MESO: Mesoscale Discussion 0337

ACUS11 KWNS 300621
SWOMCD
SPC MCD 300621
TXZ000-OKZ000-300815-

MESOSCALE DISCUSSION 0337
NWS STORM PREDICTION CENTER NORMAN OK
0121 AM CDT SAT MAR 30 2013

AREAS AFFECTED...PORTIONS N TX AND EXTREME SRN OK.

CONCERNING...SEVERE THUNDERSTORM WATCH 65...

VALID 300621Z - 300815Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 65
CONTINUES.

SUMMARY...GUSTS APCHG SVR LEVELS...WITH ISOLATED DAMAGE...CANNOT BE
RULED OUT AS BAND OF TSTMS WITH EMBEDDED LEWP FEATURES MOVES ESEWD
ACROSS DFW METROPLEX AND SURROUNDING COUNTIES. HOWEVER...ORGANIZED
SVR THREAT APPEARS TOO LOW TO WARRANT ADDITIONAL WW ATTM.
ISOLATED/ELEVATED TSTMS MAY DEVELOP BEHIND MCS AND ATOP ITS
OUTFLOW...BUT ANY ACCOMPANYING HAIL THREAT LIKEWISE APPEARS MRGL.
AS SUCH...WW MAY BE CLEARED BEHIND COMPLEX AND OVER OK COUNTIES THAT
APPEAR LIKELY TO BE MISSED BY MCS.

DISCUSSION...SFC MESOANALYSIS SHOWS MOIST AXIS FROM AROUND WISE
COUNTY TX SSEWD TO UPPER TX COAST W OF I-45. BROAD/30-40 KT SSWLY
LLJ IS EVIDENT VIA VWP...INDICATING SUPPORTIVE WAA AND MOISTURE
TRANSPORT ABOVE SFC FOR CONTINUED ESEWD MOTION OF TSTM COMPLEX
THROUGH METROPLEX. LLJ IS FCST TO VEER AND WEAKEN STARTING IN
09-10Z TIME FRAME.

BOUNDARY-LAYER THETAE SHOULD DIMINISH WITH EWD EXTENT...AND WITH
TIME...INCREASING MLCINH. MODIFIED FCST SOUNDINGS STILL SHOW
SFC-BASED EFFECTIVE INFLOW PARCELS...OR VERY NEARLY SO...BUT WITH
MLCINH INCREASING BY THE HOUR. GIVEN 1) LACK OF MORE WELL-DEVELOPED
COLD-POOL PERTURBATION AND 2) RELATIVELY LOW DEW-POINT DEPRESSIONS
AND INCREASINGLY STABLE CONDITIONS IN BOUNDARY LAYER DUE TO DIABATIC
SFC COOLING...MAIN FORCING MECHANISM FOR STG TO DAMAGING SFC GUSTS
WOULD BE PRECIP LOADING. THESE TRENDS AND PROCESSES INDICATE THREAT
IS LOCALIZED AND TRANSIENT...BUT NON-ZERO...AND RELATIVELY MAXIMIZED
IN ANY SMALL BOWS OR EMBEDDED LEWPS/SMALL BOWS. ONE OF THOSE
PRODUCED SUB-SVR/41-KT GUST AT MWL AT 603Z. OVERALL WEAKENING
TENDENCY IS EXPECTED AFTER ABOUT 08Z...WHICH IS ALSO NOMINAL
EXPIRATION TIME OF WW.

..EDWARDS.. 03/30/2013

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

ATTN...WFO...FWD...OUN...

LAT...LON 32669902 33149772 33819679 33999632 33859578 32809613
31919722 32489876 32669902

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