Alert archive / Iowa / Severe Thunderstorm Warnings in 2020
Severe Thunderstorm Warning 170, NWS Des Moines, IA
NWS Des Moines, IA issued this severe thunderstorm warning at Oct 12, 2020, 2:11 AM CDT for 4 counties in Iowa. It was in force for 49 min. No storm report in the archive falls inside the area while it was in force.
The area
The outline as issued.
The facts
- Issued
- Oct 12, 2020, 2:11 AM CDT (07:11 UTC)
- Expired
- Oct 12, 2020, 3:00 AM CDT
- In force
- 49 min
- Issued by
- NWS Des Moines, IA
- Area
- Storm-based polygon
- Hail
- 0.75 in
- Wind
- 60.0 mph
Counties Cerro Gordo County, IA, Hancock County, IA, Winnebago County, IA, Worth County, IA
The radar
The Des Moines radar (KDMX), 160 km from the middle of the area, began a volume at 07:10 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.
Did it verify
Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm warning while it was in force. That is not proof nothing happened: reports are thin where few people live.
Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.
The nearest sounding before it
Minneapolis, MN (KMPX), launched 00:00Z, 7.2 hours before the alert went out and 190 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
- 54 J/kg
- Mixed-layer CIN
- -466 J/kg
- Mixed-layer LCL
- 1239 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 348 m²/s²
- 0-3 km storm-relative helicity
- 463 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
205 WUUS53 KDMX 120711 SVRDMX IAC033-081-189-195-120800- /O.NEW.KDMX.SV.W.0170.201012T0711Z-201012T0800Z/ BULLETIN - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Warning National Weather Service Des Moines, IA Issued by National Weather Service Quad Cities IA/IL 211 AM CDT Mon Oct 12 2020 The National Weather Service in Des Moines has issued a * Severe Thunderstorm Warning for... Worth County in north central Iowa... Hancock County in north central Iowa... Cerro Gordo County in north central Iowa... Winnebago County in north central Iowa... * Until 300 AM CDT. * At 210 AM CDT, severe thunderstorms were located along a line extending from near Bricelyn to 10 miles west of Belmond, moving east at 45 mph. HAZARD...65 mph wind gusts. SOURCE...ASOS reports at Mason City Airport. IMPACT...Expect damage to roofs, siding, and trees. * Locations impacted include... Mason City, Forest City, Garner, Northwood, Lake Mills, Britt, Manly, Rockwell, Emmons, Clear Lake, Eagle Lake, Mason City Municipal Airport, Rice Lake, Ventura, Kanawha, Klemme, Thompson, Thornton, Plymouth and Fertile. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a sturdy building. && LAT...LON 4291 9304 4291 9383 4350 9383 4350 9304 TIME...MOT...LOC 0710Z 262DEG 52KT 4350 9380 4290 9380 HAIL...<.75IN WIND...60MPH $$ rw
2 follow-up statements
451 WWUS53 KDMX 120739 SVSDMX Severe Weather Statement National Weather Service Des Moines, IA Issued by National Weather Service Quad Cities IA/IL 239 AM CDT Mon Oct 12 2020 IAC033-081-189-195-120800- /O.CON.KDMX.SV.W.0170.000000T0000Z-201012T0800Z/ Worth IA-Hancock IA-Cerro Gordo IA-Winnebago IA- 239 AM CDT Mon Oct 12 2020 ...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 300 AM CDT FOR WORTH...HANCOCK...CERRO GORDO AND WINNEBAGO COUNTIES... At 238 AM CDT, severe thunderstorms were located along a line extending from near Lake Mills to 8 miles west of Rockwell, moving east at 45 mph. HAZARD...60 mph wind gusts. SOURCE...Radar indicated. IMPACT...Expect damage to roofs, siding, and trees. Locations impacted include... Mason City, Forest City, Garner, Northwood, Lake Mills, Britt, Manly, Rockwell, Emmons, Clear Lake, Eagle Lake, Mason City Municipal Airport, Rice Lake, Ventura, Kanawha, Klemme, Thompson, Thornton, Plymouth and Fertile. LAT...LON 4291 9304 4291 9383 4350 9383 4350 9304 TIME...MOT...LOC 0738Z 260DEG 47KT 4345 9359 4296 9335 HAIL...<.75IN WIND...60MPH $$ rw
105
WWUS53 KDMX 120759
SVSDMX
Severe Weather Statement
National Weather Service Des Moines, IA
Issued by National Weather Service Quad Cities IA/IL
259 AM CDT Mon Oct 12 2020
IAC033-081-189-195-120807-
/O.EXP.KDMX.SV.W.0170.000000T0000Z-201012T0800Z/
Worth IA-Hancock IA-Cerro Gordo IA-Winnebago IA-
259 AM CDT Mon Oct 12 2020
...THE SEVERE THUNDERSTORM WARNING FOR WORTH...HANCOCK...CERRO GORDO
AND WINNEBAGO COUNTIES WILL EXPIRE AT 300 AM CDT...
