Tornado Watch 778

Issued

Sep 12, 2005, 3:40 PM CDT (20:40 UTC)

Expired

Sep 12, 2005, 7:43 PM CDT

In force

4 hr

Issued by

the Storm Prediction Center

The Sioux Falls radar (KFSD), 78 km from the middle of the area, began a volume at 20:40 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.

• Mesoscale Discussion 2176Sep 12, 2:27 PM CDT
• Mesoscale Discussion 2180Sep 12, 6:47 PM CDT

000 
WWUS20 KWNS 122041
SEL8  
SPC WW 122041
IAZ000-MNZ000-SDZ000-130200-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 778
NWS STORM PREDICTION CENTER NORMAN OK
340 PM CDT MON SEP 12 2005

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

       NORTHWEST IOWA
       SOUTHWEST MINNESOTA
       SOUTHEAST SOUTH DAKOTA

EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 340 PM UNTIL 900
PM 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 APPROXIMATELY ALONG AND 70 STATUTE MILES
NORTH AND SOUTH OF A LINE FROM 40 MILES WEST OF MITCHELL SOUTH
DAKOTA TO 25 MILES SOUTH OF REDWOOD FALLS MINNESOTA.  FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU8).

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.

DISCUSSION...SURFACE LOW AND WARM FRONT APPEAR TO BE INCREASING
THUNDERSTORMS OVER SERN SD ATTM.  WARM SECTOR CONTINUES TO HEAT
WITHIN AXIS OF NEAR 70F SURFACE DEW POINTS...SUPPORTING 2000-2500
J/KG MLCAPE AND WEAK CINH.  THUNDERSTORMS ARE EXPECTED TO CONTINUE
INCREASING THROUGH THE LATE AFTERNOON AND EVENING WITH 40-50 KT OF
DEEP LAYER SHEAR SUPPORTING SUPERCELLS.  IN ADDITION TO WARM FRONT
EXTENDING NEWD INTO MN...AN OUTFLOW BOUNDARY EXTENDS NW-SE INTO SERN
SD/NWRN IA.  THUS LOW LEVEL SHEAR/HELICITY WILL BE ENHANCED AND
SUPPORT POTENTIAL FOR A FEW TORNADOES.

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 500.
MEAN STORM MOTION VECTOR 24035.


...EVANS

444,0985 451,0950 431,0950 424,0985

Tornado Watches in South Dakota, 2005Tornado Watches in Minnesota, 2005Tornado Watches in Iowa, 2005Every tornado watch in 2005

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.