

718 

WWUS20 KWNS 050552

SEL4

SPC WW 050552

FLZ000-CWZ000-051400-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 794

NWS STORM PREDICTION CENTER NORMAN OK

1250 AM EST SAT DEC 5 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       SOUTHERN FLORIDA AND THE FLORIDA KEYS

       COASTAL WATERS



EFFECTIVE THIS SATURDAY MORNING FROM 1250 AM UNTIL 900 AM EST.



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 50 STATUTE

MILES EITHER SIDE OF A LINE FROM 30 MILES NORTHEAST OF WEST PALM

BEACH FLORIDA TO 45 MILES WEST OF MARATHON FLORIDA.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU4).



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...TSTMS THAT HAVE PERSISTED SINCE EARLY FRIDAY EVE OFF

THE SW FL CST HAVE SOMEWHAT INCREASED IN STRENGTH AND ORGANIZATION

IN THE PAST HOUR.  THIS TREND MAY BE IN RESPONSE TO INCREASING LARGE

SCALE ASCENT ASSOCIATED WITH SHORT WAVE TROUGH NOW OVER THE N CNTRL

GULF OF MEXICO...AND DOWNSTREAM DEVELOPMENT OF JET ENTRANCE REGION

ACROSS FL AND THE WRN ATLANTIC.  AT ANY RATE...COMBINATION OF VERY

RICH MOISTURE...MODERATE SHEAR...AND LOW LVL ASCENT INVOF EXISTING

OUTFLOW BOUNDARIES AND SYNOPTIC WARM/STNRY FRONT SUGGEST THE

POTENTIAL FOR A FEW SUSTAINED STORMS AND/OR EMBEDDED SUPERCELLS WITH

SMALL BOWS.  THE STORMS MAY PRODUCE WET MICROBURSTS AND POSSIBLY A

COUPLE TORNADOES THROUGH LATER THIS MORNING.



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

500. MEAN STORM MOTION VECTOR 24030.





...CORFIDI

