

513 

WWUS20 KWNS 111913

SEL6

SPC WW 111913

MTZ000-WYZ000-120300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 296

NWS STORM PREDICTION CENTER NORMAN OK

110 PM MDT TUE JUN 11 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  SOUTHERN AND EASTERN MONTANA

  NORTHEAST WYOMING



* EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 110 PM UNTIL

  900 PM MDT.



* PRIMARY THREATS INCLUDE...

  NUMEROUS LARGE HAIL EVENTS LIKELY WITH A FEW VERY LARGE HAIL

    EVENTS TO 3 INCHES IN DIAMETER POSSIBLE

  SEVERAL DAMAGING WIND GUSTS WITH A FEW SIGNIFICANT GUSTS TO 75

    MPH POSSIBLE

  A FEW TORNADOES POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 115

STATUTE MILES EAST AND WEST OF A LINE FROM 80 MILES NORTH

NORTHWEST OF MILES CITY MONTANA TO 65 MILES SOUTHWEST OF GILLETTE

WYOMING.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).



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.



&&



DISCUSSION...TSTMS EXPECTED TO FORM OVER THE HIGHER TERRAIN OF NRN

WY AND SRN MT DURING THE NEXT FEW HOURS IN RESPONSE TO CONTINUED SFC

HEATING...PERSISTENT LOW-LVL MOISTURE INFLOW...AND ASCENT ASSOCIATED

WITH PASSING UPR-LVL TROUGH. CURRENT AND FORECAST WIND PROFILES AND

THERMODYNAMIC DATA APPEAR FAVORABLE FOR SUPERCELLS WITH VERY LARGE

HAIL AND LOCALLY DMGG WIND...ESPECIALLY IN SE MT AND NE WY. IN THE

LATTER AREA...AN INCREASING RISK FOR TORNADOES IS ALSO EXPECTED AS

LOW-LVL MOISTURE CONTINUES TO INCREASE BENEATH STRENGTHENING MID-LVL

COLD ADVECTION AND ASCENT. THIS PART OF THE WW LIKELY WILL REQUIRE

UPGRADE TO TORNADO A BIT LATER THIS AFTN.



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

TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM

MOTION VECTOR 29020.





...CORFIDI

