Watch out W.NY, W.PA, and NE OH!

[wx247]

MESOSCALE DISCUSSION 0406
NWS STORM PREDICTION CENTER NORMAN OK
1148 AM CDT WED APR 21 2004

AREAS AFFECTED...CENTRAL/ERN OH...WRN/NWRN PA...AND WRN NY

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 211648Z - 211915Z

INCREASING COVERAGE OF THUNDERSTORMS EXPECTED THROUGH MID-AFTERNOON
FROM CENTRAL OH NEWD INTO FAR WRN NY. DAMAGING WINDS ARE POSSIBLE
WITH THIS ACTIVITY. AREA WILL BE MONITORED FOR A POSSIBLE SEVERE
THUNDERSTORM WATCH DURING THE NEXT 1-3 HOURS.

AT 16Z...A BROKEN LINE OF SHOWERS AND DEVELOPING THUNDERSTORMS
EXTENDS FROM ERN LAKE ERIE SWWD INTO COLUMBUS OH VICINITY. THETA-E
RIDGE EXISTS JUST EAST OF THIS LINE...WHERE SURFACE TEMPERATURES
HAVE WARMED INTO THE 70S FROM ERN OH NEWD INTO WRN NY. WHILE SURFACE
DEWPOINTS IN THE 50S WILL YIELD ONLY MARGINAL SBCAPE / AROUND 1000
J/KG/ BY MID-AFTERNOON...40-50 KT FLOW AT 1-2 KM PER CLE AND BUF VAD
PROFILES...AND SFC-6KM SHEAR OF 50 KT...SUGGESTS THE POSSIBILITY OF
DAMAGING SURFACE WINDS ASSOCIATED WITH DOWNWARD MOMENTUM TRANSPORT
IN CONVECTIVE DOWNDRAFTS. THIS WILL LIKELY REPRESENT THE PRIMARY
SEVERE WEATHER THREAT. INDIVIDUAL CELLS SHOULD MOVE RAPIDLY NEWD AT
40-45 KT.

GIVEN FAVORABLE DEEP-LAYER SHEAR PROFILES...AN ISOLATED SUPERCELL OR
TWO IS ALSO POSSIBLE DESPITE LOW CAPE. THREAT FOR SEVERE HAIL WILL
BE GREATEST WITH THE STRONGER AND LONGER-LIVED UPDRAFTS OF ROTATING
STORMS. WBZ HEIGHTS AROUND 8 KFT ARE ALSO FAVORABLE FOR HAIL GIVEN
STRONG UPDRAFTS.