Alert archive / Iowa / Tornado Watches in 2004
Tornado Watch 244
The Storm Prediction Center issued this tornado watch at May 21, 2004, 9:55 PM CDT for 20 counties in Iowa; 7 counties in Nebraska. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- May 21, 2004, 9:55 PM CDT (02:55 UTC)
- Expired
- May 22, 2004, 2:00 AM CDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
All 27 counties
Audubon County, IA, Boone County, IA, Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cherokee County, IA, Crawford County, IA, Dallas County, IA, Greene County, IA, Guthrie County, IA, Harrison County, IA, Humboldt County, IA, Ida County, IA, Monona County, IA, Plymouth County, IA, Pocahontas County, IA, Sac County, IA, Shelby County, IA, Webster County, IA, Woodbury County, IA, Burt County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Dodge County, NE, Thurston County, NE, Washington County, NE
The radar
The Omaha radar (KOAX), 121 km from the middle of the area, began a volume at 02:57 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.
Warnings issued inside it
19 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 21, 9:59 PM CDT | Severe Thunderstorm Warning | FSD | Buena Vista, Cherokee, Woodbury | 31 min |
| May 21, 10:00 PM CDT | Tornado Warning | OAX | Thurston | 45 min |
| May 21, 10:14 PM CDT | Severe Thunderstorm Warning | FSD | Plymouth | 31 min |
| May 21, 10:15 PM CDT | Tornado Warning | OAX | Cuming, Wayne | 45 min |
| May 21, 10:29 PM CDT | Severe Thunderstorm Warning | FSD | Buena Vista | 16 min |
| May 21, 10:39 PM CDT | Severe Thunderstorm Warning | DMX | Palo Alto, Pocahontas | 51 min |
| May 21, 10:46 PM CDT | Tornado Warning | OAX | Thurston | 44 min |
| May 21, 11:00 PM CDT | Severe Thunderstorm Warning | OAX | Monona | 45 min |
| May 21, 11:07 PM CDT | Severe Thunderstorm Warning | FSD | Ida, Woodbury | 23 min |
| May 21, 11:10 PM CDT | Severe Thunderstorm Warning | DMX | Humboldt, Kossuth | 50 min |
| May 21, 11:16 PM CDT | Severe Thunderstorm Warning | DMX | Sac | 44 min |
| May 21, 11:18 PM CDT | Severe Thunderstorm Warning | OAX | Cuming | 42 min |
| May 21, 11:30 PM CDT | Flash Flood Warning | OAX | Thurston, Wayne | 6 hr |
| May 21, 11:36 PM CDT | Severe Thunderstorm Warning | OAX | Thurston | 39 min |
| May 21, 11:39 PM CDT | Severe Thunderstorm Warning | FSD | Dakota, Dixon | 36 min |
| May 21, 11:50 PM CDT | Severe Thunderstorm Warning | FSD | Woodbury | 25 min |
| May 21, 11:59 PM CDT | Severe Thunderstorm Warning | OAX | Cuming | 46 min |
| May 22, 12:03 AM CDT | Flash Flood Warning | FSD | Cherokee, Clay, O'Brien, Plymouth | 87 min |
| May 22, 12:28 AM CDT | Flash Flood Warning | OAX | Cuming | 6 hr |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Omaha, NE (KOAX), launched 00:00Z, 2.9 hours before the alert went out and 121 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
- 2589 J/kg
- Mixed-layer CIN
- -33 J/kg
- Mixed-layer LCL
- 1462 m above ground
- 0-6 km bulk shear
- 35 kt
- 0-1 km storm-relative helicity
- 64 m²/s²
- 0-3 km storm-relative helicity
- 166 m²/s²
- Significant tornado parameter
- 0.6
- Supercell composite
- 6.9
The text
As transmitted, in the capitals the NWS used until 2016.
