Tornado Watch 657

Issued

Jul 29, 2006, 3:40 PM CDT (20:40 UTC)

Expired

Jul 29, 2006, 10:00 PM CDT

In force

6 hr

Issued by

the Storm Prediction Center

Largest hail expected

3 in

Strongest gust expected

60 kt

The Aberdeen radar (KABR), 96 km from the middle of the area, began a volume at 20:41 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

60%

One or more gusts of 65 knots or more

50%

Ten or more severe hail reports

60%

One or more hailstones of 2 inches or more

50%

Six or more combined severe hail and wind reports

90%

• Mesoscale Discussion 1664Jul 29, 1:51 PM CDT
• Mesoscale Discussion 1669Jul 29, 7:22 PM CDT
• Mesoscale Discussion 1671Jul 29, 9:24 PM CDT

000 
WWUS20 KWNS 292044
SEL7  
SPC WW 292044
MNZ000-NDZ000-SDZ000-300300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 657
NWS STORM PREDICTION CENTER NORMAN OK
340 PM CDT SAT JUL 29 2006

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

       WEST CENTRAL MINNESOTA
       SOUTHEASTERN NORTH DAKOTA
       NORTHEASTERN SOUTH DAKOTA

EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 340 PM UNTIL
1000 PM CDT.

TORNADOES...HAIL TO 3 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 75 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 45 MILES NORTHWEST OF
ABERDEEN SOUTH DAKOTA TO 20 MILES SOUTHEAST OF ALEXANDRIA
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 655...WW 656...

DISCUSSION...AIR MASS HAS BECOME EXTREMELY UNSTABLE WITH ONLY A VERY
WEAK CAP LEFT NEAR SURFACE FRONT INTO NERN SD/FAR SERN ND LATE THIS
AFTERNOON.  WITH MAXIMUM IN SURFACE CONVERGENCE AND FURTHER
HEATING...RAPID SEVERE THUNDERSTORM DEVELOPMENT IS EXPECTED IN THE
NEXT COUPLE HOURS WITHIN WW.  DEEP LAYER SHEAR REMAINS QUITE STRONG
AND WILL SUPPORT INTENSE SUPERCELLS...LIKELY EVOLVING INTO HP AND
BOW ECHO STRUCTURES AS THEY SHIFT ESEWD THROUGH THE EVENING GIVEN
RELATIVELY WEAK MID LEVEL STORM-RELATIVE WINDS.  THIS SHOULD ENHANCE
THE THREAT OF VERY STRONG/DAMAGING WINDS.  IN ADDITION...RICH
BOUNDARY LAYER MOISTURE AND STRONG LOW LEVEL HELICITY NEAR SURFACE
BOUNDARIES WILL ENHANCE THE POTENTIAL FOR A FEW TORNADOES ALONG WITH
SOME VERY LARGE HAIL.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 3 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 30020.


...EVANS

Tornado Watches in Minnesota, 2006Tornado Watches in South Dakota, 2006Tornado Watches in North Dakota, 2006Every tornado watch in 2006

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.