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Weekend Severe Possibilities (2/9-10)


OKpowdah

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AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE SAN ANGELO TX

452 AM CST SAT FEB 9 2013

.SHORT TERM...

EXPECT STRONG WINDS TODAY AND A POTENTIAL FOR SEVERE THUNDERSTORMS

TONIGHT WITH LARGE HAIL...DAMAGING WINDS AND ISOLATED TORNADOES

ACROSS MUCH OF WEST CENTRAL TEXAS.

AS A POTENT UPPER LEVEL SHORTWAVE TROUGH...POWERED BY A 120KT UPPER

LEVEL JET MAX...MOVES INTO WEST CENTRAL TEXAS TONIGHT...THE SURFACE

PRESSURE GRADIENT WILL TIGHTEN TODAY RESULTING IN STRONG WINDS OF 30

TO 40 MPH WINDS BETWEEN 9AM AND 6PM ALONG AND WEST OF A LINE FROM

HASKELL TO ABILENE TO EDEN TO SONORA. WE ARE PLANNING TO ISSUE A

WIND ADVISORY FOR THIS AREA AND A LAKE ADVISORY EAST OF THIS LINE.

THE STRONG UPPER LEVEL SHORTWAVE TROUGH WILL ALSO PUSH A DRYLINE AND

COLD FRONT INTO THE REGION TONIGHT THAT WILL SERVE AS A TRIGGER FOR

STORMS AS THEY COLLIDE WITH THE MOISTURE FROM THE GULF OF MEXICO.

LATEST MODELS SHOW THE DRYLINE/FRONTAL BOUNDARY MOVING INTO WC TX

AFTER 6PM. LATEST NAM MODEL SOUNDING DATA SHOWS 55 TO 60KTS OF 0 TO

6KM BULK SHEAR...MOST UNSTABLE CAPE VALUES OF 500 TO 1200J/KG

FROM WEST TO EAST.

THE BEST SEVERE WEATHER PARAMETERS ARE PROGGED TO BE ALONG AND EAST

OF A LINE FROM BROWNWOOD TO SONORA AFTER MIDNIGHT. THIS IS WHERE

THE BEST LIFT AND THE STRONGEST UPDRAFTS WILL BE SUPPORTED BY

MUCAPE VALUES OF 1200 J/KG...0 TO 6KM BULK SHEAR OF 55 TO

60KTS...AND DEWPOINTS IN THE LOWER 60S. A FEW OF THE SOUNDINGS

ACROSS THE NORTHWEST HILL COUNTRY DID SHOW SOME WEAK CAPPING. DO

PLAN TO HIGHLIGHT THIS AREA IN THE FORECAST...HWO AND THE

GRAPHICAST.

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DAY 2 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   1130 AM CST SAT FEB 09 2013
  
   VALID 101200Z - 111200Z
  
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM E TX ACROSS THE LOWER MS
   VALLEY AND INTO WRN AL...
  
   ...SYNOPSIS...
   A POTENT UPPER TROUGH WILL MOVE SLOWLY EWD ACROSS THE PLAINS AND MS
   VALLEY WITH STRENGTHENING MID TO UPPER LEVEL FLOW EXPANDING SWD TO
   THE GULF COAST. AT THE SURFACE...LOW PRESSURE WILL MOVE FROM ERN NEB
   INTO IA BY 00Z...WITH A COLD FRONT EXTENDING ROUGHLY FROM STL TO MEM
   TO HOU. PRECEDING THE COLD FRONT...A WARM FRONT WILL LIFT NWD ACROSS
   THE LOWER MS VALLEY AND WILL ALLOW A MORE MOIST AND UNSTABLE AIR
   MASS TO SPREAD NWD ACROSS LA...SRN AR...MS...AND AL WITH BOUNDARY
   LAYER DEWPOINTS RISING INTO THE MID 60S F. THESE BOUNDARIES...AS
   WELL AS POTENTIAL OUTFLOW BOUNDARIES...WILL SERVE AS PRIMARY FOCI
   FOR SEVERE WEATHER.
  
