Severe Thunderstorm Watch 430

Issued

Jun 25, 2012, 4:01 PM MDT (22:01 UTC)

Expired

Jun 26, 2012, 1:00 AM MDT

In force

9 hr

Issued by

the Storm Prediction Center

Largest hail expected

2.5 in

Strongest gust expected

60 kt

The Great Falls radar (KTFX), 170 km from the middle of the area, began a volume at 22:03 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

Two or more tornadoes

20%

One or more EF2 to EF5 tornadoes

5%

Ten or more severe wind reports

30%

One or more gusts of 65 knots or more

30%

Ten or more severe hail reports

30%

One or more hailstones of 2 inches or more

50%

Six or more combined severe hail and wind reports

80%

• Mesoscale Discussion 1274Jun 25, 2:09 PM MDT
• Mesoscale Discussion 1276Jun 25, 3:35 PM MDT
• Mesoscale Discussion 1280Jun 25, 7:12 PM MDT
• Mesoscale Discussion 1284Jun 25, 10:27 PM MDT
• Mesoscale Discussion 1286Jun 26, 12:23 AM MDT

951 
WWUS20 KWNS 252159
SEL0
SPC WW 252159
MTZ000-260700-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 430
NWS STORM PREDICTION CENTER NORMAN OK
400 PM MDT MON JUN 25 2012

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

       NORTHERN MONTANA

EFFECTIVE THIS MONDAY AFTERNOON AND TUESDAY MORNING FROM 400 PM
UNTIL 100 AM MDT.

HAIL TO 2.5 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 75
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 55 MILES SOUTH
SOUTHWEST OF CUT BANK MONTANA TO 15 MILES NORTH NORTHEAST OF
SIDNEY MONTANA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU0).

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 426...WW 427...WW
428...WW 429...

DISCUSSION...TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND
INTENSITY ACROSS THE WATCH AREA LATE THIS AFTERNOON INTO TONIGHT AS
LARGE-SCALE FORCING STRENGTHENS AHEAD OF A MIDLEVEL JET STREAK
PROPAGATING NNEWD THROUGH THE NRN INTERMOUNTAIN REGION.  AIR MASS
ALONG TO THE N OF WNW-ESE ORIENTED SURFACE FRONT IS QUITE MOIST FOR
THE ELEVATION WITH MLCAPE VALUES APPROACHING 1500-3000+ J/KG.  WHEN
COUPLED WITH 35-50 KT OF EFFECTIVE BULK SHEAR...SETUP WILL FAVOR
SUPERCELLS AND BOWING STRUCTURES CAPABLE OF LARGE HAIL AND DAMAGING
WINDS.  A TORNADO IS ALSO POSSIBLE.

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 26020.


...MEAD

Severe 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; radar from the NEXRAD Level II archive.