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561 

WWUS20 KWNS 201906

SEL6

SPC WW 201906

DEZ000-MDZ000-VAZ000-CWZ000-210000-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 486

NWS STORM PREDICTION CENTER NORMAN OK

305 PM EDT SAT JUN 20 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       DELAWARE

       EASTERN AND SOUTHERN MARYLAND

       SOUTHEAST VIRGINIA

       COASTAL WATERS



EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 305 PM UNTIL

800 PM EDT.



TORNADOES...HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 70 STATUTE

MILES EITHER SIDE OF A LINE FROM 60 MILES SOUTH OF PATUXENT RIVER

MARYLAND TO 40 MILES NORTH NORTHWEST OF DOVER DELAWARE.  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.



DISCUSSION...WIDELY SCATTERED THUNDERSTORMS ARE DEVELOPING FROM

EXTREME SERN PA SWD INTO EAST CENTRAL VA IN ASSOCIATION WITH STRONG

DYNAMIC FORCING FOR LARGE SCALE ASCENT ALONG A SHORT WAVE

TROUGH/VORTICITY MAX MOVING EWD ACROSS THE MID ATLANTIC REGION.  THE

AIR MASS HAS WARMED SUBSTANTIALLY OVER THE AREA TO THE IMMEDIATE

WEST OF A WARM FRONT AND IN THE WAKE OF EARLIER CONVECTION...WITH

TEMPERATURES IN THE 80S AND DEW POINTS REMAINING IN THE LOW 70S.

WIND PROFILES SUBSTANTIALLY WITH HEIGHT AND 40-50 KT WNWLY FLOW

ABOVE 2-3 KM IS CONTRIBUTING TO STRONG DEEP LAYER SHEAR AS WELL AS

150-300 MS/S2 LOW-LEVEL HELICITY.  THE ENVIRONMENT APPEARS FAVORABLE

FOR SUPERCELL STORMS TO DEVELOP WITH THREAT FOR ISOLATED TORNADOES

AS WELL AS LARGE HAIL AND DAMAGING WIND GUSTS.



AVIATION...TORNADOES AND 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 28025.





...WEISS

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