Alert archive / Iowa / Tornado Watches in 2011
Tornado Watch 119
The Storm Prediction Center issued this tornado watch at Apr 9, 2011, 11:01 PM CDT for 25 counties in Iowa; Fillmore County, Houston County, Mower County, Minnesota; 5 counties in Wisconsin. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 9, 2011, 11:01 PM CDT (04:01 UTC)
- Expired
- Apr 10, 2011, 3:36 AM CDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 60 kt
All 33 counties
Allamakee County, IA, Bremer County, IA, Buena Vista County, IA, Butler County, IA, Cerro Gordo County, IA, Cherokee County, IA, Chickasaw County, IA, Clay County, IA, Clayton County, IA, Emmet County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Hancock County, IA, Howard County, IA, Humboldt County, IA, Kossuth County, IA, Mitchell County, IA, O'Brien County, IA, Palo Alto County, IA, Pocahontas County, IA, Winnebago County, IA, Winneshiek County, IA, Worth County, IA, Wright County, IA, Fillmore County, MN, Houston County, MN, Mower County, MN, Crawford County, WI, La Crosse County, WI, Monroe County, WI, Richland County, WI, Vernon County, WI
The radar
The Minneapolis radar (KMPX), 170 km from the middle of the area, began a volume at 04:01 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.
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 40%
- One or more EF2 to EF5 tornadoes
- 30%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 40%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 95%
Warnings issued inside it
16 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 9, 11:08 PM CDT | Severe Thunderstorm Warning | ARX | Mitchell | 52 min |
| Apr 9, 11:11 PM CDT | Tornado Warning | DMX | Kossuth, Palo Alto | 12 min |
| Apr 9, 11:11 PM CDT | Severe Thunderstorm Warning | FSD | Buena Vista, Clay | 34 min |
| Apr 9, 11:15 PM CDT | Severe Thunderstorm Warning | ARX | Howard, Winneshiek | 45 min |
| Apr 9, 11:24 PM CDT | Severe Thunderstorm Warning | DMX | Emmet, Kossuth, Palo Alto | 36 min |
| Apr 9, 11:27 PM CDT | Tornado Warning | FSD | Buena Vista, Clay | 18 min |
| Apr 9, 11:29 PM CDT | Tornado Warning | DMX | Hancock, Kossuth, Winnebago | 33 min |
| Apr 9, 11:36 PM CDT | Tornado Warning | DMX | Emmet, Palo Alto | 39 min |
| Apr 9, 11:39 PM CDT | Tornado Warning | FSD | Clay | 21 min |
| Apr 9, 11:41 PM CDT | Severe Thunderstorm Warning | DMX | Kossuth, Winnebago | 49 min |
| Apr 9, 11:55 PM CDT | Tornado Warning | DMX | Kossuth, Palo Alto | 35 min |
| Apr 9, 11:58 PM CDT | Severe Thunderstorm Warning | DMX | Winnebago, Worth | 32 min |
| Apr 10, 12:24 AM CDT | Severe Thunderstorm Warning | DMX | Hancock, Kossuth, Winnebago, Worth | 31 min |
| Apr 10, 12:47 AM CDT | Severe Thunderstorm Warning | FSD | Cherokee, Ida | 28 min |
| Apr 10, 12:53 AM CDT | Severe Thunderstorm Warning | DMX | Worth | 22 min |
| Apr 10, 1:38 AM CDT | Severe Thunderstorm Warning | DMX | Calhoun, Humboldt, Pocahontas, Webster | 52 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Minneapolis, MN (KMPX), launched 00:00Z, 4.0 hours before the alert went out and 170 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 612 m above ground
- 0-6 km bulk shear
- 54 kt
- 0-1 km storm-relative helicity
- 355 m²/s²
- 0-3 km storm-relative helicity
- 550 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 5.2
The text
As transmitted, in the capitals the NWS used until 2016.
