

698 

WWUS20 KWNS 302212

SEL2

SPC WW 302212

MTZ000-WYZ000-010500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 432

NWS STORM PREDICTION CENTER NORMAN OK

410 PM MDT WED JUN 30 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EASTERN MONTANA

       EXTREME NORTH CENTRAL WYOMING



EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 410 PM UNTIL

1100 PM MDT.



HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 110

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

BILLINGS MONTANA TO 75 MILES NORTHWEST OF GLENDIVE MONTANA.  FOR

A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU2).



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 430...WW 431...



DISCUSSION...STRONG/SEVERE THUNDERSTORMS OVER SOUTH CENTRAL MT AND

EXTREME NORTH CENTRAL WY ARE LIKELY TO PROGRESS NEWD THROUGH THE

EVENING HOURS ALONG THE SOUTHEAST EDGE OF STRONGER FLOW ALOFT.  SWLY

MID LEVEL WINDS OF 40-50 KT ARE CONTRIBUTING TO SUFFICIENT DEEP

LAYER SHEAR TO ENHANCE STORM ORGANIZATION AND INTENSITY...WITH STORM

ROTATION POSSIBLE IN STRONGER CELLS.  LOW LEVEL MOISTURE INCREASES

IN EASTERN MT WHERE SURFACE DEW POINTS ARE IN THE MID/UPPER 50S

SUPPORTING MLCAPE OF 1000-1500 J/KG...INDICATING SEVERE POTENTIAL

WILL SPREAD NEWD WITH TIME.



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 24030.





...WEISS

