Mesoscale Discussion 313

Issued

Mar 29, 2011, 10:15 PM CDT (03:15 UTC)

Expired

Mar 29, 2011, 11:45 PM CDT

In force

90 min

Issued by

the Storm Prediction Center

The Houston radar (KHGX), 149 km from the middle of the area, began a volume at 03:16 UTC, the scan nearest the moment this went out.

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• Severe Thunderstorm Watch 77Mar 29, 10:50 PM CDT

440 
ACUS11 KWNS 300315
SWOMCD
SPC MCD 300315 
LAZ000-TXZ000-300445-

MESOSCALE DISCUSSION 0313
NWS STORM PREDICTION CENTER NORMAN OK
1015 PM CDT TUE MAR 29 2011

AREAS AFFECTED...PORTIONS S TX...SWRN/S-CENTRAL LA.

CONCERNING...SEVERE THUNDERSTORM WATCH 73...75...

VALID 300315Z - 300445Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
73...75...CONTINUES.

CONTINUE WW 73.  WW 75 IS SLATED TO EXPIRE AT 04Z...HOWEVER SRN
PORTIONS MAY NEED TO BE REPLACED BEFORE THEN...PENDING ADDITIONAL
SCRUTINY OF CONVECTIVE/ENVIRONMENTAL TRENDS.

ISOLATED...APPARENTLY SVR TSTM WITH INTERMITTENT SUPERCELLULAR
MORPHOLOGY...WHICH DEVELOPED ALONG ERN SLOPES OF SERRANIAS DEL BURRO
RANGE IN MEX...IS AFFECTING EAGLE PASS AREA ATTM.  THIS
ACTIVITY...ALONG WITH OTHER CONVECTION DEVELOPING TO ITS SE AND
SW...MAY GROW UPSCALE AND PERSIST FOR A FEW MORE HOURS...MOVING
ESEWD IN STEP WITH SFC COLD FRONT.  FOREGOING AIR MASS WILL BE
CHARACTERIZED BY MLCAPE 1000-2000 J/KG MLCAPE AND 45-55 KT EFFECTIVE
SHEAR MAGNITUDES.  WEAK LOW-LEVEL WINDS WILL CONTINUE TO LIMIT
NEAR-SFC HODOGRAPH SIZE.  FRONTAL MAX IN LOW-LEVEL ASCENT WILL HELP
TO OVERCOME WHAT SHOULD BE GRADUAL INCREASE WITH TIME IN MLCINH IN
PROSPECTIVE INFLOW REGION...CASTING CONSIDERABLE UNCERTAINTY AS TO
HOW LONG THIS ACTIVITY WILL LAST.  TYPICALLY...SUCH COMPLEXES IN
THIS AREA AND IN SIMILAR REGIMES PRODUCE SVR ALONG WELL-DEFINED
SWATH...BUT OFTEN DISSIPATE ABRUPTLY AMIDST AMBIENT STRENGTHENING OF
BOUNDARY-LAYER CAPPING.  RELATIVE WEAKNESS IN MLCINH CURRENTLY
EVIDENT N OF CRP-LRD LINE INDICATES CONVECTION MAY PERSIST ACROSS
MUCH OF PROJECTED PATH TOWARD COAST...THEREFORE SMALL WW MAY BE
REQUIRED.  SVR THREAT FROM ISOLATED/POSTFRONTAL/LEFT-MOVING TSTM
NEAR DRT SHOULD BE MORE TRANSIENT/ISOLATED.

MEANWHILE...STG-SVR TSTMS ARE INCREASING SUBSTANTIALLY IN COVERAGE
OVER ERN PORTIONS WW 75...ACROSS SERN LA...WITH SIMILAR TRENDS
POSSIBLE OVER PORTIONS SE TX AS WELL.  COLD FRONT -- ANALYZED AT 03Z
FROM EAGLE PASS STORM ENEWD OVER ATASCOSA/HARRIS/NEWTON COUNTIES TX
AND VERNON PARISH LA -- WILL KEEP MOVING SEWD ABOUT 20 KT ACROSS
THIS REGION...PROVIDING PRIMARY FOCUS FOR CONVECTIVE DEVELOPMENT SFC
AND ALOFT.

..EDWARDS.. 03/30/2011

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...JAN...LCH...SHV...HGX...CRP...EWX...BRO...

LAT...LON   29280088 29590042 29569818 30699450 31519266 31419187
            29469186 29589214 29519228 29569270 29769323 29739379
            29659380 29649412 29479460 28919529 28449628 27949695
            27239736 27319958 27399946 27569953 27659974 27799988
            28140007 28390036 29110068 29280088

Mesoscale Discussions in Texas, 2011Mesoscale Discussions in Louisiana, 2011Every mesoscale discussion in 2011

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.