

161 

WWUS20 KWNS 211951

SEL7

SPC WW 211951

COZ000-NEZ000-SDZ000-WYZ000-220300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 337

NWS STORM PREDICTION CENTER NORMAN OK

150 PM MDT FRI JUN 21 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  NORTHEAST COLORADO

  WESTERN NEBRASKA

  WESTERN SOUTH DAKOTA

  EASTERN WYOMING



* EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 150 PM UNTIL

  900 PM MDT.



* PRIMARY THREATS INCLUDE...

  SEVERAL LARGE HAIL EVENTS WITH A FEW VERY LARGE HAIL EVENTS TO 2

    INCHES IN DIAMETER POSSIBLE

  SEVERAL DAMAGING WIND GUSTS TO 70 MPH POSSIBLE

  A FEW TORNADOES POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70

STATUTE MILES EAST AND WEST OF A LINE FROM 70 MILES NORTHWEST OF

RAPID CITY SOUTH DAKOTA TO 60 MILES SOUTH SOUTHWEST OF SIDNEY

NEBRASKA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).



PRECAUTIONARY/PREPAREDNESS ACTIONS...



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 335...WW 336...



DISCUSSION...THUNDERSTORM INITIATION IS UNDERWAY WITHIN A MOIST

LOW-LEVEL UPSLOPE REGIME ACROSS THE NORTH CENTRAL HIGH PLAINS.

FURTHER DEVELOPMENT AND INTENSIFICATION IS EXPECTED THROUGH LATE

AFTERNOON AND EARLY EVENING...IN THE PRESENCE OF STRONG DEEP LAYER

SHEAR AND MODERATE TO STRONG INSTABILITY.  THE ENVIRONMENT IS

CONDUCIVE TO SUPERCELLS CAPABLE OF PRODUCING LARGE HAIL AND LOCALLY

STRONG WIND GUSTS.  A FEW...MAINLY BRIEF/WEAK...TORNADOES ARE NOT

OUT OF THE QUESTION.



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 25020.





...KERR