727
WWUS20 KWNS 100405
SEL9
SPC WW 100405
IAZ000-MNZ000-WIZ000-101000-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 119
NWS STORM PREDICTION CENTER NORMAN OK
1100 PM CDT SAT APR 9 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
NORTHERN IOWA
FAR SOUTHEAST MINNESOTA
SOUTHWEST WISCONSIN
EFFECTIVE THIS SATURDAY NIGHT AND SUNDAY MORNING FROM 1100 PM
UNTIL 500 AM CDT.
TORNADOES...HAIL TO 1.5 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 40 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 40 MILES WEST SOUTHWEST OF
SPENCER IOWA TO 50 MILES EAST SOUTHEAST OF LA CROSSE WISCONSIN.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU9).
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 116...WW 117...WW 118...
DISCUSSION...LONG-LIVED SUPERCELLS THAT FORMED EARLIER THIS EVE IN
NW IA HAVE EVOLVED INTO SEVERAL COMPLEX CLUSTERS THAT ARE EXPECTED
TO CONTINUE MOVING ENE ALONG SLOWLY-ADVANCING WSW-ENE WARM FRONT NOW
OVER NRN IA. KDSM VWP SHOWS A 70 KT 3-4 KM DEEP SLY LLJ AIMED INTO
FRONTAL ZONE. COUPLED WITH WEAKER SELY NEAR-SFC FLOW OVER ERN
IA...AMPLE LOW LVL SHEAR APPEARS TO EXIST TO SUPPORT MAINTENANCE OF
EXISTING LOW-LVL MESO CYCLONES AND ASSOCIATED TORNADO THREAT INTO
RECOVERING BOUNDARY LAYER ENVIRONMENT OVER FAR NE IA...SE MN...AND
SW WI.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 26035.
...CORFIDISPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 9, 7:42 PM CDT | Severe Thunderstorm Watch | SPC | Allamakee, Chickasaw, Floyd, Howard, Mitchell, Winneshiek | 7 hr |
| Apr 9, 9:06 PM CDT | Mesoscale Discussion | SPC | Audubon, Buena Vista, Calhoun, Carroll, Cass, Cherokee and 31 more | 54 min |
| Apr 9, 10:43 PM CDT | Mesoscale Discussion | SPC | Allamakee, Black Hawk, Bremer, Buena Vista, Butler, Cerro Gordo and 25 more | 62 min |
| Apr 10, 1:26 AM CDT | Mesoscale Discussion | SPC | Allamakee, Buena Vista, Cerro Gordo, Chickasaw, Clay, Dickinson and 14 more | 64 min |
| Apr 10, 1:30 PM CDT | Mesoscale Discussion | SPC | Allamakee, Buchanan, Clayton, Delaware, Dubuque, Fayette and 5 more | 2 hr |
| Apr 10, 3:19 PM CDT | Tornado Watch | SPC | Allamakee, Clayton, Fayette, Howard, Winneshiek | 7 hr |
| Apr 10, 5:03 PM CDT | Mesoscale Discussion | SPC | Cedar, Clinton, Davis, Delaware, Des Moines, Dubuque and 12 more | 57 min |
| Apr 10, 6:05 PM CDT | Tornado Watch | SPC | Clinton, Des Moines, Jackson, Lee, Louisa, Muscatine and 1 more | 7 hr |
| Apr 9, 7:47 PM CDT | Severe Thunderstorm Watch | SPC | Cottonwood, Jackson, Lincoln, Lyon, Murray, Nobles and 2 more | 3 hr |
| Apr 10, 6:02 PM CDT | Mesoscale Discussion | SPC | Adams, Brown, Calumet, Columbia, Dane, Dodge and 26 more | 88 min |
Nearby
Tornado Watches in Iowa, 2011Tornado Watches in Wisconsin, 2011Tornado Watches in Minnesota, 2011Every tornado watch in 2011
Sources
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.