MESO: Mesoscale Discussion 0816

ACUS11 KWNS 151809
SWOMCD
SPC MCD 151808
MDZ000-VAZ000-NCZ000-DCZ000-WVZ000-151915-

MESOSCALE DISCUSSION 0816
NWS STORM PREDICTION CENTER NORMAN OK
0108 PM CDT TUE MAY 15 2012

AREAS AFFECTED...WRN NC / WRN-CNTRL-NRN VA / PARTS OF MD

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 151808Z - 151915Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...SCTD TSTMS ARE EXPECTED TO DEVELOP 18-21Z. THE STRONGER
STORMS WILL POSE AN ISOLD DMGG WIND/LARGE HAIL RISK.

DISCUSSION...SURFACE MESOANALYSIS PLACES A WEAK SURFACE TROUGH
EXTENDING NEWD FROM THE LEE OF THE SRN APPALACHIANS NEWD INTO WRN
VA. THE INFLUENCE OF WEAK SHORTWAVE RIDGING ALOFT WILL ABATE THIS
AFTERNOON AS A WEAK SHORTWAVE TROUGH OVER THE TN VALLEY MOVES NEWD
WITHIN A BROAD CYCLONIC FLOW REGIME CENTERED FARTHER W OVER THE
LOWER MS RIVER VALLEY. ALTHOUGH MID-LEVEL LAPSE RATES ARE NOT
PARTICULARLY STEEP /6.5 DEG C PER KM --REF 12Z GSO RAOB/...FURTHER
HEATING WILL ALLOW TEMPS TO CONTINUE TO WARM THROUGH THE 70S AND
INTO THE 80S AND LEAD TO MLCAPE ON THE ORDER OF 1000-1500 J/KG. AS
SUCH...POCKETS OF SUNSHINE WILL INCREASE 0-2 KM LAPSE RATES AND
BECOME MORE CONDUCIVE FOR INTERMITTENT BOUTS OF STRONGER DOWNDRAFT
PENETRATION IN THE FORM OF LOCALIZED STRONG/MARGINALLY SEVERE WIND
GUSTS.

THE LAST FEW RUNS OF THE HRRR AND OTHER CONVECTION-ALLOWING MODEL
GUIDANCE SHOW SCTD STORMS DEVELOPING IN THE 18-21Z
PERIOD...CONCENTRATED INVOF THE MTNS OVER WRN NC NEWD INTO THE VA
PIEDMONT. THE MULTICELLULAR CHARACTER OF THESE STORMS SUGGEST AT
LEAST SOME LARGE HAIL RISK WILL DEVELOP WITH THE STRONGER
UPDRAFTS...BEFORE APPRECIABLE CONVECTIVE OVERTURNING/LOSS OF HEATING
TOWARDS EVENING LESSENS THIS RISK.

..SMITH/HART.. 05/15/2012

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

ATTN...WFO...PHI...AKQ...LWX...RAH...RNK...GSP...

LAT...LON 35718220 36248175 39267789 39177670 38487601 36667625
35608063 35498170 35718220

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