SPC Mesoscale Discussions

SPC MESOSCALE DISCUSSION #0989 FOR ERN NY ACROSS MUCH OF SRN AND CENTRAL
NEW ENGLAND 

CONCERNING...SEVERE THUNDERSTORM POTENTIAL... 

VALID 021749Z - 022000Z 

WW MAY BE REQUIRED IN THE NEXT HOUR OR SO. 

SURFACE WINDS CONTINUE TO VEER ACROSS MUCH OF ERN NY..CT..WRN MA EARLY
THIS AFTERNOON...WITH SWLY FLOW AIDING IN DESTABILIZATION ACROSS THIS
REGION.  WARM FRONT/COSTAL BOUNDARY APPEARS TO HAVE LIFTED RAPIDLY NWD
INTO SRN ME/CENTRAL NH TO FAR NRN NY/NWRN VT
...WITH LOWER 60F SURFACE DEW POINTS ADVECTING NNEWD BEHIND THIS
BOUNDARY.  WITH PERSISTENT HEIGHT FALLS AND INCREASING WSWLY FLOW
THROUGH THE BOUNDARY LAYER...FRONT SHOULD CONTINUE LIFTING NNEWD ACROSS
THE REMAINDER OF NEW ENGLAND THROUGH THE AFTERNOON. 

MOST-UNSTABLE CAPES TO 3500 J/KG HAVE DEVELOPED INTO ERN NY...WITH 500
J/KG MUCAPES NOW INTO WRN NEW ENGLAND.  EXPECT CAPES IN THE 1000-1500
J/KG TO DEVELOP NEW INTO CENTRAL NEW ENGLAND OVER THE NEXT COUPLE OF
HOURS.  THEREFORE...AS INCREASING UVV/S SPREAD EWD AND CONVECTION
INCREASES OVER CENTRAL NY...SEVERE THREAT APPEARS TO BE SPREADING INTO
THIS AREA. 

..EVANS.. 06/02/00



SPC MESOSCALE DISCUSSION #0990 FOR CENTRAL/WRN NY AND PA..CENTRAL/ SRN
OH CONCERNING...SEVERE THUNDERSTORM POTENTIAL...REF WW/S 406 AND 407 

VALID 021837Z - 022100Z 

LATEST INSTABILITY ANALYSIS INDICATES CAPES IN THE 2000-3000 J/KG RANGE
ACROSS THE OHIO RIVER VALLEY INTO CENTRAL NY AND MUCH OF PA 
...WITH TEMPERATURES NOW IN THE LOWER 90S OVER A FEW AREAS OF CENTRAL
PA.  VWPS OVER THE REGION CONTINUE TO INDICATE STRONG WLY FLOW AND NEAR
UNIDIRECTIONAL WIND PROFILES...SUPPORTING THE POTENTIAL FOR BOW ECHOES.
LINE OF STORMS HAS INCREASED ACROSS WRN NY AND NWRN PA INTO CENTRAL OH
ALONG COLD FRONT...WHICH WILL CONTINUE SHIFTING ESEWD INTO CENTRAL NY/PA
AND TOWARDS THE OH RIVER VALLEY OVER THE NEXT FEW HOURS. 18Z SOUNDINGS
FROM PIT AND ILN INDICATE WARM SECTOR IS FAVORABLE FOR STRONG
DOWNDRAFTS... SUPPORTING PRIMARY THREAT OF DAMAGING WINDS. 

VWP/S FROM PA AND NY INDICATE VERY STRONG 0-3 KM SHEAR...WITH 0-3 KM
HELICITIES FROM 100-200 M2/S2 FROM SSEWD MOVING STORMS.  THIS WOULD
SUPPORT PERSISTENT SUPERCELLS AND POSSIBLY A TORNADO OR TWO FROM RIGHT
MOVING STORM SPLITS ACROSS ERN OH AND INTO NY AND PA...ESPECIALLY FROM
ISOLATED CELLS DEVELOPING AHEAD OF PRIMARY LINE ALONG COLD FRONT. 

..EVANS.. 06/02/00