Tornado Watch 220

Issued

May 1, 2012, 2:59 PM CDT (19:59 UTC)

Expired

May 1, 2012, 9:24 PM CDT

In force

6 hr

Issued by

the Storm Prediction Center

Largest hail expected

2.5 in

Strongest gust expected

60 kt

The Sioux Falls radar (KFSD), 88 km from the middle of the area, began a volume at 19:59 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

30%

One or more gusts of 65 knots or more

30%

Ten or more severe hail reports

60%

One or more hailstones of 2 inches or more

40%

Six or more combined severe hail and wind reports

80%

• Mesoscale Discussion 646May 1, 2:30 PM CDT
• Mesoscale Discussion 652May 1, 6:11 PM CDT

465 
WWUS20 KWNS 012001
SEL0
SPC WW 012001
IAZ000-MNZ000-NDZ000-SDZ000-020300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 220
NWS STORM PREDICTION CENTER NORMAN OK
300 PM CDT TUE MAY 1 2012

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

       NORTHWEST IOWA
       CENTRAL AND SOUTHERN MINNESOTA
       FAR SOUTHEAST NORTH DAKOTA
       EASTERN SOUTH DAKOTA

EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 300 PM UNTIL
1000 PM CDT.

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 70 STATUTE
MILES EAST AND WEST OF A LINE FROM 40 MILES EAST OF YANKTON SOUTH
DAKOTA TO 40 MILES NORTHEAST OF ALEXANDRIA MINNESOTA.  FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU0).

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 217...WW 218...WW 219...

DISCUSSION...TSTMS CURRENTLY DEVELOPING ACROSS WARM SECTOR WITHIN
CONFLUENT LOW-LEVEL FLOW SHOULD CONTINUE TO INCREASE IN COVERAGE AND
INTENSITY AS REGION IS GLANCED BY MIDLEVEL SHORTWAVE TROUGH AND JET
STREAK MOVING THROUGH THE RED RIVER VALLEY.  THE COMBINATION OF
STEEP LAPSE RATES AND MODEST BOUNDARY LAYER MOISTURE ARE RESULTING
IN A MODERATELY UNSTABLE ENVIRONMENT THIS AFTERNOON WITH MLCAPE OF
1000-1500 J/KG.  WHEN COUPLED WITH STEADILY STRENGTHENING LOW AND
DEEP-LAYER SHEAR...SETUP WILL BECOME INCREASINGLY FAVORABLE FOR
SUPERCELLS CAPABLE OF LARGE HAIL...DAMAGING WINDS...AND A FEW
TORNADOES.

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 25030.


...MEAD

Tornado Watches in Minnesota, 2012Tornado Watches in South Dakota, 2012Tornado Watches in Iowa, 2012Every tornado 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.