Tornado Watch 643

Issued

Sep 18, 2012, 12:10 PM EDT (16:10 UTC)

Expired

Sep 18, 2012, 8:56 PM EDT

In force

9 hr

Issued by

the Storm Prediction Center

Largest hail expected

0.5 in

Strongest gust expected

60 kt

The Binghamton radar (KBGM), 131 km from the middle of the area, began a volume at 16:10 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.

Two or more tornadoes

50%

One or more EF2 to EF5 tornadoes

20%

Ten or more severe wind reports

80%

One or more gusts of 65 knots or more

30%

Ten or more severe hail reports

5%

One or more hailstones of 2 inches or more

5%

Six or more combined severe hail and wind reports

90%

• Mesoscale Discussion 1957Sep 18, 8:49 AM EDT
• Mesoscale Discussion 1959Sep 18, 11:14 AM EDT
• Mesoscale Discussion 1960Sep 18, 11:19 AM EDT
• Mesoscale Discussion 1965Sep 18, 1:56 PM EDT
• Mesoscale Discussion 1970Sep 18, 4:21 PM EDT
• Mesoscale Discussion 1972Sep 18, 6:08 PM EDT
• Mesoscale Discussion 1973Sep 18, 6:15 PM EDT
• Mesoscale Discussion 1974Sep 18, 7:42 PM EDT

774 
WWUS20 KWNS 181614
SEL3
SPC WW 181614
DEZ000-MDZ000-NJZ000-NYZ000-PAZ000-CWZ000-182300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 643
NWS STORM PREDICTION CENTER NORMAN OK
1210 PM EDT TUE SEP 18 2012

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

       DELAWARE
       EASTERN MARYLAND
       NEW JERSEY
       FAR SOUTHEAST NEW YORK
       EASTERN PENNSYLVANIA
       COASTAL WATERS

EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 1210 PM UNTIL
700 PM EDT.

TORNADOES...HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 95 STATUTE
MILES EAST AND WEST OF A LINE FROM 20 MILES NORTH OF MONTICELLO
NEW YORK TO 30 MILES WEST SOUTHWEST OF PHILADELPHIA PENNSYLVANIA.
 FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU3).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND 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.

OTHER WATCH INFORMATION...CONTINUE...WW 641...WW 642...

DISCUSSION...FORCED BAND OF CONVECTION OVER CNTRL PA IS EXPECTED TO
INTENSIFY THIS AFTERNOON WITH ADDITIONAL MORE DISCRETE STORM
DEVELOPMENT POSSIBLE FARTHER E NEARER TO THE ATLANTIC COAST.
WIDESPREAD CLOUDS AND PRECIPITATION WILL LIMIT THE DEGREE OF AIR
MASS DESTABILIZATION.  HOWEVER...GIVEN THE VERY MOIST
ENVIRONMENT...SUFFICIENT INSTABILITY WILL DEVELOP TO SUPPORT TSTMS.
AS BOTH VERTICAL SHEAR AND FORCING FOR ASCENT CONTINUE TO INCREASE
THROUGH THE AFTERNOON...EXPECT A CORRESPONDING ORGANIZATION OF
STORMS INTO LEWP/BOW STRUCTURES AND POSSIBLY SUPERCELLS CAPABLE OF
TORNADOES AND DAMAGING WINDS.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
400. MEAN STORM MOTION VECTOR 23040.


...MEAD

Tornado Watches in Pennsylvania, 2012Tornado Watches in New Jersey, 2012Tornado Watches in New York, 2012Every tornado watch in 2012

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.