Severe Thunderstorm Watch 428

Issued

Jun 25, 2012, 3:07 PM MDT (21:07 UTC)

Expired

Jun 25, 2012, 10:22 PM MDT

In force

7 hr

Issued by

the Storm Prediction Center

Largest hail expected

2 in

Strongest gust expected

60 kt

The Billings radar (KBLX), 239 km from the middle of the area, began a volume at 21:10 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

40%

Six or more combined severe hail and wind reports

70%

• Mesoscale Discussion 1274Jun 25, 2:09 PM MDT
• Mesoscale Discussion 1278Jun 25, 5:26 PM MDT
• Mesoscale Discussion 1282Jun 25, 7:37 PM MDT

101 
WWUS20 KWNS 252109
SEL8
SPC WW 252109
MTZ000-SDZ000-WYZ000-260500-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 428
NWS STORM PREDICTION CENTER NORMAN OK
310 PM MDT MON JUN 25 2012

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

       SOUTHEAST MONTANA
       WESTERN SOUTH DAKOTA
       EASTERN WYOMING

EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 310 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 70
STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES NORTHWEST OF
MILES CITY MONTANA TO 135 MILES SOUTHEAST OF GILLETTE WYOMING.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU8).

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...

DISCUSSION...TSTMS ARE DEVELOPING THIS AFTERNOON ALONG THE HIGH
TERRAIN WITHIN A HOT...DEEPLY MIXED BOUNDARY LAYER...PERHAPS IN
RESPONSE TO A WEAK MIDLEVEL IMPULSE CRESTING RIDGE AXIS.  AIR MASS
MOISTENS/DESTABILIZES WITH EWD/NEWD EXTENT ACROSS THE WATCH
AREA...THOUGH CAP ALSO INCREASES.  SHOULD STORMS BECOME ROOTED IN
THE PROGRESSIVELY MORE UNSTABLE ENVIRONMENT...THE PRESENCE OF 30-40
KT OF DEEP-LAYER SHEAR WILL SUPPORT ORGANIZED STORM STRUCTURES
INCLUDING SUPERCELLS WITH A RISK FOR DAMAGING WINDS AND LARGE HAIL.

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 27020.


...MEAD

Severe Thunderstorm Watches in South Dakota, 2012Severe Thunderstorm Watches in Montana, 2012Severe Thunderstorm Watches in Wyoming, 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.