Severe Thunderstorm Watch 581

Issued

Aug 15, 2012, 3:25 PM CDT (20:25 UTC)

Expired

Aug 15, 2012, 11:00 PM CDT

In force

8 hr

Issued by

the Storm Prediction Center

Largest hail expected

2.5 in

Strongest gust expected

65 kt

The Duluth radar (KDLH), 151 km from the middle of the area, began a volume at 20:26 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

90%

One or more gusts of 65 knots or more

50%

Ten or more severe hail reports

80%

One or more hailstones of 2 inches or more

50%

Six or more combined severe hail and wind reports

95%

• Mesoscale Discussion 1766Aug 15, 2:56 PM CDT
• Mesoscale Discussion 1768Aug 15, 5:49 PM CDT
• Mesoscale Discussion 1770Aug 15, 8:20 PM CDT

449 
WWUS20 KWNS 152030
SEL1  
SPC WW 152030
MNZ000-SDZ000-WIZ000-LSZ000-160400-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 581
NWS STORM PREDICTION CENTER NORMAN OK
330 PM CDT WED AUG 15 2012

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

       MINNESOTA
       NORTHEAST SOUTH DAKOTA
       NORTHWEST WISCONSIN
       LAKE SUPERIOR

EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 330 PM UNTIL
1100 PM CDT.

HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 75
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 105
STATUTE MILES EITHER SIDE OF A LINE FROM 30 MILES EAST SOUTHEAST
OF INTERNATIONAL FALLS MINNESOTA TO 15 MILES SOUTHWEST OF REDWOOD
FALLS MINNESOTA.  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.

OTHER WATCH INFORMATION...CONTINUE...WW 580...

DISCUSSION...A STRONG COLD FRONT WILL SWEEP EAST AND SOUTHEAST
ACROSS MN...ERN SD AND INTO NWRN WI THROUGH THE EVENING HOURS.
AIRMASS AHEAD OF THE FRONT HAS BECOME MODERATELY TO STRONGLY
UNSTABLE WITH LATEST MLCAPE VALUES RANGING FROM 1000 J/KG ACROSS THE
WRN PORTION OF THE ARROWHEAD OF MN TO OVER 2000 J/KG ACROSS PARTS OF
WRN MN AND NERN SD. THIS INSTABILITY IS EXPECTED TO FUEL RAPID AND
ROBUST TSTM DEVELOPMENT ALONG THE FRONT OVER THE NEXT FEW HOURS.
THIS DEVELOPMENT WILL OCCUR COINCIDENT WITH STRENGTHENING DEEP-LAYER
SHEAR AND INCREASING ASCENT THAT SHOULD FURTHER SUPPORT STORM
ORGANIZATION AND UPDRAFT PERSISTENCE. INITIAL DISCRETE STORMS MAY BE
SUPERCELLULAR WITH ROTATING UPDRAFTS AND LARGE HAIL POTENTIAL. WITH
TIME...STORMS SHOULD BECOME INCREASINGLY LINEAR ALONG OR JUST AHEAD
OF THE FRONT WITH A SEVERE QLCS/SQUALL LINE EVOLVING. HIGH/DAMAGING
WINDS MAY ACCOMPANY THE SQUALL LINE INTO THE EVENING HOURS ACROSS
PORTIONS OF SRN MN AS WELL AS WRN WI.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 26035.


...CARBIN

Severe Thunderstorm Watches in Minnesota, 2012Severe Thunderstorm Watches in Wisconsin, 2012Severe Thunderstorm Watches in South Dakota, 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.