MESO: Mesoscale Discussion 1903

ACUS11 KWNS 212333
SWOMCD
SPC MCD 212332
NCZ000-VAZ000-MDZ000-DCZ000-SCZ000-220200-

MESOSCALE DISCUSSION 1903
NWS STORM PREDICTION CENTER NORMAN OK
0632 PM CDT SAT SEP 21 2013

AREAS AFFECTED...SC...CNTRL NC AND VA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 212332Z - 220200Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...A FEW LOW TOPPED THUNDERSTORMS COULD PRODUCE LOCALLY
STRONG WIND GUSTS THIS EVENING. IN ADDITION...AN ISOLATED BRIEF WEAK
TORNADO CANNOT BE RULED OUT. HOWEVER...OVERALL THREAT AND COVERAGE
IS EXPECTED TO BE TOO LOW FOR A WATCH.

DISCUSSION...SURFACE ANALYSIS SHOWS A LOW OVER NWRN SC WITH SFC
TROUGH EXTENDING NEWD ACROSS CNTRL VA. WEAK PRESSURE FALLS WERE
NOTED NEAR THE SFC LOW...AND ACROSS VA WHERE A N-S ORIENTED LINE OF
CONVECTION HAS FORMED...PRESUMABLY ALONG THE LEADING EDGE OF WARM
ADVECTION ABOVE THE SURFACE.

INSTABILITY ACROSS THE ENTIRE REGION CONTINUES TO BE WEAK...WITH
ECHO TOPS GENERALLY IN THE 15-20K FT RANGE. ALMOST NO LIGHTNING WAS
OCCURRING AS OF 2330Z. HOWEVER...FORCING ALONG VARIOUS WEAK FRONTAL
WAVES FROM NWRN SC INTO VA HAVE RESULTED IN A FEW AREAS OF ENHANCED
REFLECTIVITY AND TRANSIENT WEAK SHEAR COUPLETS. GIVEN THE RELATIVELY
COOL SURFACE AIR MASS...AN UPWARD TREND IN INTENSITY IS NOT
ANTICIPATED...BUT A FEW STRONG WIND GUSTS WILL REMAIN POSSIBLE...OR
EVEN A WEAK BRIEF TORNADO EITHER WITH ACTIVITY NEAR THE FRONT OR
WITH THE PRE-FRONTAL STORMS OVER ERN VA WHERE LOW LEVEL SHEAR IS
STRONGEST.

..JEWELL/MEAD.. 09/21/2013

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

ATTN...WFO...AKQ...MHX...LWX...RAH...ILM...RNK...CAE...GSP...

LAT...LON 34148227 34478263 34888247 36158041 37317906 38927783
39027742 39017697 38837673 38337643 37297606 36517615
36077653 35627696 34887796 34307937 34038083 34148227

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