A cold front moved across the state overnight through the early morning hours of November 11th. Strong subsidence and dry air resulted in extremely deep mixing in the boundary layer.
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS DMX wrote it up.
A cold front moved across the state overnight through the early morning hours of November 11th. Strong subsidence and dry air resulted in extremely deep mixing in the boundary layer. Winds across the state gusted up to 50 mph with a single report from a personal weather station of a gust of 60 mph.
The local office's own words before the first event, 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 the first event at Nov 11, 6:02 PM CST, 13 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 602 PM CST Thu Nov 11 2021 ...Updated for the 00z Aviation Discussion... .DISCUSSION.../Tonight through Thursday/ Issued at 331 PM CST Thu Nov 11 2021 Key Messages: - Accumulating light snow expected over parts of northern Iowa tonight into early Friday. - Strong and gusty winds for much of the area tonight and Friday - More light snow over northern Iowa Saturday night/early Sunday Surface low pressure continues to deepen and retrograde back to the northwest over the Minnesota Arrowhead this afternoon as a vigorous upper low settles southeast into southern Minnesota this afternoon. The upper low has several strong impulses rotating around the system tonight and into Friday. One impulse will arrive overnight into early Friday and is expected to bring a broad area of light snow into parts of northern Iowa with some accumulations likely. Current road surface temperatures are in the upper 40s to low 50s however, with the cold advection arriving overnight along with snow helping to cool the surface, road temperatures are expected to drop into the low 30s by late tonight and persist into early Friday morning before some solar radiation penetrating through the clouds helps warm them a bit. Therefore, slick road conditions are certainly possible. The initial snow will have at least some dendritic potential with forcing through the dendritic layer. Mid-level drying with the passing of the upper level impulse will result in a gradually more shallow saturated layer below 700 mb. While vertical ascent will persist in this saturated layer, the very top of the saturated layer will be just skimming the preferred ice introduction temperature zone so it is possible that ice introduction is lost and a period of drizzle occurs from late morning and into the afternoon. In addition, the differential cold advection during this period will lead to a well mixed boundary layer that will help maximize momentum transfer of mixed layer winds to the surface. Wind gusts in excess of 50 mph are certainly possible. Have maintained the current Winter Weather Advisory area but adjusted the timing up to 03z this evening. The Wind Advisory has been expanded south to near Indianola and west to Atlantic. Additional expansions to headlines are likely with the flavor pending the evolution of the light snow potential. As alluded to the past few days, enough instability will be available for convective snow showers to develop over mainly northern Iowa. These could have headline impacts as well. The precipitation is expected to end quickly from west to east by late afternoon Friday though the gusty winds will persist into the evening. Saturday will remain cool as the upper low departs to the northeast. Another strong short wave will arrive late Saturday and Saturday night in the form of a clipper type surface low. This system is expected to produce a band of light snow along the northern periphery of the surface low with some very light rain or snow to the south. At this time, the track of any accumulating snow potential for Saturday night and into early Sunday remains over far northern Iowa and into Minnesota. There are some hints that another band of precipitation could form along a baroclinic zone over far southern Iowa and into Missouri and Nebraska. Should that band develop, the precipitation type is expected to remain rain and cause little to no impacts. The system will also bring another round of strong and gusty winds to the state. Stay tuned in case any headlines are needed. A transition from northwest to more westerly/zonal flow will occur next Monday and Tuesday and will result in a brief warming trend before more cold air arrives towards Wednesday. High temperatures will peak in the 50s to low 60s on Tuesday before another cold front passes through the state and drops temperatures again for the rest of the forecast period. Some light precipitation may accompany the boundary passage, otherwise, no significant weather for the extended period. && .AVIATION.../For the 00Z TAFS through 00Z Friday evening/ Issued at 559 PM CST Thu Nov 11 2021 MVFR stratus was just getting into the NW forecast area near KEST at 00z with VFR conditions elsewhere. Scattered light rain showers were occurring in these higher based clouds, and with low relative humidities beneath, some of it was reaching the ground as graupel due to evaporative cooling so will mention -RASN for the next several hours before temps cool further and snow becomes more prominent north with light rain or a mix expanding south with MVFR expected down to KDSM by early Fri morning. Winds will remain strong and gusty otherwise with gusts well through the 30s /kts/ by tomorrow and 40+ possible at times. && .DMX WATCHES/WARNINGS/ADVISORIES... Wind Advisory from 9 PM this evening to 6 PM CST Friday for IAZ023-024-033>037-044>048-057>060-070>073. Winter Weather Advisory from 9 PM this evening to 3 PM CST Friday for IAZ004>007-015>017-025-026. && DISCUSSION...Donavon AVIATION...Small
Hazardous Weather Outlook National Weather Service Des Moines IA 254 PM CST Thu Nov 11 2021 IAZ027-028-038-039-049-050-061-062-074-075-081>086-092>097-122100- Butler-Bremer-Grundy-Black Hawk-Marshall-Tama-Jasper-Poweshiek- Marion-Mahaska-Adams-Union-Clarke-Lucas-Monroe-Wapello-Taylor- Ringgold-Decatur-Wayne-Appanoose-Davis- 254 PM CST Thu Nov 11 2021 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...This afternoon and tonight Gusty winds, gusting to around 40 mph at times, will continue through tonight across the area. Light snow will begin to move into portions of northern and central Iowa tonight, with light accumulations expected around and north of Highway 30. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Light snow will continue to move across the area Friday, including accumulations to around an inch across northern Iowa, under an inch into central Iowa, and a possible dusting across southern Iowa. Accumulations will be most likely on grassy and elevated surfaces. Winds too will remain strong out of the NW, with sustained speeds in excess of 30 mph and gusts to 45 mph likely at times. Strongest winds will be over western Iowa. .SPOTTER INFORMATION STATEMENT... Spotters will not be needed, but snowfall reports are always appreciated. IAZ023-024-033>037-044>048-057>060-070>073-122100- Pocahontas-Humboldt-Sac-Calhoun-Webster-Hamilton-Hardin-Crawford- Carroll-Greene-Boone-Story-Audubon-Guthrie-Dallas-Polk-Cass-Adair- Madison-Warren- 254 PM CST Thu Nov 11 2021 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...This afternoon and tonight A Wind Advisory is in effect for the area beginning late tonight. Please refer to the National Weather Service website at weather.gov/desmoines for further details. Light snow and light accumulations will overspread the area tonight, continuing into Friday. Combined with strong winds, visibilities and general travel may be hazardous at times. .DAYS TWO THROUGH SEVEN...Friday through Wednesday A Wind Advisory is in effect for the area through Friday afternoon. Please refer to the National Weather Service website at weather.gov/desmoines for further details. Light snow will continue into Friday afternoon. Combined with strong winds, visibilities and general travel may be hazardous at times. Accumulations under an inch are expected, with greatest amounts on elevated and grassy surfaces. .SPOTTER INFORMATION STATEMENT... Spotters will not be needed, but snowfall reports are always appreciated. IAZ004>007-015>017-025-026-122100- Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo- Wright-Franklin- 254 PM CST Thu Nov 11 2021 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...This afternoon and tonight A Winter Weather Advisory is in effect for the area beginning late tonight. Please refer to the National Weather Service website at weather.gov/desmoines for further details. .DAYS TWO THROUGH SEVEN...Friday through Wednesday A Winter Weather Advisory is in effect for the area through Friday afternoon. Please refer to the National Weather Service website at weather.gov/desmoines for further details. .SPOTTER INFORMATION STATEMENT... Spotters will not be needed, but snowfall reports are always appreciated. CURTIS
The national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
Spotter relayed a 60.3 mph wind gust on a personal weather station. Additionally, reported multiple tree limbs down, the largest of which was seven inches in diameter from a healthy tree.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2021Every state in 2021This day in weather historyWarnings in Iowa, November 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 987605.