   ...ARKLATEX INTO THE LOWER MS VALLEY...
   THUNDERSTORMS SHOULD BE ONGOING AT 12Z ALONG THE COLD FRONT FROM WRN
   AR/SERN OK INTO NERN TX. THE ENVIRONMENT WILL ALREADY BE STRONGLY
   SHEARED...AND THESE STORMS MAY BE SEVERE PRODUCING MAINLY DAMAGING
   WINDS. MODELS ARE IN GOOD AGREEMENT IN DEPICTING INCREASING DEEP
   DIFFERENTIAL DIVERGENCE SPREADING EWD AND LIKELY ENHANCING SOME OF
   THIS CONVECTION...THUS THE DAMAGING WIND THREAT MAY INCREASE WITH
   TIME ACROSS SRN AR...NERN TX AND NRN LA THROUGH EARLY AFTERNOON.
  
   MEANWHILE...THE AIR MASS WILL DESTABILIZE S OF THE WARM FRONT MAINLY
   THROUGH THETA-E ADVECTION AS HEATING SHOULD BE QUITE LIMITED.
   ALTHOUGH CAPPED EARLY...THE SLOW MOVEMENT OF THE COLD FRONT WILL
   ALLOW THE MOIST BOUNDARY LAYER TO DEEPEN THROUGH THE DAY. STRONGLY
   VEERING LOW LEVEL WINDS WILL BE FAVORABLE FOR TORNADIC
   SUPERCELLS...AND THERE APPEARS TO BE A CORRIDOR OF MAXIMUM TORNADO
   PROBABILITY FROM NERN LA INTO MUCH OF CNTRL MS...IMMEDIATELY S OF/OR
   AHEAD OF THE POTENTIAL AR/NRN MS MCS. WITH LARGE LOOPING
   HODOGRAPHS...A COUPLE STRONG TORNADOES COULD OCCUR. UNCERTAINTY
   REGARDING SEVERE COVERAGE AHEAD OF THE COLD FRONT ACTIVITY PRECLUDES
   HIGHER OVERALL PROBABILITIES AT THIS TIME.
  
   ..JEWELL.. 02/09/2013

 

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Beautiful hodographs across LA/AR/MS tomorrow.  Some hi-res meso models want to pop some discrete stuff ahead of the qlcsc/squall line. Could be quite a significant day locally with strong/violent tornadoes not out of the question IMO, with Tds >=60F and open hodographs.  SREFs also eating up this area as well.

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Golfballs being reported with that cell along with hail covering 287. That cell had an explosive initiation  Very impressive for February to say the least. 

 

Hindsight is 20/20... that alone probably would've been worth the drive out for me. Then again, I have some friends who did go out today and they turned around at sunset, so at least things could be worse than us staying home. ;)

 

As paltry as the sfc theta-e is in the current storm environment, it should drop off rather quickly as they haul east and outpace the dryline. Of course, they may already be slightly elevated.

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Severe warnings now issued in LBB's area. Not sure why SPC moved the severe east. Didn't agree with that.

I was surprised to see that they even took away sub-risk worthy probs. Nonetheless, the line quickly weakened after pushing away from the marginal environment.

 

Looks like a nice sub-severe line recently developed in your area.

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I was surprised to see that they even took away sub-risk worthy probs. Nonetheless, the line quickly weakened after pushing away from the marginal environment.

 

Looks like a nice sub-severe line recently developed in your area.

Looks like that line is grabbing a gear now that it has pushed just east of San Angelo to Abilene, 7 severe warnings out now.

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Is that a hook developing on I-10 NW of San Antonio somewhere near Junction?

 

ETA

 

SEVERE THUNDERSTORM WARNING
TXC171-100815-
/O.NEW.KEWX.SV.W.0001.130210T0723Z-130210T0815Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
123 AM CST SUN FEB 10 2013

THE NATIONAL WEATHER SERVICE IN AUSTIN SAN ANTONIO HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  GILLESPIE COUNTY...

* UNTIL 215 AM CST.

* AT 121 AM CST...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 6 MILES WEST OF
  TIVYDALE...OR 13 MILES NORTH OF KERRVILLE...AND MOVING EAST AT 45
  MPH.

* SOME LOCATIONS IN THE WARNING INCLUDE CHERRY SPRING...HILLTOP...
  FREDERICKSBURG...GRAPETOWN...CAIN CITY...ROCKY HILL... LUCKENBACH ...
  CRABAPPLE...BLUMENTHAL...ECKERT...STONEWALL AND WILLOW CITY.

