

000 

WWUS20 KWNS 281557

SEL8

SPC WW 281557

MEZ000-290000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 558

NWS STORM PREDICTION CENTER NORMAN OK

1155 AM EDT SAT JUL 28 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       MAINE



EFFECTIVE THIS SATURDAY MORNING AND EVENING FROM 1155 AM UNTIL

800 PM EDT.



HAIL TO 2 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 145

STATUTE MILES EITHER SIDE OF A LINE FROM 45 MILES NORTHEAST OF

BANGOR MAINE TO 80 MILES NORTHWEST OF AUGUSTA MAINE.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU8).



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.



DISCUSSION...STRONG HEATING AND MOIST AIR MASS WILL CONTRIBUTE TO

CONTINUING DESTABILIZATION AHEAD OF A COMPACT SHORT WAVE TROUGH

MOVING EAST FROM NY/VT...AND SLOW MOVING FRONTAL ZONE SPREADING INTO

NRN MAINE ATTM. LIFT ASSOCIATED WITH THESE FEATURES SHOULD PROVOKE

INCREASING TSTM DEVELOPMENT WITHIN MODERATELY SHEARED ENVIRONMENT.

SUPERCELL STRUCTURES APPEAR LIKELY TO ARISE FROM MORE ROBUST

CONVECTIVE ELEMENTS THROUGH THE AFTERNOON WITH ATTENDANT THREATS OF

LARGE HAIL AND STRONG TO DAMAGING WINDS.



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

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

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

MOTION VECTOR 24020.





...CARBIN/IMY

