Texas Severe Weather Thread 2011

[vbhoutex]

I'm waiting for my son to email me a video they got from his wife's cousin's in Denton who lost windows and trees during the storms last night. If I get it I will try to post it here.

[somethingfunny]

FWD NWS Office posted a full time lapse of last night's radar:

[vbhoutex]

Here are some damage pics from Denton

Uploaded with ImageShack.us

[ravyrn]

Looks like another severe weather threat tomorrow.

AS THE SHORTWAVE DISTURBANCE TAKES ON MORE OF A NEGATIVE TILT BY EARLY EVENING...MID LEVEL WIND FIELDS ARE EXPECTED TO INTENSIFY INCREASING DEEP LAYER SHEAR AND THE OVERALL SEVERE WEATHER THREAT ACROSS THE SOUTHERN PLAINS. THE CORE OF THE 500-300PV ANOMALY WILL STAY NORTH ACROSS THE OK/KS BORDER WITH BEST LARGE SCALE FORCING FOR ASCENT NORTH OF THE RED RIVER...HOWEVER LIFT IS EXPECTED TO BE SUFFICIENT ENOUGH TO ERODE CAPPING FARTHER SOUTH INTO NORTH TEXAS BY EARLY EVENING. LATEST ECMWF ALSO SUPPORTS INCREASING LARGE SCALE LIFT ACROSS NORTH TEXAS OVER ITS PREVIOUS RUN. FORECAST SOUNDINGS FROM ACROSS NORTH TEXAS INDICATE THAT THE HIGHEST THREAT FOR THUNDERSTORM DEVELOPMENT WILL BE NORTHEAST OF THE METROPLEX ESPECIALLY IN THE VICINITY OF PARIS/SULPHUR SPRINGS/SHERMAN AREA. NAM12 SOUNDINGS SHOW CAPPING ERODING BY LATE AFTERNOON WITH APPROX 2500 J/KG MLCAPE AND A FAVORABLE HODOGRAPH TO SUPPORT ISOLATED TORNADOES. THE TORNADO THREAT WILL BE HIGHER ACROSS OKLAHOMA AND KANSAS WHERE LOW LEVEL WINDS CAN REMAIN BACKED CLOSER TO THE SURFACE LOW. ACROSS NORTHEAST PORTIONS OF OUR CWA IT WILL BECOME DEPENDENT ON THE LOW LEVEL WIND PROFILE AND MOISTURE CONTENT. THIS IS MOST FAVORABLY DEPICTED BY THE NAM12 WHICH KEEPS SURFACE WINDS MORE BACKED IN VICINITY OF PRESSURE TROF AND FRONT/DRYLINE INTERSECTION. ITS LOW LEVEL MOISTURE PROFILE IS A LITTLE DRY SUPPORTING HIGHER TSTM BASES WHICH MAY BE A LIMITING FACTOR. REGARDLESS...IF CAPPING IS OVERCOME AND STORMS DEVELOP THEY WILL BE SEVERE WITH A LARGE HAIL AND DAMAGING WIND THREAT. AS FOR POPS...WILL ADJUST THE SLIGHT CHANCE POPS BACK JUST A BIT GIVING THE EXPECTED LOCATION OF THE DRYLINE BY LATE AFTERNOON AND WILL CARRY 30/40 POPS ACROSS NORTHEAST PORTIONS OF THE CWA.

[srainhoutx]

Looks like another severe weather threat tomorrow.

NE TX and E OK into AR look interesting for tomorrow.

[somethingfunny]