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I am assuming, despite apparent surface based CAPE, and based on what is labeled as a 6Z (Midnight) balloon release from CLL (not a normal sounding sight, but the met school has some) the lead cells haven't produced because of the 850 mb warm nose and mediocre low level lapse rates.  Plenty of mid level speed shear and instability.

 

6Z balloon sounding graphic from KCLL on KHOU-TV local wx forum.

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It has rotation looking at free NWS radar products.  The model sounding for 15Z (above) has much less of a warm nose than the 6Z CLL sounding.  I wish they'd transmit those to SPC, I see only 0Z soundings on their page.   Just checking 7Z model sounding for CLL, it compares well to the 6Z balloon, and SPC mesoanalysis page shows the 2 cells developing very near the edge of where CINH drops below -25 J/Kg.

 

 

ETA

 

Further North, nice little kinks in line moving through Metroplex, severe warned.

 

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FORT WORTH TX
225 AM CST SUN FEB 10 2013

..TIME..    ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE..    ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0224 AM     TSTM WND GST     SAGINAW                 32.87N  97.37W
02/10/2013  E60 MPH          TARRANT            TX   TRAINED SPOTTER

            LONGHORN AT NORTH MAIN

$$
 

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It has had 'the look' several times all evening, late night/early morning, but has apparently not produced beyond 1.5 inch hail.

 

 

 

 

 

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
332 AM CST SUN FEB 10 2013

THE NATIONAL WEATHER SERVICE IN AUSTIN SAN ANTONIO HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHERN WILLIAMSON COUNTY...

* UNTIL 415 AM CST.

* AT 326 AM CST...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 LIBERTY
  HILL...OR 10 MILES WEST OF SERENADA...AND MOVING NORTHEAST AT 55
  MPH.

* SOME LOCATIONS IN THE WARNING INCLUDE ANDICE...GEORGETOWN DAM...SUN
  CITY...GEORGETOWN...FLORENCE...WEIR AND JARRELL.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DOPPLER RADAR HAS DETECTED ROTATION WITHIN THIS STORM. ALTHOUGH NOT
IMMEDIATELY LIKELY...IF A TORNADO IS SPOTTED...ACT QUICKLY AND MOVE
TO A PLACE OF SAFETY IN A STURDY STRUCTURE...SUCH AS A BASEMENT OR
SMALL INTERIOR ROOM.

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BULLETIN - EAS ACTIVATION REQUESTED

TORNADO WARNING

NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX

340 AM CST SUN FEB 10 2013

THE NATIONAL WEATHER SERVICE IN AUSTIN SAN ANTONIO HAS ISSUED A

* TORNADO WARNING FOR...

NORTHERN WILLIAMSON COUNTY...

* UNTIL 415 AM CST.

* AT 335 AM CST...NWS METEOROLOGISTS HAVE DETECTED A SEVERE

THUNDERSTORM CAPABLE OF PRODUCING A TORNADO NEAR SUN CITY...OR

ABOUT 6 MILES WEST OF SERENADA...MOVING NORTHEAST AT 50 MPH.

* SOME LOCATIONS IN THE WARNING INCLUDE SUN CITY...SERANADA...

WEIR...WALBURG AND JARRELL.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF YOU ARE IN A MOBILE HOME OR VEHICLE...GET OUT AND GO TO A STURDY

SHELTER. IF NO SHELTER IS AVAILABLE...LIE FLAT IN THE NEAREST DITCH

OR OTHER LOW SPOT AND COVER YOUR HEAD WITH YOUR HANDS.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 900 AM CST SUNDAY MORNING FOR

SOUTH CENTRAL TEXAS.

 

Familiar name there.

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Snippet from latest D1.

CELLS OVER SERN LA AND SRN MS APPEAR TO BE ELEVATED AND NOT TAKING
ADVANTAGE OF THE LOWER PORTION OF THE HODOGRAPH. HOWEVER...LOW LEVEL
MOISTURE ADVECTION WILL PERSIST...AND CELLS COULD CHANGE CHARACTER
LATER THIS AFTERNOON...ESPECIALLY THE SWRN-MOST CELLS CLOSEST TO THE
WARMER AIR. STRONGER STORMS ALONG THE MAIN LINE COULD BRIEFLY
INCREASE IN INTENSITY AS WELL.

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