MESO: Mesoscale Discussion 0564

ACUS11 KWNS 272037
SWOMCD
SPC MCD 272036
TXZ000-272200-

MESOSCALE DISCUSSION 0564
NWS STORM PREDICTION CENTER NORMAN OK
0336 PM CDT SAT APR 27 2013

AREAS AFFECTED...SRN EDWARDS PLATEAU INTO NRN PARTS OF SOUTH CENTRAL
AND SOUTH TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 272036Z - 272200Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...THE SRN EDWARDS PLATEAU INTO NRN PORTIONS OF SOUTH CENTRAL
AND SOUTH TX ARE BEING MONITORED FOR CONVECTIVE DEVELOPMENT THIS
AFTERNOON...AND THE POTENTIAL NEED FOR A ONE OR MORE WATCHES.
TRENDS WITH TSTM DEVELOPMENT OVER THE HIGHER TERRAIN OF COAHUILA
MEXICO WILL NEED TO BE MONITORED AS WELL FOR POTENTIAL SEVERE
WEATHER THREAT...IF ACTIVITY CAN REACH THE LOWER RIO GRANDE VALLEY
AREA OF S TX.

DISCUSSION...EARLY-MID AFTERNOON SURFACE ANALYSES INDICATED A FRONT
CONTINUED TO MOVE SLOWLY E/SEWD ACROSS ERN AND CENTRAL TX. AT
20Z...THIS BOUNDARY EXTENDED FROM THE ARKLATEX REGION SWWD TO 50 S
OF KCRS...AND THEN WSWWD ACROSS THE SRN EXTENT OF THE EDWARDS
PLATEAU TO THE RIO GRANDE RIVER VICINITY OF WRN VAL VERDE COUNTY. A
MOIST/WARM BOUNDARY LAYER WITH SURFACE TEMPERATURES IN THE UPPER 70S
TO LOWER 80S ALONG AND S OF THE FRONT IS CONTRIBUTING TO MODERATE
INSTABILITY /MLCAPE 2000-2500 J PER KG/...GIVEN THE PRESENCE OF
STEEP MIDLEVEL LAPSE RATES.

OBJECTIVE ANALYSES INDICATED WEAK DEEP LAYER CONVERGENCE ALONG THE
FRONT WHICH APPEARS TO BE LIMITING THE DEVELOPMENT OF SURFACE BASED
CONVECTION THUS FAR ACROSS THE DISCUSSION AREA. REGIONAL RADAR
IMAGERY SHOWED A COUPLE OF TSTMS HAD DEVELOPED WITHIN A PLUME OF
ELEVATED CONVECTION N OF THE FRONT THIS AFTERNOON. THE MOST RECENT
STORMS COULD BE NEARLY SURFACE BASED IN WILLIAMSON AND TRAVIS
COUNTIES TX...GIVEN ITS LOCATION NEAR THE FRONT. ADDITIONAL STORMS
LOCATED TO THE NW TO W OF THE HOUSTON METRO AREA SHOULD CONTINUE TO
PROPAGATE NWWD LATE THIS AFTERNOON INTO A MORE FAVORABLE CAPE/SHEAR
SPACE SUPPORTIVE OF MORE PERSISTENT/ORGANIZED UPDRAFTS THAT COULD
RESULT IN A HAIL THREAT.

MEANWHILE...IF GREATER COVERAGE OF CONVECTIVE DEVELOPMENT OCCURS
NEAR AND S OF THE FRONT...THE PRESENCE OF STRONG INSTABILITY AND
EFFECTIVE BULK SHEAR OF 30-40 KT WILL SUPPORT ORGANIZED STRONG TO
SEVERE STORMS. THUS...THE DISCUSSION AREA IS BEING MONITORED FOR
THE POTENTIAL ISSUANCE OF ONE OR MORE WATCHES.

..PETERS/HART.. 04/27/2013

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

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

LAT...LON 29840146 30060061 30299970 30519857 30929751 31119673
31189633 31329565 30759536 30349553 30069603 29629747
29339840 29179944 29149969 29010016 28860053 29190087
29650143 29840146

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