.UPDATE...
MADE SOME MINOR UPDATES TO TEMPERATURES AND CLOUD COVER TODAY BASED
ON TRENDS. MAIN CONCERN HAS BEEN WHEN AND WHERE THUNDERSTORMS MAY
DEVELOP AS DRY LINE PUSHES EAST INTO THE AREA THIS AFTERNOON.
LOOKS LIKE THE BOUNDARY WILL BE JUST WEST OF THE I-35 CORRIDOR
THIS AFTERNOON WHEN PEAK HEATING IS OCCURRING AND CIN BECOMES
WEAKEST. 12Z NAM AND HIGH RES RR DATA HAVE HINTED AT CONVECTIVE
INITIATION VCNTY DRYLINE IN THE 21-23Z TIME FRAME AND SLIGHTLY
FARTHER WEST THAN PREVIOUS RUNS. HAVE THEREFORE EXPANDED AREA OF
20 POPS WEST-SOUTHWEST SOME TO INCLUDE THE DALLAS-FORT WORTH
METROPLEX WITH THE MENTION OF POSSIBLY SEVERE. THIS EXTENDS
SLIGHTLY FURTHER WEST THAN SPC SLGT RISK AREA BUT FEEL SEVERE
POTENTIAL WILL BE PRESENT BASED ON INSTABILITY AND FOCUS FOR
DEVELOPMENT.

Still at 20% but looking interesting for DFW. We haven't had as much sunshine as I'd like to see for a good cap busting, but there's been enough that we could see them deveop a bit further west between 4 and 6 PM.

[opticsguy]

Fairly new visitor to the site. I have a question about the models, the NAM/WRF in particular.

The last 3 rain events in N. Tx were not predicted by the NAM, and I remember in each case the weather guys on the Dallas channels saying the "cap is to strong", not enough moisture, etc., even 12 hours before these events. Then about 6 hours before the dryline or upper level low passes over, the RUC starts showing that it might rain. The last 3 storms had predicted hundredths of an inch precip. at DFW up to 12 hours beforehand, and in each instance we (I) ended up with 1.5" or rain or more. Last night it hailed pea-to-nickel-size hail for almost 15 minutes and I'm going to have to rake leaves like it's Thanksgiving this weekend.

6 hours before last Sunday's severe storms we were told that DFW wasn't going to get any rain.

To point, the NAM (and GFS) seem to have over-estimated cap strength, underestimated CAPE, or something, much worse than in the previous 15 year's I've been following the models. Has the model changed? Are there more gaps in the initalization data? Has a secret layer of high theta-e appeared at 850 mb due to the GOM oil spill?

[newtotex]

I know this is the Texas thread, but my sister from back home (Tuscaloosa, Ala) sent me pics of tornado damage to our house I thought ya'll might be interested in...how do you post pics on here?

[cheezyWXguy]

I know this is the Texas thread, but my sister from back home (Tuscaloosa, Ala) sent me pics of tornado damage to our house I thought ya'll might be interested in...how do you post pics on here?

If you click the "post reply" button at the bottom of the page, it will take you to a reply page with an imageshack toolbar below the post box, you should see it. All you have to do is click choose file and you can browse your computer for whatever pics you want and upload them

[srainhoutx]

SPC concerning tomorrow (Tuesday)...

FARTHER SOUTH...VERY HOT AFTERNOON TEMPERATURES ACROSS TX WILL
REMOVE THE CAP ALONG THE DRYLINE FROM DFW...SWWD TOWARD AUS. IT/S
NOT ENTIRELY CLEAR HOW MUCH ACTIVITY WILL EVOLVE ALONG THIS BOUNDARY
BUT ANY STORMS THAT DEVELOP WILL DO SO WITHIN A VERY UNSTABLE
AIRMASS AND MORE THAN ADEQUATE DEEP LAYER SHEAR FOR SUPERCELL
DEVELOPMENT AND A THREAT FOR LARGE HAIL AND DAMAGING WINDS. IF IT
BECOMES MORE CLEAR THAT STORMS WILL DEVELOP INTO CNTRL TX THEN A
SLIGHT RISK WILL BE EXTENDED SWWD TO INCLUDE THIS SCENARIO.

[Portastorm]

SPC concerning tomorrow (Tuesday)...

FARTHER SOUTH...VERY HOT AFTERNOON TEMPERATURES ACROSS TX WILL
REMOVE THE CAP ALONG THE DRYLINE FROM DFW...SWWD TOWARD AUS. IT/S
NOT ENTIRELY CLEAR HOW MUCH ACTIVITY WILL EVOLVE ALONG THIS BOUNDARY
BUT ANY STORMS THAT DEVELOP WILL DO SO WITHIN A VERY UNSTABLE
AIRMASS AND MORE THAN ADEQUATE DEEP LAYER SHEAR FOR SUPERCELL
DEVELOPMENT AND A THREAT FOR LARGE HAIL AND DAMAGING WINDS. IF IT
BECOMES MORE CLEAR THAT STORMS WILL DEVELOP INTO CNTRL TX THEN A
SLIGHT RISK WILL BE EXTENDED SWWD TO INCLUDE THIS SCENARIO.

