

643 

WWUS20 KWNS 072304

SEL4

SPC WW 072304

MTZ000-NEZ000-SDZ000-WYZ000-080500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 484

NWS STORM PREDICTION CENTER NORMAN OK

505 PM MDT WED AUG 7 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  FAR SOUTHEAST MONTANA

  NORTHWEST NEBRASKA

  PARTS OF WESTERN AND SOUTHERN SOUTH DAKOTA

  PARTS OF EASTERN WYOMING



* EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 505 PM

  UNTIL 1100 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



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 75

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 30 MILES SOUTHWEST

OF GILLETTE WYOMING TO 60 MILES NORTH OF MULLEN NEBRASKA.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU4).



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 482...WW 483...



DISCUSSION...THUNDERSTORMS CONTINUE DEVELOPING IN A NORTHWEST TO

SOUTHEAST ZONE FROM SOUTHEAST MONTANA INTO SOUTH CENTRAL SOUTH

DAKOTA AND ADJACENT NORTHERN NEBRASKA...AHEAD OF AN UPPER VORT MAX

PROGRESSING NORTHEASTWARD ACROSS NORTHEAST COLORADO.  WITH 500 TO

1000 J/KG MIXED-LAYER CAPE ACROSS THE REGION AND SOME INCREASE IN

SHEAR EXPECTED OVER THE NEXT COUPLE OF HOURS AS MODEST DIURNAL

STRENGTHENING OF SLY LOW-LEVEL WINDS OCCURS...EXPECT ISOLATED THREAT

FOR HAIL AND LOCALLY DAMAGING WINDS OVER THE NEXT SEVERAL HOURS.



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 30030.





...GOSS

