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000
ACUS11 KWNS 272210
SWOMCD
SPC MCD 272209
NYZ000-NJZ000-PAZ000-MDZ000-WVZ000-272315-

MESOSCALE DISCUSSION 1489
NWS STORM PREDICTION CENTER NORMAN OK
0509 PM CDT SUN JUL 27 2014

AREAS AFFECTED...PARTS OF SRN NEW YORK...CNTRL/ERN PA...PARTS OF
ADJACENT MARYLAND AND NEW JERSEY

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 272209Z - 272315Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...CONVECTION IS LIKELY TO INCREASE IN COVERAGE WHILE
SPREADING EAST NORTHEASTWARD ACROSS THE REGION INTO THE 00-03Z TIME
FRAME.  THIS COULD BE ACCOMPANIED BY AN INCREASING SEVERE WEATHER
RISK...MAINLY IN THE FORM OF STRONG WIND GUSTS...BUT IT REMAINS
UNCERTAIN HOW ORGANIZED THIS THREAT WILL BECOME.

DISCUSSION...MODIFICATION OF THE LOWER/MID TROPOSPHERIC ENVIRONMENT
IN THE WAKE OF EARLY DAY DRYING...NORTHEAST OF THE UPPER OHIO VALLEY
INTO AREAS EAST OF THE LOWER GREAT LAKES...IS SLOWLY UNDERWAY.  THE
LEADING EDGE OF THE BETTER MOISTURE RETURN...AS EVIDENT IN THE
PRECIPITABLE WATER FIELDS...GENERALLY COINCIDES WITH AN AREA OF
INCREASING THUNDERSTORM ACTIVITY EXTENDING ALONG AN AXIS EAST
NORTHEAST OF CLEVELAND OH INTO AREAS WEST OF LANCASTER PA.
LOW-LEVEL FOCUS FOR CONVECTIVE DEVELOPMENT APPEARS
WEAK/UNCERTAIN...BUT ACTIVITY TO THE LEE OF LAKE ERIE IS LIKELY
BEING AIDED BY STRENGTHENING DIVERGENCE IN THE LEFT EXIT REGION OF A
SEASONABLY STRONG HIGH LEVEL JET NOSING THROUGH THE OHIO VALLEY.
MODELS SUGGEST THIS UPPER FORCING WILL CONTINUE TO INCREASE ALONG AN
AXIS ROUGHLY EAST SOUTHEASTWARD ALONG THE NEW YORK/PENNSYLVANIA
BORDER THROUGH LATE EVENING.  THIS IS GENERALLY NORTH OF THE
STRONGER MID-LEVEL FLOW AND THE BETTER SHEAR PROFILES FOR ORGANIZED
SEVERE STORM DEVELOPMENT.  BUT AS MODERATELY LARGE CAPE DEVELOPS
EAST NORTHEASTWARD...IT DOES NOT APPEAR OUT OF THE QUESTION THAT
INCREASING STORM DEVELOPMENT COULD BE ACCOMPANIED BY AT LEAST SOME
INCREASE IN RISK FOR POTENTIALLY DAMAGING WIND GUSTS.

..KERR/EDWARDS.. 07/27/2014

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

ATTN...WFO...PHI...BGM...BUF...CTP...LWX...PBZ...

LAT...LON   42297931 42527693 42287531 41407474 40157543 39547680
            39687868 41147921 42297931

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