MESO: Mesoscale Discussion 0277

ACUS11 KWNS 181811
SWOMCD
SPC MCD 181810
ALZ000-MSZ000-LAZ000-ARZ000-181915-

MESOSCALE DISCUSSION 0277
NWS STORM PREDICTION CENTER NORMAN OK
0110 PM CDT MON MAR 18 2013

AREAS AFFECTED...NERN LA...CNTRL MS...NRN AND W-CNTRL AL

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 181810Z - 181915Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...LINE SEGMENTS WITH EMBEDDED BOWS AND MESOCYCLONES ARE
FORECAST TO ENTER PORTIONS OF CNTRL MS AND NRN/W-CNTRL AL THIS
AFTERNOON. ADDITIONAL STORMS MAY FORM TO THE SW OVER PORTIONS OF NRN
LA. PRIMARY SEVERE WEATHER THREATS WILL BE LARGE HAIL AND DAMAGING
WINDS. AREA IS BEING MONITORED FOR A WW.

DISCUSSION...MESOANALYSIS AT 18Z SHOWS A QUASI-STATIONARY FRONTAL
BOUNDARY EXTENDING NEWD FROM NRN LA INTO N-CNTRL AL. REGIONAL RADAR
IMAGERY INDICATES SEVERAL LINES OF STORMS ARE LOCATED ALONG AND N OF
THE FRONT...MOVING E AT AROUND 30 KT. TEMPERATURES ALONG AND S OF
THE FRONT ARE WARMING INTO THE 70S WITH DEWPOINTS IN THE LOW TO MID
60S. VERY STEEP MIDLEVEL LAPSE RATES ARE PRESENT ACROSS THE
AREA...WHICH IS AIDING IN MLCAPE VALUES IN EXCESS OF 1000 J/KG. THE
DESTABILIZING WARM SECTOR MAY PROMOTE SWD PROPAGATION OF ONGOING
LINEAR ACTIVITY INTO CNTRL MS AND W-CNTRL AL...WHILE ALSO ADVANCING
EWD INTO NRN AL. FORCING FOR ASCENT ALONG THE TRAILING FRONTAL
SEGMENT OVER NRN LA MAY ALSO FOCUS ADDITIONAL DEVELOPMENT LATER IN
THE AFTERNOON. MIDLEVEL WSWLY FLOW NEAR 50 KT IS CONTRIBUTING TOWARD
DEEP-LAYER SHEAR PROFILES FAVORABLE FOR BOWING LINE SEGMENTS AND
EMBEDDED MESOCYCLONES...WITH WIND PROFILES BECOMING UNIDIRECTIONAL
AS THE LOW-LEVEL SWLY JET VEERS TO WLY AND WEAKENS SLIGHTLY DURING
THE AFTERNOON. THEREFORE...LARGE HAIL /POSSIBLY NEAR 2 INCHES IN
DIAMETER/ AND DAMAGING WINDS APPEAR TO BE THE PRIMARY SEVERE WEATHER
THREATS.

..GARNER/HART.. 03/18/2013

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

ATTN...WFO...BMX...HUN...MOB...MEG...JAN...

LAT...LON 32058872 32329183 32959183 33709050 33788886 34478703
34958582 33878546 32338717 32058872

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