MESO: Mesoscale Discussion 0839

ACUS11 KWNS 282001
SWOMCD
SPC MCD 282001
MDZ000-VAZ000-DCZ000-WVZ000-282230-

MESOSCALE DISCUSSION 0839
NWS STORM PREDICTION CENTER NORMAN OK
0301 PM CDT TUE MAY 28 2013

AREAS AFFECTED...NRN VA...MD INCLUDING THE DC-BALTIMORE METRO AREAS
TO PARTS ERN SHORE OF MD

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 282001Z - 282230Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...POTENTIAL EXISTS FOR ISOLATED TO SCATTERED TSTM
DEVELOPMENT ACROSS NRN VA INTO MD INCLUDING THE DC-BALTIMORE METRO
AREAS TO PARTS OF MD/S EASTERN SHORE THIS AFTERNOON INTO THE EARLY
EVENING. MARGINAL INSTABILITY AND WEAK SHEAR WILL LIMIT THE
COVERAGE OF STRONGER-SVR STORMS...AND THUS PRECLUDES 1/ AN UPGRADE
TO A CATEGORICAL SLIGHT RISK AND 2/ THE NEED FOR SVR WEATHER WATCH.

DISCUSSION...EARLY AFTERNOON SURFACE ANALYSIS SHOWED A WARM FRONT
EXTENDING N-S ACROSS FAR ERN OH INTO FAR SWRN PA...AND THEN DRAPED
ESEWD THROUGH THE WV PANHANDLE /N OF PETERSBURG/ TO FAR NRN VA AND
BETWEEN KIAD-KBWI. DESPITE STRONG SURFACE HEATING S OF THE WARM
FRONT RESULTING IN CONVECTIVE TEMPERATURES BEING BREACHED PER
MODIFIED 12Z SOUNDINGS AT IAD/RNK...WEAK MIDLEVEL LAPSE RATES ARE
TEMPERING THE DEGREE OF DESTABILIZATION /MLCAPE 500-1000 J PER KG/.
REGIONAL RADAR IMAGERY SHOWED A FEW STORMS HAD DEVELOPED WITHIN A
LOW LEVEL CONVERGENCE ZONE AND OFF THE HIGHER TERRAIN IN WRN
VA...WHILE A SHORT BROKEN LINE OF STORMS WAS MOVING ENEWD THROUGH
SWRN PA. THIS LATTER ACTIVITY WAS LOCATED WITH FORCING FOR ASCENT
ATTENDANT TO A PROGRESSIVE MIDLEVEL MCV.

SEVERAL OF THE HIGH RES MODELS SUGGESTED GREATER STORM COVERAGE WITH
ACTIVITY EVENTUALLY MOVING ESEWD THROUGH NERN VA/MD TO THE MD ERN
SHORE BY EARLY EVENING. HOWEVER...AFOREMENTIONED OBSERVATIONAL
TRENDS WITH LIMITED CONVECTIVE COVERAGE THUS FAR AND WEAK LARGE
SCALE FORCING GIVEN BACKGROUND HEIGHT RISES WOULD SUGGEST ANY
STRONGER STORMS SHOULD REMAIN GENERALLY ISOLATED TO SCATTERED AT
BEST. IN ADDITION...WEAK BULK SHEAR WILL LIMIT STORM ORGANIZATION
AND THE OVERALL POTENTIAL FOR A GREATER SVR WEATHER THREAT. LOCALLY
STRONG WIND GUSTS ARE POSSIBLE WITH THE DIURNAL TSTMS...GIVEN STEEP
LOW LEVEL LAPSE RATES.

..PETERS/MEAD.. 05/28/2013

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

ATTN...WFO...PHI...AKQ...LWX...RNK...

LAT...LON 37847883 39087791 39407743 39337658 38997579 38347580
37917611 37377684 37367774 37377864 37437886 37847883

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