Precipitation varied from 50 to 75 percent of normal in far northwest Iowa, to slightly above normal precipitation east of a line from Sioux City to Spencer.
Every event with a place to put it; 11 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 FSD wrote it up.
Precipitation varied from 50 to 75 percent of normal in far northwest Iowa, to slightly above normal precipitation east of a line from Sioux City to Spencer.
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 Sioux Falls, SD wrote its last area forecast discussion before the first event at Jan 31, 10:24 PM CST, 1 hour 36 minutes earlier.
AREA FORECAST DISCUSSION National Weather Service Sioux Falls SD 1024 PM CST Sun Jan 31 2021 .SHORT TERM...(This Evening through Monday) Issued at 208 PM CST Sun Jan 31 2021 Persistent stratus and its impact on temperatures will be the main challenge in the short term. While there are a few breaks here and there, stratus is still fairly widespread across the eastern Dakotas and Minnesota, with the clearing line near, but still west of the Missouri River in the mid afternoon. Cloud layer trajectories remain from the north tonight, with surface winds becoming light/variable overnight as a surface ridge moves into the forecast area. Stratus may thin at times, but soundings show this moist layer just becomes trapped beneath strengthening subsidence inversion with approaching surface ridge tonight, so opting toward pessimistic persistence tonight into at least mid morning on Monday. The expected cloud cover should favor low temperatures on the warmer side of guidance, largely in the mid to upper teens. Warming Monday will also be tempered by the morning clouds, though areas that do finally break out of the stratus will have a potential for greater warming. Will hold somewhat conservative for now, with highs from the mid-upper 20s along/east of I-29, to mid 30s in south central SD. .LONG TERM...(Monday Night through Sunday) Issued at 208 PM CST Sun Jan 31 2021 Dry and mild weather will dominate the first half of the upcoming week, as upper ridge builds across the Plains behind slow-moving East Coast storm system. Low level winds swing around to the south behind departing surface ridge late Monday/Monday night, and some models hint that this could bring low stratus back into the region, beneath strengthening inversion aloft. Confidence in this returning by early Tuesday is low, so will stick with partly cloudy skies and a modest warming on Tuesday. Stronger warming projected across the region Wednesday, but again will have to consider impact of cloud cover, whether from potential stratus, or an increase in mid-high clouds ahead of a subtle wave sliding across the northern Plains on Wednesday. Will keep forecast highs close to the middle of the pack for now, but 75th-90th percentiles of the NBM portray potential for more significant warming, especially in areas west of I-29. Wednesday night-Thursday will bring our next chance of light precip, as northern stream wave digs into the northern Plains/western Great Lakes. Deterministic global models still favor precipitation amounts remaining on the lighter side, primarily snow as the cold air builds southeast late Wednesday night/Thursday. Still a few members of GEFS and ECMWF ensembles that remain a bit more burly with precipitation output, so will continue to monitor trends, but vast majority are clustered toward lighter deterministic amounts across our forecast area. That said, timing differences preclude raising pops beyond lower chance range for now. Cannot rule out some mixed precip types on the leading edge, before warmer air is pushed out of the area, but too much uncertainty to carry anything more than rain/snow mix at this time. The above system will be followed by the first surge of colder air into the north central CONUS, potentially leading to falling temps through the day Thursday, accompanied by gusty northwest winds. The winds and chances for light snow could still result in minor travel impacts Thursday, even with expected light snowfall amounts, and may need to begin highlighting this in the coming days if confidence in potential snow accumulations increases. Models diverge on details for next weekend, but broad consensus that a reinforcing shot of colder air will be pushing southward into the region through the first half of next weekend, as a trailing wave and associated arctic cold front swing south around an upper low wobbling over eastern Canada. While there is a wide spread between the extremes of ensemble solutions (in the neighborhood of 40F or more top to bottom for highs Sunday), mean temperature anomalies from both GEFS and ECMWF ensembles are running anywhere from 15F to 30F below normal this weekend. Not a slam dunk, but seems like a decent potential that some areas will be seeing the coldest air of this winter season settling in for at least a brief stay this coming weekend. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 1023 PM CST Sun Jan 31 2021 Latest satellite imagery continues to show pesky stratus deck blanketing the region, causing cigs at all TAF sites to hover around IFR levels, which is expected to continue throughout the overnight period. Could even see some brief periods of LIFR, however, confidence on this remains somewhat lower, so will continue to monitor trends in the coming hours and adjust as necessary. Unfortunately, cigs will be slow to lift after daybreak as light winds limit mixing. As a result, expect MVFR cigs to gradually return during the afternoon hours, with VFR levels forecast to return tomorrow afternoon. Otherwise, expect dry conditions and light and variable winds to prevail throughout the period. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && SHORT TERM...JH LONG TERM...JH AVIATION...SSC
Hazardous Weather Outlook National Weather Service Sioux Falls SD 410 AM CST Sun Jan 31 2021 IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097- 098-NEZ013-014-SDZ038>040-050-052>071-011015- Lyon-Osceola-Dickinson-Sioux-O'Brien-Clay-Plymouth-Cherokee- Buena Vista-Woodbury-Ida-Lincoln-Murray-Cottonwood-Nobles-Jackson- Pipestone-Rock-Dixon-Dakota-Beadle-Kingsbury-Brookings-Gregory- Jerauld-Sanborn-Miner-Lake-Moody-Brule-Aurora-Davison-Hanson-McCook- Minnehaha-Charles Mix-Douglas-Hutchinson-Turner-Bon Homme-Yankton- Union- 410 AM CST Sun Jan 31 2021 This Hazardous Weather Outlook is for northwest Iowa, west central Iowa, southwest Minnesota, northeast Nebraska, central South Dakota, east central South Dakota, south central South Dakota and southeast South Dakota. .DAY ONE...Today and tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Monday through Saturday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The national radar mosaic for the moment the first event began.
11 drought. Local standard time, as filed.
Extreme (D3) drought conditions for most of February showed a slight improvement to Severe (D2) at the end of the month.
Extreme (D3) drought conditions continued through February.
Extreme (D3) drought conditions continued through February.
Severe (D2) drought conditions continued through February.
Severe (D2) drought conditions for most of February showed minor improvement to moderate (D1) at the end of the month.
Extreme (D3) drought conditions continued through February.
Extreme (D3) drought conditions continued through February.
Extreme (D3) drought conditions continued through February.
Extreme (D3) drought conditions continued through February.
Extreme (D3) drought conditions continued through February.
Severe (D2) drought conditions continued through February.
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, February 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: 939442, 939443, 939444, 939446, 939448, 939450, 939451, 939452, 939453, 939454, 939455.