

337 

WWUS20 KWNS 132055

SEL3

SPC WW 132055

MTZ000-NDZ000-SDZ000-WYZ000-140500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 413

NWS STORM PREDICTION CENTER NORMAN OK

250 PM MDT SAT JUL 13 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  FAR EASTERN MONTANA

  WESTERN AND CENTRAL NORTH DAKOTA

  WESTERN SOUTH DAKOTA

  NORTHEAST WYOMING



* EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 250 PM UNTIL

  1100 PM MDT.



* PRIMARY THREATS INCLUDE...

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

    2.5 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 80

STATUTE MILES EAST AND WEST OF A LINE FROM 65 MILES NORTHWEST OF

MINOT NORTH DAKOTA TO 20 MILES WEST SOUTHWEST OF RAPID CITY SOUTH

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

WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).



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 412...



DISCUSSION...TSTMS EXPECTED TO FORM IN THE NEXT 1-2 HOURS ALONG LEE

TROUGH IN FAR ERN MT/NE WY. OTHER STORMS MAY DEVELOP SWD INTO NW ND

FROM ACTIVITY NOW IN SE SK....WHILE ADDITIONAL STORMS MOVE AND

DEVELOP NEWD FROM THE BLACK HILLS. AMPLE DEEP SHEAR AND INSTABILITY

APPEAR PRESENT FOR SUPERCELLS WITH LARGE HAIL AND DMGG

WIND...ESPECIALLY IN WRN ND WHERE ASCENT WILL BE FOSTERED BY

GLANCING INFLUENCE OF SHORTWAVE IMPULSE NOW IN SW SK. A WEAKER

UPR-LVL DISTURBANCE NOW ENTERING WRN WY...AND TERRAIN

CIRCULATIONS...MAY FOSTER CONTINUED STORM DEVELOPMENT NEAR THE BLACK

HILLS. WHILE LOW-LVL SHEAR IS NOT STRONG THROUGHOUT THE WW...IT MAY

PROVE SUFFICIENT FOR LOW-LVL MESOCYCLONE DEVELOPMENT AND POSSIBLE

TORNADOES IN ND ...GIVEN PRESENCE OF A SUSTAINED...DISCRETE

SUPERCELL.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 25030.





...CORFIDI

