Tornado Watch 646

Issued

Sep 18, 2012, 3:38 PM EDT (19:38 UTC)

Expired

Sep 19, 2012, 12:00 AM EDT

In force

8 hr

Issued by

the Storm Prediction Center

Largest hail expected

0.5 in

Strongest gust expected

60 kt

The Albany radar (KENX), 28 km from the middle of the area, began a volume at 19:41 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

40%

One or more EF2 to EF5 tornadoes

20%

Ten or more severe wind reports

40%

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

70%

• Mesoscale Discussion 1962Sep 18, 12:57 PM EDT
• Mesoscale Discussion 1966Sep 18, 2:10 PM EDT
• Mesoscale Discussion 1967Sep 18, 3:26 PM EDT
• Mesoscale Discussion 1970Sep 18, 4:21 PM EDT
• Mesoscale Discussion 1974Sep 18, 7:42 PM EDT
• Mesoscale Discussion 1975Sep 18, 10:00 PM EDT

945 
WWUS20 KWNS 181938
SEL6
SPC WW 181938
CTZ000-MAZ000-NYZ000-CWZ000-190300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 646
NWS STORM PREDICTION CENTER NORMAN OK
340 PM EDT TUE SEP 18 2012

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

       WESTERN CONNECTICUT
       WESTERN MASSACHUSETTS
       EASTERN NEW YORK
       COASTAL WATERS

EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 340 PM UNTIL
1100 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 45 STATUTE
MILES EAST AND WEST OF A LINE FROM 30 MILES NORTH NORTHWEST OF
GLENS FALLS NEW YORK TO 10 MILES SOUTH SOUTHEAST OF POUGHKEEPSIE
NEW YORK.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).

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...WW
643...WW 644...WW 645...

DISCUSSION...A STRONGLY FORCED CONVECTIVE BAND OVER CNTRL NY SHOULD
CONTINUE TO STRENGTHEN AS IT PROGRESSES EWD THROUGH THE HUDSON
VALLEY THIS EVENING.  AMBIENT ENVIRONMENT IS CHARACTERIZED BY VERY
WEAK INSTABILITY...BUT INTENSE VERTICAL SHEAR AND FORCING FOR
ASCENT.  AND WHILE DAMAGING WINDS WILL BE THE PRIMARY SEVERE WEATHER
HAZARD WITH THIS CONVECTIVE BAND...TORNADOES WILL BE POSSIBLE OWING
TO THE STRONG LOW-LEVEL SHEAR AND LOW LCL/MOIST BOUNDARY LAYER.

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
300. MEAN STORM MOTION VECTOR 23045.


...MEAD

Tornado Watches in New York, 2012Tornado Watches in Connecticut, 2012Tornado Watches in Massachusetts, 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.