

000 

WWUS20 KWNS 130442

SEL8

SPC WW 130442

LAZ000-CWZ000-131200-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 18

NWS STORM PREDICTION CENTER NORMAN OK

1040 PM CST MON FEB 12 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       CENTRAL AND SOUTHEASTERN LOUISIANA

       COASTAL WATERS



EFFECTIVE THIS MONDAY NIGHT AND TUESDAY MORNING FROM 1040 PM

UNTIL 600 AM CST.



TORNADOES...HAIL TO 1 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 60 STATUTE

MILES EITHER SIDE OF A LINE FROM 60 MILES WEST NORTHWEST OF

LAFAYETTE LOUISIANA TO 25 MILES EAST SOUTHEAST OF NEW ORLEANS

LOUISIANA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).



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...THIS TORNADO WATCH REPLACES TORNADO

WATCH NUMBER 17. WATCH NUMBER 17 WILL NOT BE IN EFFECT AFTER 1040

PM CST.



DISCUSSION...THREATS OF ISOLATED TORNADOES WILL CONTINUE TO SPREAD

EWD ACROSS WW OVERNIGHT AHEAD OF STRONG MID/UPPER LEVEL TROUGH

MOVING OVER THE SRN PLAINS.  DEEP ASCENT AND STEEPENING MID LEVEL

LAPSE RATES SHOULD OVERCOME MODEST SURFACE-BASED INSTABILITY.  GIVEN

VERY STRONG LOW AND DEEP LAYER SHEAR IN PLACE...ROTATION WILL BE

COMMON WITH STRONGER CORES WITH THREATS OF LONGER-LIVED

LINES/SUPERCELLS.  ANY STORM WHICH CAN ROOT INTO MOISTENING BOUNDARY

LAYER WILL SUSTAIN A THREAT OF TORNADOES ALONG WITH DAMAGING WINDS

AND/OR HAIL.



AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL

SURFACE AND ALOFT TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND

GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 400.

MEAN STORM MOTION VECTOR 25030.





...EVANS

