URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 263
NWS STORM PREDICTION CENTER NORMAN OK
440 PM EDT SUN MAY 23 2004
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
WESTERN CONNECTICUT
NORTHERN NEW JERSEY
SOUTHERN NEW YORK
NORTHEAST PENNSYLVANIA
LAKE ONTARIO
LAKE ERIE
COASTAL WATERS
EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 440 PM UNTIL 1000 PM EDT.
HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 55 STATUTE MILES NORTH AND SOUTH OF A LINE FROM 45 MILES WEST SOUTHWEST OF ELMIRA NEW YORK TO 40 MILES SOUTHEAST OF POUGHKEEPSIE NEW YORK.
REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES.
OTHER WATCH INFORMATION...CONTINUE...WW 259...WW 261...WW 262...
DISCUSSION...SCATTERED STRONG/SEVERE STORMS ARE FORECAST TO CONTINUE ALONG SURFACE WARM FRONT ALONG THE PA/NY BORDER. MODERATELY UNSTABLE AIRMASS AND SUFFICIENT DEEP LAYER SHEAR WILL SUPPORT A RISK
OF LARGE HAIL AND DAMAGING WINDS IN STRONGER CELLS.
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM MOTION VECTOR 28030.
...HART
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Have my concerns about the validity of the SW portion of WW 263, where deep layer vertical shear per 21z mesoanalysis in the lowest 6 KM especially) is < 30 KT over much of the PA portion of WW 263.
the best vertical shear through a deep layer remains in the vicinity of the warm front along and north of the NY/PA border, with the best instability south of there. Notice however, MOST of the thunderstorms which have gone severe THUS FAR this afternoon were across the lower hudson Valley and western catskills where the combination of the northern extent of the best instability and southern extent of the best deep layer shear coincide. basically right INVOF of the warm front.
Although...over much of PA (and in spite of the weak deep layer shear), Mid level lapse rates 7.0-8.0 DEG C/km and SB CAPE of between 2000 and 2500 J/kg over much of the PA portion of the watch should support pulse type severe thunderstorms capible of producing wind damage and perhaps some marginally severe hail.
