM SRH/...A
TORNADO IS POSSIBLE...ESPECIALLY IF A MORE FAVORABLE CONVECTIVE MODE
CAN BE MAINTAINED AS STORMS MOVE INTO THE DISCUSSION AREA.

..SMITH/CORFIDI.. 05/21/2013

ATTN...WFO...LCH...SHV...HGX...FWD...EWX...

LAT...LON 30589692 31549540 30969430 30429698 30589692

Tue May 21, 2013 6:35 pm

Update from Jeff:

Line of severe thunderstorms extends from E of Dallas to N of Austin currently moving E at 30-40mph.

Air mass over the region has become extremely unstable with CAPE values of 3500-4500 J/Kg, but capping layer of warm air in the mid levels continues to inhibit deep convective growth. Vort max rounding the base of the short wave over TX is leading to increasing lift along both the dry line and approaching cold pool from the N helping to break the cap and resulting in a line of severe thunderstorms. Southern end cells have shown some supercell trends, but quickly become outflow dominated and linear which is resulting in a more damaging wind threat than a tornado threat. High resolution meso scale models continue to suggest storms will build SW toward Austin over the next few hours as maximum heating is realized and cap breaks. Line of thunderstorms will then progress quickly into SE TX this evening with a damaging wind and hail threat. Think the highest tornado threat will be now through about 800pm and then a transition to a more linear convective mode and damaging straight line winds. Meso models want to punch this line toward the coast overnight, but I am not confident the cap will break that far south especially given the struggling of storms on the southern flank of the line thus far. With that said, many of the models suggest this idea of storms reaching the coast and cannot deny the agreement.

Will update again this evening if trends suggest more favorable and widespread event for the area and if cap breaks closer to the area.

Tue May 21, 2013 7:18 pm

05212013 ww0208_overview_wou.gif

Tue May 21, 2013 11:09 pm

I'm under a tornado warning

Tue May 21, 2013 11:10 pm

TORNADO WARNING
TXC185-339-471-220430-
/O.NEW.KHGX.TO.W.0009.130522T0355Z-130522T0430Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1055 PM CDT TUE MAY 21 2013

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* TORNADO WARNING FOR...
EAST CENTRAL GRIMES COUNTY IN SOUTHEAST TEXAS...
NORTHERN MONTGOMERY COUNTY IN SOUTHEAST TEXAS...
SOUTHERN WALKER COUNTY IN SOUTHEAST TEXAS...

* UNTIL 1130 PM CDT

* AT 1050 PM CDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM
CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS STORM WAS LOCATED 17
MILES WEST OF NEW WAVERLY...OR 18 MILES WEST OF WILLIS...AND MOVING
EAST AT 25 MPH.

* LOCATIONS IMPACTED INCLUDE...
NEW WAVERLY....RICHARDS...LAKE CONROE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW. MOVE TO A BASEMENT OR AN INTERIOR ROOM ON THE LOWEST
FLOOR OF A STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE HOME OR
OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND PROTECT
YOURSELF FROM FLYING DEBRIS.

&&

LAT...LON 3047 9542 3039 9582 3056 9589 3072 9553
TIME...MOT...LOC 0354Z 250DEG 21KT 3051 9578

$$

May: Isolated Showers To End The Month

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