Tornado Watch 526

Issued

Jun 20, 2011, 6:53 PM CDT (23:53 UTC)

Expired

Jun 21, 2011, 12:53 AM CDT

In force

6 hr

Issued by

the Storm Prediction Center

Largest hail expected

2.5 in

Strongest gust expected

70 kt

The Omaha radar (KOAX), 78 km from the middle of the area, began a volume at 23:54 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

90%

One or more EF2 to EF5 tornadoes

50%

Ten or more severe wind reports

95%

One or more gusts of 65 knots or more

40%

Ten or more severe hail reports

95%

One or more hailstones of 2 inches or more

50%

Six or more combined severe hail and wind reports

95%

• Mesoscale Discussion 1325Jun 20, 3:59 PM CDT
• Mesoscale Discussion 1326Jun 20, 4:33 PM CDT
• Mesoscale Discussion 1328Jun 20, 5:55 PM CDT
• Mesoscale Discussion 1329Jun 20, 6:17 PM CDT
• Mesoscale Discussion 1331Jun 20, 7:46 PM CDT
• Mesoscale Discussion 1333Jun 20, 9:02 PM CDT
• Mesoscale Discussion 1334Jun 20, 10:22 PM CDT

701 
WWUS20 KWNS 210004
SEL6
SPC WW 210004
IAZ000-MNZ000-NEZ000-SDZ000-210700-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 526
NWS STORM PREDICTION CENTER NORMAN OK
655 PM CDT MON JUN 20 2011

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

       WESTERN AND CENTRAL IOWA
       SOUTHWEST MINNESOTA
       EASTERN AND NORTHERN NEBRASKA
       SOUTHEAST SOUTH DAKOTA

EFFECTIVE THIS MONDAY NIGHT AND TUESDAY MORNING FROM 655 PM UNTIL
200 AM CDT.

TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 105 STATUTE
MILES EAST AND WEST OF A LINE FROM 15 MILES SOUTHEAST OF
SHENANDOAH IOWA TO 35 MILES NORTHEAST OF MITCHELL SOUTH DAKOTA.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU6).

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 523...WW 524...WW 525...

DISCUSSION...ARC OF SUPERCELLS EXTENDING FROM NEAR ONL TO W OF OLU
TO W OF BIE EXPECTED TO ACCELERATE NNE/NE LATER THIS EVE AS
WRN/CNTRL KS VORT LOBE ASSUMES A MORE NEGATIVE TILT.  OTHER STORMS
MAY CONTINUE TO FORM ALONG N/S INVERTED TROUGH IN SE SD.  IN
ADDITION...WDLY SCTD STORMS MAY FORM LATER THIS EVE NEAR WEAK WARM
FRONT IN WRN/CNTRL IA.  THE MAIN ARC OF STORMS SHOULD EVOLVE INTO A
BROKEN SQLN/QLCS WITH TIME...BUT STRENGTH OF SHEAR AND DEGREE OF
INSTABILITY SUGGEST A CONTINUED POTENTIAL FOR ISOLD TORNADOES IN
ADDITION TO LARGE HAIL/HIGH WIND FROM EMBEDDED SUPERCELLS.
TORNADOES ALSO CANNOT BE RULED OUT WITH ACTIVITY ALONG INVERTED
TROUGH...AND WITH ANY STORMS THAT FORM AHEAD OF SQLN IN IA.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
550. MEAN STORM MOTION VECTOR 21035.


...CORFIDI

Tornado Watches in Iowa, 2011Tornado Watches in Nebraska, 2011Tornado Watches in South Dakota, 2011Every tornado watch in 2011

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.