Tornado Watch 230

Issued

May 4, 2007, 9:22 PM CDT (02:22 UTC)

Expired

May 5, 2007, 7:54 AM CDT

In force

11 hr

Issued by

the Storm Prediction Center

Largest hail expected

1 in

Strongest gust expected

60 kt

The Sioux Falls radar (KFSD), 120 km from the middle of the area, began a volume at 02:22 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

30%

One or more EF2 to EF5 tornadoes

20%

Ten or more severe wind reports

30%

One or more gusts of 65 knots or more

5%

Ten or more severe hail reports

20%

One or more hailstones of 2 inches or more

5%

Six or more combined severe hail and wind reports

60%

• Mesoscale Discussion 687May 4, 6:20 PM CDT
• Mesoscale Discussion 690 Tornado watch 226May 4, 8:49 PM CDT
• Mesoscale Discussion 695May 5, 1:23 AM CDT
• Mesoscale Discussion 696May 5, 3:00 AM CDT
• Mesoscale Discussion 697May 5, 6:59 AM CDT

000
WWUS20 KWNS 050224
SEL0  
SPC WW 050224
NEZ000-SDZ000-050900-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 230
NWS STORM PREDICTION CENTER NORMAN OK
925 PM CDT FRI MAY 4 2007

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

       NORTHEAST NEBRASKA
       EASTERN SOUTH DAKOTA

EFFECTIVE THIS FRIDAY NIGHT AND SATURDAY MORNING FROM 925 PM
UNTIL 400 AM CDT.

TORNADOES...HAIL TO 1 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 50 STATUTE
MILES EAST AND WEST OF A LINE FROM 75 MILES SOUTH SOUTHWEST OF
MITCHELL SOUTH DAKOTA TO 45 MILES NORTH NORTHWEST OF BROOKINGS
SOUTH DAKOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU0).

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 TORNADO
WATCH NUMBER 226. WATCH NUMBER 226 WILL NOT BE IN EFFECT AFTER
925 PM CDT. CONTINUE...WW 227...WW 228...WW 229...

DISCUSSION...SW/NE ORIENTED INVERTED TROUGH EXPECTED TO REMAIN A
FOCUS FOR STORM/POSSIBLE SUPERCELL DEVELOPMENT THROUGH EARLY
SATURDAY FROM N CNTRL NEB INTO E CNTRL SD.  WHILE LEAD UPPER IMPULSE
THAT WAS IN PART RESPONSIBLE FOR STORMS NOW OVER THE REGION IS
LIFTING NNE INTO ND...TRAILING SFC COOL AIR SURGE AND NOCTURNAL
STRENGTHENING OF LLJ WILL MAINTAIN FAVORABLE ENVIRONMENT FOR LOW
LEVEL UPDRAFT DEVELOPMENT AND ROTATION.  THUS THREAT MAY PERSIST FOR
ISOLATED TORNADOES/LOCALLY DAMAGING WIND DESPITE LOSS OF SFC
HEATING.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500.
MEAN STORM MOTION VECTOR 20030.


...CORFIDI

Tornado Watches in South Dakota, 2007Tornado Watches in Nebraska, 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.