MESO: Mesoscale Discussion 0670

ACUS11 KWNS 172100
SWOMCD
SPC MCD 172100
MSZ000-ARZ000-LAZ000-172200-

MESOSCALE DISCUSSION 0670
NWS STORM PREDICTION CENTER NORMAN OK
0400 PM CDT FRI MAY 17 2013

AREAS AFFECTED...AR...LA...MS

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 172100Z - 172200Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THERE IS A CHANCE THAT STORMS WILL INCREASE IN COVERAGE
WHILE DRIFTING SEWD ACROSS THE DELTA REGION THROUGH THE EVENING.
TRENDS WILL BE MONITORED AND A WATCH IS POSSIBLE IF AN INCREASE IN
STORM COVERAGE AND/OR INTENSITY OCCURS.

DISCUSSION...RECENT TSTM DEVELOPMENT HAS OCCURRED NEAR A
QUASISTATIONARY FRONT SITUATED ACROSS SRN AR/NERN LA. DEVELOPMENT
NEAR THIS BOUNDARY MAY BE TIED TO THE PASSAGE OF A WEAK SMALL-SCALE
SHORTWAVE TROUGH/MCV ALOFT. COOLER MID-LEVEL TEMPERATURES NEAR THIS
IMPULSE HAVE LIKELY CONTRIBUTED TO AN INCREASE IN MID-LEVEL LAPSE
RATES AND RESULTANT INSTABILITY. HOWEVER...OVERALL THERMODYNAMIC
PROFILE APPEARS CHARACTERIZED BY MODEST TO STRONG INHIBITION BASED
ON LATEST RAP SOUNDING DATA. SHORT-TERM MODEL DATA ADDS TO
UNCERTAINTY WITH REGARD TO STORM EVOLUTION ACROSS THE REGION WITH
THE LATEST NAM SUGGESTING AN INCREASE IN CONVECTION THROUGH THE
EVENING BUT LATEST HRRR INDICATING LITTLE ADDITIONAL DEVELOPMENT. IF
CONVECTION CAN INCREASE AND OVERCOME INHIBITION INDICATED IN
FORECAST SOUNDINGS THERE IS SUFFICIENT LOW LEVEL SPEED AND
DIRECTIONAL SHEAR TO CONTRIBUTE TO MODEST UPDRAFT ROTATION WITH SOME
CHANCE FOR HAIL AND EVEN A BRIEF/WEAK TORNADO. IF ACTIVITY CONTINUES
TO INCREASE IN COVERAGE AND/OR INTENSITY A WATCH MAY BE NEEDED.

..CARBIN/WEISS.. 05/17/2013

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

ATTN...WFO...JAN...LZK...SHV...

LAT...LON 32059232 32549318 32959373 33479373 33819343 33929235
33849186 33599145 32879053 32289021 31649071 31569136
32059232

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