Tornado Watch 626

Issued

Aug 20, 2002, 7:30 PM CDT (00:30 UTC)

Expired

Aug 21, 2002, 1:00 AM CDT

In force

6 hr

Issued by

the Storm Prediction Center

The Sioux Falls radar (KFSD), 87 km from the middle of the area, began a volume at 00:29 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.

000 
WWUS20 KWNS 210036
SEL6  
SPC WW 210030
IAZ000-MNZ000-SDZ000-210600-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 626
STORM PREDICTION CENTER NORMAN OK
730 PM CDT TUE AUG 20 2002

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

   NORTHWEST IOWA                               
   SOUTHWEST MINNESOTA                          
   EASTERN AND SOUTHERN SOUTH DAKOTA                       

EFFECTIVE THIS TUESDAY NIGHT AND WEDNESDAY MORNING FROM 730 PM
UNTIL 100 AM CDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 130 STATUTE MILES EAST AND WEST
OF A LINE FROM 60 MILES SOUTH SOUTHEAST OF MITCHELL SOUTH DAKOTA TO
40 MILES NORTH OF BROOKINGS SOUTH DAKOTA.

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...THIS TORNADO WATCH REPLACES SEVERE
THUNDERSTORM WATCH NUMBER 624.  WATCH NUMBER 624 WILL NOT BE IN
EFFECT AFTER 730 PM CDT.  CONTINUE...WW 625...

DISCUSSION...THUNDERSTORMS EXPECTED TO DEVELOP/INTENSIFY OVER WW
AREA DURING NEXT FEW HOURS AS APPROACHING UPPER DISTURBANCE NOW
OVER NEB AND NOCTURNAL STRENGTHENING OF LOW LEVEL JET ENHANCE LARGE
SCALE ASCENT OVER REGION.  AMPLE /40 KT/ DEEP SHEAR WILL EXIST FOR
SUPERCELLS THROUGHOUT WW.  TORNADO THREAT WILL BE GREATEST INVOF
SLOW MOVING WARM FRONT...WHERE LOW LCLS AND LOCALLY ENHANCED LOW
LEVEL SHEAR WILL EXIST.  ACTIVITY SHOULD EVOLVE INTO LINEAR MCS
WITH LEWPS/SMALL BOWS LATER TONIGHT.  

AVIATION...TORNADOES AND 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 550. 
MEAN STORM MOTION VECTOR 24030.

...CORFIDI

445,0941 425,0950 425,1000 445,0992

Tornado Watches in South Dakota, 2002Tornado Watches in Minnesota, 2002Tornado Watches in Iowa, 2002Every tornado watch in 2002

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.