The storms which prompted the warning have weakened below severe
limits, and no longer pose an immediate threat to life or property.
Therefore, the warning will be allowed to expire. However gusty
winds up to 45 mph are still possible with these thunderstorms.
LAT...LON 4291 9304 4291 9383 4350 9383 4350 9304
TIME...MOT...LOC 0757Z 262DEG 52KT 4349 9322 4300 9298
$$
rwWhat forecasters said that day
The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Des Moines, IA wrote its last area forecast discussion before this severe thunderstorm warning went out at Oct 12, 12:15 AM CDT, 1 hour 56 minutes earlier.
Area forecast discussion, Oct 12, 12:15 AM CDT, 1 hour 56 minutes before
AREA FORECAST DISCUSSION National Weather Service Des Moines IA Issued by National Weather Service Quad Cities IA IL 1215 AM CDT Mon Oct 12 2020 ...06Z AVIATION UPDATE... .Discussion... A rather wild ride from a very warm windy day today to a cooler pleasant day tomorrow is expected tonight. In the short term, the wind is certainly the story, as wind gusts continue to reach near advisory levels in the northwestern counties, while 15 to 25 mph are more common in the east. This wind will decrease with the loss of mixing depth by early evening/sunset, which will begin the reduction in the over all severe weather shear profile. Tonight, the cold front will arrive in the far west around 8 PM and exit far east around 4 AM. That will be the advertised severe weather time frame, but certainly the available DCAPE and low level shear interaction for any storm to interact with will be mainly in the far northwest with a general decay in storm intensity the farther east and late into the night we go. Thus, this is more of a "can't rule out" severe weather night, than one capable of becoming a widespread wind producer. Still, wind gusts to 40-50 mph see very much possible with evening storms, and overnight, some gusts to 45 mph still be possible, given the strong winds aloft. Rainfall tonight, should be in the quarter to half inch range for locations northwest of a Fort Dodge to Mason City line, and up to a quarter inch southeast of that axis. Looking at Monday through Wednesday, very pleasant conditions are expected with dry air, and highs reaching the upper 60s to mid 70s. A strong cold front will arrive late Wednesday, with a pattern change toward much cooler weather to finish the week. A deep and broad upper trof is forecast over the Great Lakes, with highs in the 50s, and lows in the upper 20s to mid 30s. This pattern is likely to bring a killing freeze to much of the Upper Midwest if they haven't seen it yet. ERVIN && .AVIATION...(For the 06Z TAFS through 06Z Monday Night) ISSUED AT 1210 AM CDT Mon Oct 12 2020 Predominantly VFR conditions through the period, with areas of MVFR/IFR overnight with precipitation along a cold front. Ongoing LLWS will abate overnight as a cold front moves through. Showers and storms along the front are expected to gradually diminish in both intensity and coverage while moving east/northeast overnight into early Monday. In the wake of the front, winds will become gusty from the northwest. Initially a 1-2 hour period of gusts 25-35 kts will be possible after the front moves through before tapering off into range of 10-20 kts. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && DISCUSSION...Ervin AVIATION...McClure
