MESO: Mesoscale Discussion 0368

ACUS11 KWNS 020821
SWOMCD
SPC MCD 020820
TXZ000-021015-

MESOSCALE DISCUSSION 0368
NWS STORM PREDICTION CENTER NORMAN OK
0320 AM CDT TUE APR 02 2013

AREAS AFFECTED...PORTIONS CENTRAL TX.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 020820Z - 021015Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...ISOLATED SVR THREAT CONTINUES WITH SVR TSTMS INITIALLY
OVER ERATH/COMANCHE COUNTIES. THIS ACTIVITY IS FCST TO MOVE ESEWD
TO SEWD ACROSS PORTIONS CENTRAL TX...POSING THREAT FOR OCNL HAIL AND
DAMAGING WINDS. LOW/CONDITIONAL POTENTIAL EXISTS FOR MORE
WIDESPREAD/ORGANIZED SVR THREAT IN CORRIDOR EXTENDING INTO SE TX.
AS LONG AS CONVECTION REMAINS RELATIVELY SMALL AND SVR THREAT
MRGL...WW IS NOT ANTICIPATED. HOWEVER...ACTIVITY WILL BE MONITORED
FOR STORM-SCALE/UPSCALE GROWTH AND ASSOCIATED COLD-POOL ORGANIZATION
THAT WOULD INDICATE GREATER AREAL COVERAGE OF SVR WIND THREAT IN
PARTICULAR.

DISCUSSION...SFC MESOANALYSIS SHOWS WARM FRONT FROM BPT AREA NWWD TO
WRN PORTIONS DFW METROPLEX...INTERSECTING SYNOPTIC COLD FRONT
BETWEEN MWL-DTO. WARM FRONT IS DRIFTING NWD. OUTFLOW BOUNDARY ARCS
ACROSS ERATH/COMANCHE COUNTIES...AND IS BEING SHIFTED SEWD BY
ONGOING CONVECTION. PERSISTENT CLUSTER OF TSTMS OVER THOSE COUNTIES
HAS EVOLVED AS OF 08Z SUCH THAT
1. INITIAL SVR STORM SW OF WARM FRONT HAS NEARLY DISSIPATED AND
BECOME ENTRAINED WITHIN WARM-ADVECTION WING OF
2. LOOSELY ORGANIZED MULTICELL WITH INTERMITTENT BOWING AND
WEAK-MESOCYCLONE CHARACTERISTICS. THIS CONVECTION DEVELOPED OVER
TOP OF OUTFLOW FROM INITIAL STORM...BUT NOW APPEARS TO HAVE REACHED
SFC WARM SECTOR AND IS MOVING ESEWD ABOUT 20 KT. SOME POTENTIAL
EXISTS FOR THIS ACTIVITY TO EXPAND AND PRODUCE DAMAGING GUSTS ALONG
AND S OF WARM FRONT...HOWEVER THIS THREAT IS VERY CONDITIONAL ATTM.

MODIFIED RAOBS AND FCST SOUNDINGS SHOW PLUME OF RELATIVELY STEEP
MIDLEVEL LAPSE RATES OVER THIS REGION OVERLYING 60-63 F SFC DEW
POINTS S OF WARM FRONT. THIS LEADS TO MLCAPE 500-1200
J/KG...DECREASING RAPIDLY N OF WARM FRONT. CAPE ALSO
DIMINISHES...WITH SUBSTANTIALLY INCREASING MLCINH...DOWNSHEAR ALONG
WARM FRONT WHERE LOW-LEVEL THETAE IS WEAKER. THAT IS ONE LIMITING
FACTOR...AS IS CURRENT TENDENCY FOR SUPPORTIVE LLJ TO WEAKEN WITH
EWD EXTENT. LLJ GEOMETRY GENERALLY WILL BE MAINTAINED THROUGH
REMAINDER PRE-DAWN HOURS AS HEIGHTS FALL ALOFT IN ADVANCE OF
GREAT-BASIN CYCLONE...HOWEVER ITS MAGNITUDE WILL WEAKEN GRADUALLY.
CONTINUED DIABATIC SFC COOLING ALSO WILL RESULT IN GREATER STATIC
STABILITY WITH TIME...ESPECIALLY IN AREAS E OF I-35. FINALLY...DEEP
SHEAR AND MEAN-WIND VECTORS EACH ARE MODEST...WITH EFFECTIVE SHEAR
MAGNITUDES ONLY IN 25-30 KT RANGE AND MIDLEVEL FLOW ONLY 10-15 KT.
STORM-SCALE PROCESSES WILL NEED TO MANUFACTURE
INTENSE/PRECIP-LOADING-DRIVEN COLD POOL IN ORDER TO IMPART ENOUGH
FORCED ASCENT TO GROW THIS CONVECTION AT MORE THAN MRGL SVR
LEVELS...INTO WHAT APPEARS TO BE MORE UNFAVORABLE ENVIRONMENT WITH
SEWD EXTENT.

..EDWARDS/KERR.. 04/02/2013

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

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

LAT...LON 31809847 31999822 32249801 32099737 31809640 31379556
30289685 31709843 31809847

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