000
WWUS20 KWNS 220252
SEL4
SPC WW 220255
IAZ000-NEZ000-SDZ000-220700-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 244
NWS STORM PREDICTION CENTER NORMAN OK
955 PM CDT FRI MAY 21 2004
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
NORTHWEST IOWA
NORTHEAST NEBRASKA
SOUTHEAST CORNER OF SOUTH DAKOTA
EFFECTIVE THIS FRIDAY NIGHT AND SATURDAY MORNING FROM 955 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 ALONG AND 45 STATUTE MILES NORTH AND
SOUTH OF A LINE FROM 35 MILES SOUTHWEST OF SIOUX CITY IOWA TO 25
MILES SOUTHEAST OF FORT DODGE IOWA.
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 236. WATCH NUMBER 236 WILL NOT BE IN EFFECT AFTER 955
PM CDT. CONTINUE...WW 240...WW 241...WW 242...WW 243...
DISCUSSION...TORNADIC SUPERCELLS CONTINUE TO DEVELOP IN AREA OF
STRONG LOW LEVEL CONVERGENCE VICINITY E/W BOUNDARY ACROSS NRN IA.
WITH VERY UNSTABLE AIR MASS AND STRONG VEERING SHEAR
PROFILES...TORNADO THREAT EXPECTED TO CONTINUE FOR A FEW MORE HOURS.
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 26030.
...HALES
424,0965 425,0935 413,0935 412,0965SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 21, 7:37 PM CDT | Mesoscale Discussion | SPC | Audubon, Benton, Black Hawk, Boone, Bremer, Buchanan and 48 more | 83 min |
| May 22, 12:05 AM CDT | Severe Thunderstorm Watch | SPC | Benton, Black Hawk, Bremer, Buchanan, Butler, Cedar and 26 more | 6 hr |
| May 22, 12:25 AM CDT | Mesoscale Discussion | SPC | Audubon, Boone, Buena Vista, Calhoun, Carroll, Cherokee and 14 more | 2 hr |
| May 22, 12:55 AM CDT | Severe Thunderstorm Watch | SPC | Adair, Adams, Audubon, Boone, Carroll, Cass and 17 more | 5 hr |
| May 22, 2:41 AM CDT | Mesoscale Discussion | SPC | Benton, Black Hawk, Buchanan, Cedar, Clayton, Clinton and 24 more | 94 min |
| May 22, 3:44 AM CDT | Mesoscale Discussion | SPC | Adair, Adams, Audubon, Boone, Cass, Dallas and 11 more | 61 min |
| May 22, 6:58 AM CDT | Mesoscale Discussion | SPC | Appanoose, Davis, Decatur, Des Moines, Henry, Jefferson and 6 more | 62 min |
| May 22, 3:02 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Appanoose, Audubon, Cass, Clarke and 29 more | 58 min |
| May 22, 3:45 PM CDT | Tornado Watch | SPC | Fremont, Harrison, Mills, Pottawattamie, Shelby | 7 hr |
| May 22, 5:52 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Audubon, Benton, Black Hawk, Boone and 53 more | 113 min |
| May 22, 6:15 PM CDT | Tornado Watch | SPC | Adair, Adams, Appanoose, Audubon, Benton, Boone and 47 more | 6 hr |
| May 21, 7:40 PM CDT | Tornado Watch | SPC | Adams, Antelope, Boone, Boyd, Buffalo, Butler and 33 more | 5 hr |
| May 21, 10:01 PM CDT | Mesoscale Discussion | SPC | Adams, Antelope, Boone, Boyd, Buffalo, Butler and 33 more | 89 min |
| May 22, 1:13 PM CDT | Mesoscale Discussion | SPC | Banner, Chase, Cheyenne, Deuel, Dundy, Keith and 2 more | 2 hr |
| May 22, 2:00 PM CDT | Tornado Watch | SPC | Arthur, Banner, Chase, Cheyenne, Deuel, Dundy and 12 more | 6 hr |
| May 22, 3:04 PM CDT | Mesoscale Discussion | SPC | Banner, Chase, Cheyenne, Deuel, Dundy, Keith and 2 more | 86 min |
Nearby
Tornado Watches in Iowa, 2004Tornado Watches in Nebraska, 2004Every tornado watch in 2004
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.