Hazardous weather outlook, Oct 12, 1:10 AM CDT, 1 hour 1 minute before
Hazardous Weather Outlook National Weather Service Des Moines IA Issued by National Weather Service Quad Cities IA IL 110 AM CDT Mon Oct 12 2020 IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075- 081>086-092>097-130615- Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo- Pocahontas-Humboldt-Wright-Franklin-Butler-Bremer-Sac-Calhoun- Webster-Hamilton-Hardin-Grundy-Black Hawk-Crawford-Carroll-Greene- Boone-Story-Marshall-Tama-Audubon-Guthrie-Dallas-Polk-Jasper- Poweshiek-Cass-Adair-Madison-Warren-Marion-Mahaska-Adams-Union- Clarke-Lucas-Monroe-Wapello-Taylor-Ringgold-Decatur-Wayne- Appanoose-Davis- 110 AM CDT Mon Oct 12 2020 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Overnight Isolated thunderstorms are possible. Lightning and gusty winds are the primary threats. Northwest winds will gust 30 to 40 mph for a few hours in the wake of a cold frontal passage. .DAYS TWO THROUGH SEVEN...Monday through Saturday The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
In the hours before
Special weather statement, Oct 12, 12:21 AM CDT, 1 hour 50 minutes before
Special Weather Statement National Weather Service Des Moines, IA Issued by National Weather Service Quad Cities IA/IL 1221 AM CDT Mon Oct 12 2020 IAC015-049-099-121-125-127-153-169-181-120615- Polk-Story-Marshall-Madison-Marion-Jasper-Boone-Dallas-Warren- 1221 AM CDT Mon Oct 12 2020 ...A LINE OF STRONG THUNDERSTORMS WILL AFFECT POLK...STORY...WESTERN MARSHALL...NORTHEASTERN MADISON...NORTHWESTERN MARION...WESTERN JASPER...EASTERN BOONE...EASTERN DALLAS AND WARREN COUNTIES UNTIL 115 AM CDT... At 1220 AM CDT, radar indicated strong thunderstorms were located along a line extending from 11 miles north of Boone to near Winterset. Movement was east at 45 mph. Wind gusts up to 50 mph are possible with these storms. Locations impacted include... Des Moines, Ames, West Des Moines, Ankeny, Urbandale, Johnston, Clive, Indianola, Altoona, Waukee, Boone, Norwalk, Pleasant Hill, Grimes, Nevada, Winterset, Adel, Windsor Heights, Carlisle and Bondurant. If outdoors, consider seeking shelter inside a building. LAT...LON 4220 9319 4128 9318 4130 9400 4221 9396 TIME...MOT...LOC 0520Z 267DEG 35KT 4221 9394 4131 9393 rw
Local storm report, Oct 12, 12:31 AM CDT, 1 hour 40 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1231 AM CDT MON OCT 12 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1210 AM TSTM WND GST BEDFORD 40.67N 94.72W
10/12/2020 M61 MPH TAYLOR IA MESONET
RWIS.
