Mesoscale Discussion 649

Issued

May 11, 2004, 11:53 AM EDT (15:53 UTC)

Expired

May 11, 2004, 2:30 PM EDT

In force

3 hr

Issued by

the Storm Prediction Center

The Brookhaven radar (KOKX), 61 km from the middle of the area, began a volume at 15:56 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

815 
ACUS11 KWNS 111553
SWOMCD
SPC MCD 111553 
RIZ000-CTZ000-NYZ000-NJZ000-PAZ000-111830-

MESOSCALE DISCUSSION 0649
NWS STORM PREDICTION CENTER NORMAN OK
1053 AM CDT TUE MAY 11 2004

AREAS AFFECTED...ERN PA...NRN/CENTRAL NJ...SERN NY...CT...AND WRN RI

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 111553Z - 111830Z

THUNDERSTORM DEVELOPMENT EXPECTED ALONG COLD FRONT DURING NEXT 1-3
HOURS ACROSS ERN PA/NRN NJ/SERN NY/CT AREA. ISOLATED DAMAGING WINDS
AND/OR HAIL IS ANTICIPATED ACROSS THE DISCUSSION AREA WITH STRONGER
CELLS.

AT 1530Z...STRONG DRYING IS NOTED ON WV IMAGERY ACROSS NRN NEW
ENGLAND AS SHORTWAVE TROUGH MOVES EWD TOWARD NOVA SCOTIA. ASSOCIATED
SURFACE COLD FRONT TRAILS WSWWD ACROSS WRN MA INTO THE CATSKILLS AND
ALONG THE NRN PA/SRN NY BORDER. THIS BOUNDARY WILL CONTINUE TO PUSH
SEWD TOWARD ERN PA/NRN NJ/NYC METRO DURING THE NEXT FEW HOURS.

AIR MASS SOUTH OF THE FRONT IS ALREADY BECOMING MODERATELY
UNSTABLE...WITH LOW TO MID 60S DEWPOINTS CONTRIBUTING TO 100MB
MLCAPE VALUES OF 1000-1500 J/KG. FURTHER SURFACE HEATING SHOULD
INITIATE THUNDERSTORMS IN A WSW-ENE ORIENTED FASHION ALONG THE
FRONT. SOME QUESTION REMAINS REGARDING HOW INTENSE STORMS WILL BE. 
DEEP-LAYER WLY FLOW IS PROGGED TO WEAKEN AS SHORTWAVE TROUGH MOVES
AWAY. THE 12Z ETA DROPS SFC-6KM SHEAR FROM 20KT TO 10KT OR SO ACROSS
THE REGION BY 21Z. HOWEVER... 850-500MB LAPSE RATES AT OKX AND CHH
WERE AROUND 7 C/KM THIS MORNING...SUGGESTING THE POTENTIAL FOR
STRONG UPDRAFTS. STORMS WILL LIKELY EXHIBIT PULSE CHARACTERISTICS
WITH THE THREAT OF ISOLATED DAMAGING WINDS OR MARGINALLY SEVERE HAIL
WITH A FEW OF THE STRONGER CELLS. STORMS SHOULD DEVELOP AROUND 18Z
AND MOVE SEWD 10-15 KT THROUGH ERN PA/NRN AND CENTRAL NJ/NYC
AREA/SRN CT DURING THE MID-LATE AFTERNOON. INTERACTION OF THE FRONT
WITH SEA BREEZE BOUNDARIES MAY BRIEFLY ENHANCE CONVERGENCE AND STORM
INTENSITY NEAR THE COASTLINE.

..BANACOS.. 05/11/2004

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

ATTN...WFO...BOX...OKX...ALY...PHI...BGM...CTP...

41587450 41657376 41767262 41857197 41807168 41327160
41137158 40867229 40527325 40217419 40157480 40057621
41447608

Mesoscale Discussions in New Jersey, 2004Mesoscale Discussions in New York, 2004Mesoscale Discussions in Pennsylvania, 2004Every mesoscale discussion in 2004

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.