

097 

WWUS20 KWNS 211921

SEL7

SPC WW 211921

MEZ000-NHZ000-CWZ000-220200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 797

NWS STORM PREDICTION CENTER NORMAN OK

320 PM EDT SUN AUG 21 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHERN AND WESTERN MAINE

       NEW HAMPSHIRE

       COASTAL WATERS



EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 320 PM UNTIL

1000 PM EDT.



HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60

STATUTE MILES EAST AND WEST OF A LINE FROM 195 MILES NORTH

NORTHEAST OF BERLIN NEW HAMPSHIRE TO 20 MILES EAST OF CONCORD NEW

HAMPSHIRE.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).



REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE

FAVORABLE FOR 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. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY

DO PRODUCE TORNADOES.



OTHER WATCH INFORMATION...CONTINUE...WW 794...WW 795...WW 796...



DISCUSSION...PRE-FRONTAL BAND OF THUNDERSTORMS WILL CONTINUE

EWD/NEWD ACROSS NY INTO W/SW MAINE THIS AFTERNOON...WHILE ADDITIONAL

ISOLATED STORMS CONTINUE TO FORM AHEAD OF THIS BAND.  STRONG SURFACE

HEATING THROUGH MUCH OF THE AFTERNOON HAS RESULTED IN MODERATE

INSTABILITY ACROSS MAINE...WHILE VERTICAL SHEAR WILL SLOWLY INCREASE

WITH THE APPROACH OF THE MIDLEVEL TROUGH FROM THE W.  THE

ENVIRONMENT WILL BE SUFFICIENT FOR A FEW STORMS WITH DAMAGING WINDS

AND LARGE HAIL FOR THE NEXT SEVERAL HOURS.  ALSO...THERE WILL BE

SOME POTENTIAL FOR FRONTAL CONVECTION TO MOVE INTO THE WATCH AREA

FROM THE W LATER THIS EVENING.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM

MOTION VECTOR 25025.





...THOMPSON

