Severe Thunderstorm Watch 421

Issued

Jun 24, 2012, 8:31 AM MDT (14:31 UTC)

Expired

Jun 24, 2012, 1:30 PM MDT

In force

5 hr

Issued by

the Storm Prediction Center

Largest hail expected

2 in

Strongest gust expected

60 kt

Counties Daniels County, MT, Richland County, MT, Roosevelt County, MT, Sheridan County, MT, Billings County, ND, Burleigh County, ND, Dunn County, ND, Emmons County, ND, Grant County, ND, Hettinger County, ND, McKenzie County, ND, McLean County, ND, Mercer County, ND, Morton County, ND, Mountrail County, ND, Oliver County, ND, Sioux County, ND, Stark County, ND, Williams County, ND

Two or more tornadoes

10%

One or more EF2 to EF5 tornadoes

5%

Ten or more severe wind reports

40%

One or more gusts of 65 knots or more

20%

Ten or more severe hail reports

40%

One or more hailstones of 2 inches or more

20%

Six or more combined severe hail and wind reports

70%

• Mesoscale Discussion 1257Jun 24, 8:16 AM MDT
• Mesoscale Discussion 1260Jun 24, 11:24 AM MDT

146 
WWUS20 KWNS 241434
SEL1
SPC WW 241434
MTZ000-NDZ000-242100-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 421
NWS STORM PREDICTION CENTER NORMAN OK
835 AM MDT SUN JUN 24 2012

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

       NORTHEAST MONTANA
       WESTERN AND CENTRAL NORTH DAKOTA

EFFECTIVE THIS SUNDAY MORNING AND AFTERNOON FROM 835 AM UNTIL 300
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 50
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 25 MILES NORTH
NORTHWEST OF WOLF POINT MONTANA TO 15 MILES EAST NORTHEAST OF
BISMARCK NORTH DAKOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE
THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).

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...SEVERE STORMS CROSSING THE NERN MT/NWRN ND BORDER ARE
EXPECTED TO PROPAGATE ESEWD ALONG THE 700 MB TEMPERATURE GRADIENT ON
THE NERN EDGE OF THE EML/CAPPING INVERSION.  ADDITIONAL STRONG
CONVECTION NE OF GGW MAY ALSO INTENSIFY AND TRACK ESEWD IN THE WAKE
OF THE STORM ALONG THE BORDER.  VERY STEEP MID LEVEL LAPSE RATES AND
AMPLE ELEVATED MOISTURE IS RESULTING IN STRONG INSTABILITY BASED
ABOVE THE PBL.  STRONG EFFECTIVE BULK SHEAR WILL MAINTAIN STORM
ORGANIZATION AND INTENSITY...WITH CONTINUED POTENTIAL FOR LARGE HAIL
AND DAMAGING WIND GUSTS.

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 29030.


...WEISS

Severe Thunderstorm Watches in North Dakota, 2012Severe Thunderstorm Watches in Montana, 2012Every severe thunderstorm watch in 2012

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive.