Alert archive / Iowa / Tornado Watches in 2004
Tornado Watch 869
The Storm Prediction Center issued this tornado watch at Oct 29, 2004, 2:50 PM CDT for 52 counties in Iowa. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Oct 29, 2004, 2:50 PM CDT (19:50 UTC)
- Expired
- Oct 29, 2004, 9:00 PM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
All 52 counties
Adair County, IA, Adams County, IA, Appanoose County, IA, Audubon County, IA, Black Hawk County, IA, Boone County, IA, Bremer County, IA, Butler County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Cerro Gordo County, IA, Chickasaw County, IA, Clarke County, IA, Dallas County, IA, Decatur County, IA, Emmet County, IA, Floyd County, IA, Franklin County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Howard County, IA, Humboldt County, IA, Jasper County, IA, Kossuth County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Mitchell County, IA, Monroe County, IA, Page County, IA, Palo Alto County, IA, Pocahontas County, IA, Polk County, IA, Poweshiek County, IA, Ringgold County, IA, Story County, IA, Tama County, IA, Taylor County, IA, Union County, IA, Warren County, IA, Wayne County, IA, Webster County, IA, Winnebago County, IA, Worth County, IA, Wright County, IA
The radar
The Des Moines radar (KDMX), 21 km from the middle of the area, began a volume at 19:51 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
11 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 29, 5:10 PM CDT | Tornado Warning | DMX | Decatur | 35 min |
| Oct 29, 5:21 PM CDT | Tornado Warning | DMX | Clarke | 39 min |
| Oct 29, 5:40 PM CDT | Severe Thunderstorm Warning | DMX | Lucas, Warren | 35 min |
| Oct 29, 5:43 PM CDT | Severe Thunderstorm Warning | DMX | Story | 17 min |
| Oct 29, 5:57 PM CDT | Severe Thunderstorm Warning | DMX | Marion | 33 min |
| Oct 29, 5:59 PM CDT | Severe Thunderstorm Warning | DMX | Hardin | 16 min |
| Oct 29, 6:27 PM CDT | Severe Thunderstorm Warning | DMX | Jasper, Poweshiek | 33 min |
| Oct 29, 6:36 PM CDT | Severe Thunderstorm Warning | ARX | Mitchell | 39 min |
| Oct 29, 7:04 PM CDT | Severe Thunderstorm Warning | ARX | Howard | 26 min |
| Oct 29, 7:37 PM CDT | Severe Thunderstorm Warning | DMX | Butler | 23 min |
| Oct 29, 7:54 PM CDT | Severe Thunderstorm Warning | DMX | Marshall, Tama | 36 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
Omaha, NE (KOAX), launched 12:00Z, 7.8 hours before the alert went out and 205 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
- 1500 J/kg
- Mixed-layer CIN
- -51 J/kg
- Mixed-layer LCL
- 695 m above ground
- 0-6 km bulk shear
- 35 kt
- 0-1 km storm-relative helicity
- 227 m²/s²
- 0-3 km storm-relative helicity
- 222 m²/s²
- Significant tornado parameter
- 1.2
- Supercell composite
- 7.8
The text
As transmitted, in the capitals the NWS used until 2016.
000
WWUS20 KWNS 291948
SEL9
SPC WW 291950
IAZ000-300200-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 869
NWS STORM PREDICTION CENTER NORMAN OK
250 PM CDT FRI OCT 29 2004
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
CENTRAL IOWA
EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 250 PM UNTIL 900
PM CDT.
TORNADOES...HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.
THE TORNADO WATCH AREA IS ALONG AND 70 STATUTE MILES EAST AND WEST
OF A LINE FROM 25 MILES NORTH NORTHWEST OF MASON CITY IOWA TO 5
MILES EAST SOUTHEAST OF LAMONI 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.
DISCUSSION...BAND OF CONVECTION ALONG/AHEAD OF SURFACE COLD FRONT IS
EXPECTED TO INTENSIFY DURING THE NEXT FEW HOURS AS IT TRACKS ACROSS
IA. MODERATE INSTABILITY AND APPROACH OF IMPRESSIVE UPPER TROUGH
WILL RESULT IN SCATTERED STRONG/SEVERE THUNDERSTORMS. 80-100 KNOT
MID LEVEL WINDS AND LINEAR NATURE OF STORMS WILL ENHANCE THE RISK OF
DAMAGING WINDS. VERY STRONG LOW LEVEL SHEAR MAY ALSO BE SUFFICIENT
FOR ISOLATED TORNADOES.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 24045.
...HART
432,0920 403,0923 403,0951 432,0945SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 29, 2:12 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Audubon, Boone, Buena Vista, Butler and 46 more | 3 hr |
| Oct 29, 3:35 PM CDT | Tornado Watch | SPC | Emmet, Winnebago, Worth | 5 hr |
| Oct 29, 5:24 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Appanoose, Boone, Bremer, Butler and 33 more | 96 min |
| Oct 29, 5:46 PM CDT | Mesoscale Discussion | SPC | Allamakee, Benton, Buchanan, Cedar, Clayton, Clinton and 18 more | 89 min |
| Oct 29, 6:30 PM CDT | Tornado Watch | SPC | Allamakee, Benton, Buchanan, Cedar, Clayton, Clinton and 19 more | 6 hr |
Nearby
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.