

941 

WWUS20 KWNS 050821

SEL6

SPC WW 050821

SDZ000-WYZ000-051500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 246

NWS STORM PREDICTION CENTER NORMAN OK

215 AM MDT SAT MAY 5 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN AND CENTRAL SOUTH DAKOTA

       NORTHEAST WYOMING



EFFECTIVE THIS SATURDAY MORNING FROM 215 AM UNTIL 900 AM MDT.



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 70

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 65 MILES WEST OF

RAPID CITY SOUTH DAKOTA TO 35 MILES SOUTHEAST OF PIERRE SOUTH

DAKOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED

WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).



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 243...WW 245...



DISCUSSION...A SERIES OF ELEVATED TSTMS...INCLUDING SOME SUSTAINED

STORMS AND POSSIBLE SUPERCELLS...EXPECTED IN WW AREA THROUGH LATER

THIS MORNING AS ELEVATED WAA/ASCENT INCREASE DOWNSTREAM FROM NRN GRT

BASIN UPR TROUGH.  STORM BASES EXPECTED TO BE AROUND 700 MB...BUT

WILL STILL TAP FAIRLY RICH MOIST LAYER...WITH PW AOA 1 INCH.

COUPLED WITH SIZABLE...LARGELY UNIDIRECTIONAL CLOUD LAYER

SHEAR...SETUP COULD YIELD A FEW EPISODES OF LARGE HAIL.



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 500. MEAN STORM

MOTION VECTOR 26030.





...CORFIDI

