Tornado Watch 677

Issued

Sep 21, 2007, 12:00 AM CDT (05:00 UTC)

Expired

Sep 21, 2007, 6:04 AM CDT

In force

6 hr

Issued by

the Storm Prediction Center

Largest hail expected

2.5 in

Strongest gust expected

60 kt

The Fargo/Grand Forks radar (KMVX), 151 km from the middle of the area, began a volume at 05:04 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

60%

One or more EF2 to EF5 tornadoes

50%

Ten or more severe wind reports

95%

One or more gusts of 65 knots or more

30%

Ten or more severe hail reports

95%

One or more hailstones of 2 inches or more

30%

Six or more combined severe hail and wind reports

95%

• Mesoscale Discussion 1996Sep 21, 3:29 AM CDT

000
WWUS20 KWNS 210459
SEL7  
SPC WW 210459
MNZ000-NDZ000-SDZ000-211200-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 677
NWS STORM PREDICTION CENTER NORMAN OK
1200 AM CDT FRI SEP 21 2007

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

       WESTERN AND CENTRAL MINNESOTA
       EASTERN NORTH DAKOTA
       NORTHEAST SOUTH DAKOTA

EFFECTIVE THIS FRIDAY MORNING FROM MIDNIGHT UNTIL 700 AM 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 95 STATUTE
MILES EITHER SIDE OF A LINE FROM 45 MILES WEST NORTHWEST OF
ORTONVILLE MINNESOTA TO 55 MILES EAST SOUTHEAST OF BEMIDJI
MINNESOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).

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 674...WW 675...WW 676...

DISCUSSION...TSTMS/SUPERCELLS EXPECTED TO INCREASE IN STRENGTHENING
WAA ZONE ACROSS ERN ND/NE SD AND WRN/CNTRL MN OVERNIGHT AS WIND
FIELDS INTENSIFY DOWNSTREAM FROM STRONG NRN STREAM DISTURBANCE NOW
OVER MT.  QUALITY OF MOISTURE INFLOW...DEVELOPING SFC LOW AND
EXISTING WEAK WSW-ENE-ORIENTED BOUNDARY PARALLEL TO STRONG WSWLY
DEEP SHEAR SUGGEST POTENTIAL FOR A FEW SUSTAINED SUPERCELLS WITH
LARGE HAIL/HIGH WIND AND POSSIBLE TORNADOES BEFORE ACTIVITY MERGES
INTO A LARGE CLUSTER TOWARD DAWN.

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 26040.


...CORFIDI

Tornado Watches in Minnesota, 2007Tornado Watches in North Dakota, 2007Tornado Watches in South Dakota, 2007Every tornado watch in 2007

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.