Not that I want to see severe weather ... but we in Austin would welcome some good, old-fashioned thunderstorms. Like most of Texas, we've got toast for grass and fires burning in the area.

[chrisdanger76]

Looks as if the NWS has posted a tornado watch for No. Central Tx until 10pm, wonder if this is overreaction or are we actually going to see some severe weather this evening?

[somethingfunny]

It's not the most pronounced hook echo I've ever seen, but Atoka, OK sure doesn't need another severe storm right now.

The radar is blurry because southeastern Oklahoma and northeastern Texas are in a "radar blind spot" that makes it impossible to see what's going on at the lowest levels of the atmosphere -- they're far enough away from the OKC/Tulsa/DFW/Ft.Smith/Shreveport radar sites that the curvature of the earth only allows the radar echoes to see the upper levels of the storms.





^ The Atoka County cell with the tornado warning is the northernmost one at the very edge of the radar's reach.

[somethingfunny]

Severe thunderstorm warnings are now up for Denton and Grayson counties, and Bryan county across the river too.

[srainhoutx]

MESOSCALE DISCUSSION 0492
NWS STORM PREDICTION CENTER NORMAN OK
0152 PM CDT WED APR 20 2011

AREAS AFFECTED...TX HILL COUNTRY

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 201852Z - 201945Z

ISOLD-WIDELY SCATTERED SEVERE STORMS EXPECTED TO DEVELOP THIS
AFTERNOON. CONVECTIVE INITIATION EXPECTED FIRST /AROUND 20Z/ NEAR A
MESOLOW-TRIPLE POINT INVOF THE WRN PORTION OF THE TX HILL COUNTRY.
LARGE TO VERY LARGE HAIL AND DMGG WIND WILL BE THE MAIN THREATS.

18Z SURFACE ANALYSIS PLACES A 1008 MB LOW 35 MI SSW SJT WHERE A N-S
DRYLINE IS INTERSECTING A STALLED FRONT ELONGATED FROM THE PECOS
RIVER VALLEY NEWD INTO NERN TX. THIS IS WHERE WEAK CONVERGENCE IN
ADDITION TO HEATING ARE LEADING TO THE DEVELOPMENT OF A SWELLING CU
FIELD NEAR AND ALONG THE AFOREMENTIONED BOUNDARIES. THE WARM/MOIST
SECTOR IS HEATING CONSIDERABLY AS TEMPS WARM WELL INTO THE 80-90S
AMIDST MID-UPPER 60S DEWPOINTS. THIS IS CONTRIBUTING TO A VERY
UNSTABLE AIRMASS WITH 3000-4000 J/KG MLCAPE PER OBJECTIVE ANALYSIS.
RECENT RUNS OF THE HRRR SEEM TO RESOLVE WEAKENING INHIBITION INVOF
THE SWELLING CU FIELD...AND SUGGEST CONVECTIVE INITIATION MAY OCCUR
AROUND 20Z.

ALTHOUGH MID-HIGH LEVEL FLOW IS RATHER MARGINAL...MODEL FORECAST
SOUNDINGS SHOW STRENGTHENING SELY LOW LEVEL FLOW TOWARDS THE LATE
AFTERNOON/EVENING HOURS. THIS WILL ACT TO ENHANCE EFFECTIVE SHEAR
ON THE ORDER OF 30-40 KTS...SUFFICIENT FOR ORGANIZED STORMS. GIVEN
THE MAGNITUDE OF INSTABILITY COUPLED WITH INCREASING DEEP LAYER
SHEAR...A FEW SUPERCELLS CAPABLE OF LARGE TO VERY LARGE HAIL...DMGG
WINDS ARE POSSIBLE THIS AFTERNOON INTO THE EARLY EVENING HOURS.