&&Local storm report, Oct 12, 12:37 AM CDT, 1 hour 34 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1237 AM CDT MON OCT 12 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1207 AM TSTM WND GST ADEL 41.61N 94.03W
10/12/2020 M50 MPH DALLAS IA TRAINED SPOTTER
&&Special weather statement, Oct 12, 12:46 AM CDT, 1 hour 25 minutes before
Special Weather Statement National Weather Service Des Moines, IA Issued by National Weather Service Quad Cities IA/IL 1246 AM CDT Mon Oct 12 2020 IAC039-053-117-121-125-159-175-181-185-120630- Lucas-Decatur-Madison-Union-Marion-Wayne-Ringgold-Clarke-Warren- 1246 AM CDT Mon Oct 12 2020 ...A LINE OF SHOWERS WILL AFFECT WESTERN LUCAS...DECATUR... SOUTHEASTERN MADISON...EASTERN UNION...SOUTHWESTERN MARION...WESTERN WAYNE...EASTERN RINGGOLD...CLARKE AND SOUTHERN WARREN COUNTIES UNTIL 130 AM CDT... At 1246 AM CDT, radar indicated showers were located along a line extending from 8 miles southeast of Avenue Of The Saints Event Center to near Lamoni. Movement was east at 45 mph. Wind gusts up to 50 mph are possible with these showers. Locations impacted include... Osceola, Chariton, Leon, Lamoni, Melcher-Dallas, Sun Valley Lake, Lakeside Casino, Avenue Of The Saints Event Center, Milo, Murray, St. Charles, Humeston, New Virginia, Truro, Lacona, Kellerton, Grand River, Van Wert, Lineville and Lucas. LAT...LON 4131 9397 4128 9317 4058 9349 4057 9424 TIME...MOT...LOC 0546Z 268DEG 40KT 4124 9364 4056 9396 Uttech
Special weather statement, Oct 12, 1:31 AM CDT, 40 minutes before
Special Weather Statement National Weather Service Des Moines, IA Issued by National Weather Service Quad Cities IA/IL 131 AM CDT Mon Oct 12 2020 IAC033-069-079-081-083-197-120730- Hardin-Wright-Franklin-Hancock-Hamilton-Cerro Gordo- 131 AM CDT Mon Oct 12 2020 ...A LINE OF STRONG THUNDERSTORMS WILL AFFECT HARDIN...EASTERN WRIGHT...FRANKLIN...EASTERN HANCOCK...EASTERN HAMILTON AND CERRO GORDO COUNTIES UNTIL 230 AM CDT... At 130 AM CDT, radar indicated strong thunderstorms were located along a line extending from near Forest City to near Jewell Junction. Movement was east at 40 mph. Wind gusts up to 50 mph are possible with these storms. Locations impacted include... Mason City, Iowa Falls, Hampton, Forest City, Garner, Eldora, Belmond, Ackley, Nora Springs, Jewell Junction, Sheffield, Rockwell, Elm Lake, Clear Lake, Big Wall Lake, Mason City Municipal Airport, Hubbard, Alden, Ventura and Radcliffe. If outdoors, consider seeking shelter inside a building. LAT...LON 4325 9303 4221 9302 4222 9370 4325 9369 TIME...MOT...LOC 0630Z 251DEG 21KT 4322 9367 4233 9369 rw
Local storm report, Oct 12, 2:04 AM CDT, 7 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
204 AM CDT MON OCT 12 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0151 AM TSTM WND GST 3 NE CLEAR LAKE 43.16N 93.33W
10/12/2020 M63 MPH CERRO GORDO IA ASOS
&&
RWThe office that day
Everything else NWS Des Moines, IA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 11, 11:01 PM CDT | Severe Thunderstorm Warning | DMX | Adair, Adams, Cass, Taylor | 59 min |
| Oct 11, 11:52 PM CDT | Severe Thunderstorm Warning | DMX | Adair, Clarke, Decatur, Madison, Ringgold, Union and 1 more | 53 min |
| Oct 12, 12:00 AM CDT | Severe Thunderstorm Warning | DMX | Adams, Taylor | 15 min |
| Oct 12, 12:12 AM CDT | Special Weather Statement | DMX | Calhoun, Carroll, Greene, Humboldt, Pocahontas, Webster | 48 min |
| Oct 12, 12:21 AM CDT | Special Weather Statement | DMX | Boone, Polk, Story, Warren | 54 min |
| Oct 12, 12:46 AM CDT | Special Weather Statement | DMX | Clarke, Decatur, Lucas | 44 min |
| Oct 12, 1:31 AM CDT | Special Weather Statement | DMX | Cerro Gordo, Franklin, Hardin | 59 min |
Nearby
Severe Thunderstorm Warnings in Iowa, 2020Every severe thunderstorm warning in 2020
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.