MESO: Mesoscale Discussion 1004

ACUS11 KWNS 011704
SWOMCD
SPC MCD 011703
NCZ000-MDZ000-VAZ000-PAZ000-DCZ000-WVZ000-011830-

MESOSCALE DISCUSSION 1004
NWS STORM PREDICTION CENTER NORMAN OK
1203 PM CDT FRI JUN 01 2012

AREAS AFFECTED...NC...VA...WV...MD...DC...PA

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY

VALID 011703Z - 011830Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...THUNDERSTORMS WILL INCREASE THROUGH THE AFTERNOON IN A
VERY MOIST AND INCREASINGLY UNSTABLE AIRMASS FROM NC NWD ACROSS
VA...SRN PA...WV PNHDL...AND MD/DC AREA. RECENT TRENDS SUGGEST THAT
ISOLATED STORMS WILL FIRST POSE A THREAT FOR ISOLATED SEVERE WEATHER
IN THE FORM OF HAIL/WIND OVER PARTS OF NERN NC AND SERN VA WHERE
INSTABILITY IS GREATEST BUT SHEAR AND FORCING WILL REMAIN LIMITED
FOR A TIME. ADDITIONAL SEVERE STORMS ARE LIKELY AS A FORCED SQUALL
LINE DEVELOPS EAST OF THE APPALACHIANS LATER THIS AFTERNOON. DEEP
SHEAR AND TORNADO POTENTIAL MAY INCREASE ACROSS THE ENTIRE REGION
FROM LATE AFTERNOON INTO EVENING AND ONE OR MORE TORNADO WATCHES
WILL LIKELY BE ISSUED OVER THE NEXT 1-2 HOURS.

DISCUSSION...STRONG FORCED ASCENT WITH A LARGE SCALE TROUGH WAS
LIKELY RESULTING IN AN INCREASE IN LOW-TOPPED CONVECTION ALONG A
COLD FRONT NOW SITUATED FROM ERN OH SWD ACROSS WV...EXTREME SWRN VA
AND ERN TN. EXPECT THAT THIS CONVECTION WILL CROSS THE SPINE OF THE
APPALACHIANS OVER THE NEXT 2 HOURS. AS THIS FORCING BEGINS TO
INTERACT WITH GREATER INSTABILITY EAST OF THE MOUNTAINS...MORE
VIGOROUS STORM DEVELOPMENT IN THE FORM OF BOWING/LEWPING SEGMENTS
CAN BE EXPECTED. A WEAK FRONTAL WAVE MAY ALSO TAKE FORM WITH TIME
COINCIDENT WITH AN INCREASE IN STORMS ALONG A WARM FRONT EXTENDING
ACROSS SRN PA AND INTO THE DELMARVA REGION. IN ADDITION TO WIND
DAMAGE THREAT WITH STORMS ALONG THE ADVANCING FRONT...AN ENHANCED
BUT FOCUSED TORNADO THREAT MAY EVOLVE NEAR THE FRONTAL WAVE AND WARM
FRONT. ONE TORNADO WATCH WILL LIKELY BE NEEDED FROM SRN PA ACROSS
WRN VA WITHIN THE NEXT HOUR OR SO.

ANOTHER WATCH WILL LIKELY BE NEEDED FROM THE ONGOING STORMS OVER NRN
NC NWD ACROSS THE VA TIDEWATER AREA. STORMS IN THIS AREA ARE
DEVELOPING WITH HEATING OF THE DAY AND PERHAPS THE LARGER SCALE
ASCENT DEVELOPING EAST WITH THE TROUGH. WHILE INSTABILITY IS GREATER
IN THIS CORRIDOR...DEEP SHEAR AND FORCING ARE LIKELY MORE MARGINAL
TO SUPPORT A MORE WIDESPREAD IMMEDIATE THREAT OF SEVERE TSTMS
WIND/TORNADOES. NONETHELESS...SHEAR WILL LIKELY INCREASE
SUFFICIENTLY WITH TIME ACROSS THIS AREA TO WARRANT A TORNADO WATCH
AND THIS WATCH WILL LIKELY BE COORDINATED SHORTLY.

..CARBIN.. 06/01/2012

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

ATTN...WFO...PHI...AKQ...MHX...CTP...LWX...RAH...RNK...PBZ...
RLX...

LAT...LON 38408025 40257988 40477934 40297812 39657645 39017601
37387611 36877609 35757572 35507692 35827806 36427895
36447972 36738043 37068060 37358072 38408025

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