..SMITH.. 04/20/2011


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

[DonWrk]

Could someone tell me what the best premium weather service is? Or is it even worth paying for? I'm looking for something more towards good maps, and very long radar loops. Thanks.

[srainhoutx]

MESOSCALE DISCUSSION 0504
NWS STORM PREDICTION CENTER NORMAN OK
0219 PM CDT THU APR 21 2011

AREAS AFFECTED...TX PECOS RIVER VALLEY

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 211919Z - 212015Z

STORM INITIATION IS EXPECTED WITHIN THE NEXT HOUR OR SO ACROSS THE
TX PECOS RIVER VALLEY. SUPERCELLS CAPABLE OF LARGE TO VERY LARGE
HAIL AND DMGG WINDS WILL BE THE PRIMARY HAZARDS. A WW MAY BE
REQUIRED TO ADDRESS THIS THREAT AND THE 20Z CONVECTIVE OUTLOOK
UPDATE WILL INCLUDE THIS AREA IN A SLIGHT RISK.

WATER VAPOR TRENDS THE PAST FEW HOURS SHOWS A WEAK IMPULSE MOVING
ACROSS ERN NM AND PARTS OF W TX. THIS IS EVIDENT IN WSM PROFILER
TIME SERIES WITH FLOW INCREASING BY 20 KTS IN THE MID-UPPER LEVELS
SINCE THIS MORNING. ASCENT ASSOCIATED WITH THIS FEATURE...IMPLIED
BY EWD MOVING BROKEN CIRRUS SHIELD...IS NOW SPREADING TOWARDS THE S
PLAINS AND THE LOWER PECOS RIVER VALLEY. LATEST SURFACE ANALYSIS
SHOWS 1MB/HR SURFACE PRESSURE FALLS THE PAST FEW HOURS SEEMINGLY
REFLECTIVE OF THE UPPER FEATURE WITH RICH LOW LEVEL MOISTURE
CHARACTERIZED BY MID 60S DEWPOINTS HOLDING ACROSS THE LOWER PECOS
RIVER VALLEY IN SWRN TX. STRONG HEATING ACROSS THE
REGION...PREFERABLY FAVORING HIGHER TERRAIN/ HAS ESSENTIALLY
WEAKENED THE REMAINING CAP. AS SUCH...EXPECTING STORM INITIATION BY
20Z NEAR THE GLASS MTNS AND FST.

VERY STEEP LAPSE RATE ENVIRONMENT ATOP THE AFOREMENTIONED MOIST
BOUNDARY LAYER HAS LED TO A VERY UNSTABLE AIRMASS /3500 J/KG MLCAPE
PER OBJECTIVE ANALYSIS/. MOIST SELY UPSLOPE FLOW UNDERNEATH
INCREASING DEEP LAYER SHEAR WILL BE SUPPORTIVE OF A SUPERCELL WIND
PROFILE AND RESULT IN STORMS RAPIDLY DEVELOPING AND BEING CAPABLE OF
LARGE TO VERY LARGE HAIL AND DMGG WINDS ONCE SUPERCELL STRUCTURE IS
ATTAINED. ALTHOUGH ONLY ISOLD STORM COVERAGE IS EXPECTED...THE
NATURE OF THE THREAT MAY WARRANT A WW ISSUANCE WITHIN THE NEXT HOUR
OR TWO.

..SMITH.. 04/21/2011


ATTN...WFO...EWX...SJT...LUB...MAF...

[somethingfunny]

Found this disturbing tidbit in this afternoon's AFD from Fort Worth:

FOR THE FIRST TIME IN THE 12-YEAR HISTORY OF THE U.S. DROUGHT
MONITOR...THE ENTIRE STATE OF TEXAS IS IN DROUGHT. TWO THIRDS OF
TEXAS IS CATEGORIZED AS BEING IN EXTREME (D3) OR EXCEPTIONAL
DROUGHT (D4)...THE GREATEST EXTENT ON RECORD.

[ravyrn]

So in the last hour on the Ft Worth NWS graphic I've seen 3 tornado warnings, so why wouldn't they put up a tornado watch for the area?

[somethingfunny]