Tornado Watch 488

Issued

Jun 21, 2009, 3:17 PM CDT (20:17 UTC)

In effect from

Jun 21, 2009, 3:26 PM CDT

Expired

Jun 21, 2009, 11:00 PM CDT

In force

8 hr

Issued by

the Storm Prediction Center

Largest hail expected

2 in

Strongest gust expected

60 kt

The Des Moines radar (KDMX), 142 km from the middle of the area, began a volume at 20:16 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

30%

Ten or more severe wind reports

50%

One or more gusts of 65 knots or more

30%

Ten or more severe hail reports

40%

One or more hailstones of 2 inches or more

30%

Six or more combined severe hail and wind reports

80%

• Mesoscale Discussion 1259Jun 21, 12:33 PM CDT
• Mesoscale Discussion 1268Jun 21, 6:51 PM CDT
• Mesoscale Discussion 1270Jun 21, 9:06 PM CDT

965 
WWUS20 KWNS 212027
SEL8  
SPC WW 212027
IAZ000-MNZ000-220300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 488
NWS STORM PREDICTION CENTER NORMAN OK
330 PM CDT SUN JUN 21 2009

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

       NORTHERN AND CENTRAL IOWA
       FAR SOUTHERN MINNESOTA

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 330 PM UNTIL
1000 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 60 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 50 MILES SOUTHWEST OF
WORTHINGTON MINNESOTA TO 30 MILES NORTHEAST OF CEDAR RAPIDS IOWA.
 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...THUNDERSTORMS EXPECTED TO INTENSIFY QUICKLY LATE TODAY
ALONG AND JUST SOUTH OF A SURFACE WARM FRONT EXTENDING NW-SE ACROSS
IA.  AIR MASS WILL BE MODERATELY UNSTABLE WITH 30-40 KT EFFECTIVE
SHEAR SUPPORTIVE OF SUPERCELLS AND EVOLUTION INTO SMALL BOW ECHOES. 
LOW LEVEL SHEAR WILL BE MORE THAN ADEQUATE FOR A THREAT OF TORNADOES
WITH ADDITIONAL LARGE HAIL/DAMAGING WIND THREATS THROUGH THE MID TO
LATE EVENING.

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 28020.


...EVANS

Tornado Watches in Iowa, 2009Tornado Watches in Minnesota, 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.