Severe Thunderstorm Watch 503

Issued

Jul 22, 2012, 5:45 PM CDT (22:45 UTC)

Expired

Jul 22, 2012, 9:47 PM CDT

In force

4 hr

Issued by

the Storm Prediction Center

Largest hail expected

2 in

Strongest gust expected

60 kt

Counties Big Stone County, MN, Traverse County, MN, Brown County, SD, Campbell County, SD, Clark County, SD, Codington County, SD, Corson County, SD, Day County, SD, Dewey County, SD, Edmunds County, SD, Faulk County, SD, Grant County, SD, Marshall County, SD, McPherson County, SD, Potter County, SD, Roberts County, SD, Spink County, SD, Walworth County, SD

The Aberdeen radar (KABR), 78 km from the middle of the area, began a volume at 22:49 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

40%

One or more hailstones of 2 inches or more

30%

Six or more combined severe hail and wind reports

60%

• Mesoscale Discussion 1545Jul 22, 4:38 PM CDT
• Mesoscale Discussion 1548Jul 22, 8:13 PM CDT

367 
WWUS20 KWNS 222249
SEL3
SPC WW 222249
MNZ000-NDZ000-SDZ000-230600-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 503
NWS STORM PREDICTION CENTER NORMAN OK
545 PM CDT SUN JUL 22 2012

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

       EXTREME WESTERN MINNESOTA
       SOUTHEAST NORTH DAKOTA
       NORTHERN AND NORTHEAST SOUTH DAKOTA

EFFECTIVE THIS SUNDAY AFTERNOON AND MONDAY MORNING FROM 545 PM
UNTIL 100 AM CDT.

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 40
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 45 MILES WEST OF
MOBRIDGE SOUTH DAKOTA TO 10 MILES NORTH OF ORTONVILLE MINNESOTA.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU3).

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 502...

DISCUSSION...SEVERAL ROBUST STORMS HAVE ERUPTED ALONG A SLOW MOVING
COLD FRONT ALIGNED WITH THE ND/SD BORDER LATE THIS AFTERNOON.
DESPITE PRONOUNCED MID LEVEL WARM LAYER...SUFFICIENT BOUNDARY LAYER
HEATING AND COMBINATION OF PERSISTENT CONVERGENCE ALONG THE FRONT
AND MOIST AXIS IN THIS AREA...AS WELL AS SUBTLE HEIGHT FALLS
ASSOCIATED WITH AN UPPER SHORT WAVE TROUGH IN CANADA...HAVE ALL
CONTRIBUTED TO THE RECENT INCREASE IN STORM DEVELOPMENT AND
COVERAGE. MODEL GUIDANCE IS NOT CONSISTENT WITH THIS CURRENT
DEVELOPMENT SUGGESTING GREATER UNCERTAINTY IN BOTH STORM PERSISTENCE
AND EVOLUTION. HOWEVER...MAGNITUDE OF CAPE AHEAD OF THE FRONT AND
ONGOING ACTIVITY...ALONG WITH MODEST EFFECTIVE SHEAR SUPPORTIVE OF
SUPERCELL STORM STRUCTURE AND UPDRAFT PERSISTENCE...WARRANT THE
ISSUANCE OF A WATCH. THESE STORMS WILL HAVE THE POTENTIAL TO PRODUCE
HAIL OF 1-2 INCHES IN DIAMETER AND DOWNBURST WINDS TO 60KT.

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 600. MEAN STORM
MOTION VECTOR 30020.


...CARBIN

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