

293 

WWUS20 KWNS 041946

SEL0

SPC WW 041946

MTZ000-NDZ000-SDZ000-WYZ000-050200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 220

NWS STORM PREDICTION CENTER NORMAN OK

145 PM MDT WED JUN 4 2014



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  SOUTHEAST MONTANA

  SOUTHWEST NORTH DAKOTA

  WESTERN SOUTH DAKOTA

  EASTERN WYOMING



* EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 145 PM

  UNTIL 800 PM MDT.



* PRIMARY THREATS INCLUDE...

  ISOLATED VERY LARGE HAIL EVENTS TO 2 INCHES IN DIAMETER POSSIBLE

  ISOLATED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60

STATUTE MILES EAST AND WEST OF A LINE FROM 30 MILES NORTHWEST OF

BAKER MONTANA TO 10 MILES SOUTH SOUTHWEST OF CHEYENNE WYOMING.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU0).



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 218...WW 219...



DISCUSSION...VIGOROUS STORM DEVELOPMENT TAKING PLACE ACROSS THE

HIGHER TERRAIN OF MT/WY ATTM AS A SHORTWAVE TROUGH CROSSES THE

CONTINENTAL DIVIDE AND AIDS LARGE SCALE ASCENT. EXPECT THIS ACTIVITY

TO SPREAD EAST INTO AN AXIS OF MODEST INSTABILITY AND SUPPORTIVE

STORM-RELATIVE INFLOW AND UPSLOPE FLOW FROM SERN MT TO SERN WY.

DEEP-LAYER VERTICAL SHEAR IN THE 30-40KT RANGE WILL SUPPORT UPDRAFT

ORGANIZATION AND PERSISTENCE WITH ATTENDANT THREATS OF LARGE HAIL

AND HIGH WINDS WITH TIME. SOME TORNADO POTENTIAL WILL EXIST FOR ANY

DISCRETE CELLS GIVEN SOME HODOGRAPH CURVATURE IN THE STORM UPDRAFT

LAYER.



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 450. MEAN STORM

MOTION VECTOR 27030.





...CARBIN

