Tornado Watch 577

Issued

Jul 13, 2009, 12:34 PM MDT (18:34 UTC)

Expired

Jul 13, 2009, 8:55 PM MDT

In force

8 hr

Issued by

the Storm Prediction Center

Largest hail expected

2.5 in

Strongest gust expected

60 kt

Counties Bennett County, SD, Butte County, SD, Custer County, SD, Fall River County, SD, Haakon County, SD, Harding County, SD, Hughes County, SD, Jackson County, SD, Jones County, SD, Lawrence County, SD, Lyman County, SD, Meade County, SD, Mellette County, SD, Pennington County, SD, Perkins County, SD, Stanley County, SD, Todd County, SD, Tripp County, SD, Ziebach County, SD

The Rapid City radar (KUDX), 75 km from the middle of the area, began a volume at 18:37 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

30%

Ten or more severe wind reports

50%

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

50%

Six or more combined severe hail and wind reports

90%

• Mesoscale Discussion 1545Jul 13, 9:38 AM MDT
• Mesoscale Discussion 1546Jul 13, 11:43 AM MDT
• Mesoscale Discussion 1552Jul 13, 5:05 PM MDT
• Mesoscale Discussion 1554Jul 13, 7:47 PM MDT

432 
WWUS20 KWNS 131836
SEL7  
SPC WW 131836
SDZ000-140300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 577
NWS STORM PREDICTION CENTER NORMAN OK
1235 PM MDT MON JUL 13 2009

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

       PARTS OF CENTRAL AND WESTERN SOUTH DAKOTA

EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 1235 PM UNTIL
900 PM MDT.

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 80 STATUTE
MILES EAST AND WEST OF A LINE FROM 55 MILES EAST NORTHEAST OF
BUFFALO SOUTH DAKOTA TO 70 MILES SOUTH OF PHILIP SOUTH DAKOTA. 
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 576...

DISCUSSION...THREAT FOR A FEW TORNADOES WILL INCREASE THIS AFTERNOON
AS THE LOW LEVELS DESTABILIZE AND THE WARM FRONT LIFTS SLOWLY NWD
ACROSS CENTRAL SD.  ALONG WITH THE EXISTING SUPERCELL NW OF
PIR...OTHER STORMS NOW FORMING WITH ANOTHER LEAD SHORTWAVE TROUGH
FROM RAP NWD WILL LIKELY EVOLVE INTO SUPERCELLS WITH AN INCREASING
TORNADO THREAT...AS STORMS MOVE EWD AND INTERACT WITH THE ZONE OF
ENHANCED LOW-LEVEL SHEAR AND MOISTURE ALONG THE WARM FRONT.  ANOTHER
ROUND OF SEVERE STORMS WILL BE POSSIBLE LATER THIS EVENING AS
CONVECTION MOVES INTO SD FROM WY/MT IN ASSOCIATION WITH THE MAIN
SHORTWAVE TROUGH.

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 31020.


...THOMPSON

Tornado Watches in South Dakota, 2009Every tornado watch in 2009

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.