Tornado Watch 468

Issued

Jun 12, 2011, 1:49 PM MDT (19:49 UTC)

Expired

Jun 12, 2011, 8:00 PM MDT

In force

6 hr

Issued by

the Storm Prediction Center

Largest hail expected

2.5 in

Strongest gust expected

60 kt

The Rapid City radar (KUDX), 134 km from the middle of the area, began a volume at 19:51 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

40%

One or more EF2 to EF5 tornadoes

20%

Ten or more severe wind reports

50%

One or more gusts of 65 knots or more

30%

Ten or more severe hail reports

70%

One or more hailstones of 2 inches or more

50%

Six or more combined severe hail and wind reports

95%

• Mesoscale Discussion 1194Jun 12, 12:52 PM MDT
• Mesoscale Discussion 1198Jun 12, 5:07 PM MDT
• Mesoscale Discussion 1199Jun 12, 6:07 PM MDT

161 
WWUS20 KWNS 121954
SEL8
SPC WW 121954
MTZ000-NDZ000-SDZ000-WYZ000-130200-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 468
NWS STORM PREDICTION CENTER NORMAN OK
150 PM MDT SUN JUN 12 2011

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

       SOUTHEAST MONTANA
       SOUTHWEST NORTH DAKOTA
       WESTERN SOUTH DAKOTA
       NORTHEAST WYOMING

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 150 PM UNTIL 800
PM MDT.

TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 90 STATUTE
MILES EAST AND WEST OF A LINE FROM 35 MILES EAST NORTHEAST OF
BAKER MONTANA TO 70 MILES SOUTH OF RAPID CITY SOUTH DAKOTA.  FOR
A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU8).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND 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.

OTHER WATCH INFORMATION...CONTINUE...WW 467...

DISCUSSION...SURFACE HEATING IS REMOVING CONVECTIVE INHIBITION
ACROSS NE WY/SW SD NEAR THE SURFACE LOW AND WARM FRONT...WITH STORM
DEVELOPMENT EXPECTED BY 21-22Z.  STORM DEVELOPMENT WILL BE FURTHER
SUPPORTED BY THE APPROACH OF THE PRIMARY SHORTWAVE TROUGH OVER NW
WY/S CENTRAL MT...AND A SEPARATE SPEED MAX EJECTING NEWD FROM NRN
CO.  MODERATE INSTABILITY IS PRESENT IN THE WARM SECTOR /MLCAPE AOA
2000 J PER KG/...WHILE VERTICAL SHEAR IS FAVORABLE FOR SUPERCELLS
WITH LARGE HAIL.  THE MORE PROBABLE AREA FOR A COUPLE OF TORNADOES
WILL BE NE WY/NW SD WHERE LOW-LEVEL SHEAR AND MOISTURE ARE MAXIMIZED
ALONG THE WARM FRONT...AND WHERE INITIALLY DISCRETE STORMS ARE
EXPECTED.  LATER THIS AFTERNOON/EVENING...CONVECTION WILL LIKELY
GROW UPSCALE INTO A CLUSTER/MCS AND SPREAD NEWD WITH A CONTINUED
RISK FOR LARGE HAIL AND DAMAGING WINDS.

AVIATION...TORNADOES AND 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 23025.


...THOMPSON

Tornado Watches in South Dakota, 2011Tornado Watches in Montana, 2011Tornado Watches in North Dakota, 2011Every tornado watch in 2011

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.