A mid-level disturbance worked northeast from Colorado early morning January 12 into Iowa by late day. Broad lift initially within the warm advection zone became increasingly concentrated, with deeper lift in the dendritic growth layer by afternoon across northwest Iowa.
Every event with a place to put it; 7 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.
A mid-level disturbance worked northeast from Colorado early morning January 12 into Iowa by late day. Broad lift initially within the warm advection zone became increasingly concentrated, with deeper lift in the dendritic growth layer by afternoon across northwest Iowa. Snowfall rates up to 1.5 to 2 inches per hour were noted across northwest Iowa and northeast Nebraska at the peak during the late afternoon.
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 12, 5:31 AM CST, 3 hours 29 minutes earlier.
AREA FORECAST DISCUSSION National Weather Service Sioux Falls SD 531 AM CST Sun Jan 12 2020 .SHORT TERM...(Today and Tonight) Issued at 350 AM CST Sun Jan 12 2020 Focus for today will be on wave lifting out of southeast Colorado early this morning. This wave still slated to track northeast toward western Iowa by mid-late afternoon. Broad, but weak lift ahead of the wave should bring some light snow to our southern counties by mid-late morning, though exact timing of development will depend on how quickly sub-10kft layer saturates, as lift will initially be on the weak side. This should change by midday/early afternoon as the wave reaches eastern Nebraska. From 18Z-21Z, should see increasing mid-level lift, coincident with dendritic snow-growth zone in some parts of northwest IA/southwest MN. This should allow for increase in snowfall rates during the afternoon/early evening, primarily along and east of the Highway 60 corridor, with a quick 1-2+ inches likely during this window. After 03Z, wave and associated lift move east of the forecast area, and will see snow quickly diminish from west to east through the mid evening hours. Just how far northwest the area of snow will spread is still in question, with KYKN-KFSD-KMML line very likely near the northwest edge of accumulating snow. These areas should almost certainly see less than an inch, and more likely around a half inch or less. As far as temperatures, should see readings climb closer to normal today, but still falling a few degrees shy most areas with highs generally in the upper teens to mid 20s expected. Very little drop expected through the overnight hours, with modest southerly flow and slow-to-clear cloud cover holding up readings. .LONG TERM...(Monday through Saturday) Issued at 350 AM CST Sun Jan 12 2020 The work week will start on a mild note, temperatures Monday still expected to climb into the upper 20s-mid 30s. This will not last long, however, as a couple of ripples in the upper flow will bring repeated shots at modest cooling through midweek. These will also bring some additional light snow chances, the first impacting our far eastern, and perhaps far northern areas Monday night. The next may bring a little more widespread light snow Tuesday night into Wednesday, but models are showing less agreement with this wave, so while confidence is rather high that accumulations will be light, confidence lower on timing/location. Temperatures in the wake of this wave likely to be the coolest of the work week, with at least northern parts of the area seeing their next shot at sub-zero low temperatures Wednesday night. Upper flow becoming more amplified for the latter part of the week, with ridge building over the Upper Midwest Thursday as deeper trough moves onto the West Coast. This should keep Wednesday night-Thursday dry, but temperatures slow to recover from the cool Wednesday night readings, so still expecting below normal high temperatures Thursday despite strong push of warm air aloft beneath the building upper ridge. Late week will see the upper ridge shift east, with the West Coast trough working across the Rockies and into the Plains. Plenty of uncertainty with this system, but in general could be looking at more moisture, as well as potential for mixed precipitation types, so bears keeping an eye on as we move through the week. && .AVIATION...(For the 12Z TAFS through 12Z Monday morning) Issued at 531 AM CST Sun Jan 12 2020 Deteriorating conditions expected across the southeast half of the region, near and especially southeast of a KYKN-KFSD-KMML line, from late morning into the early evening. MVFR-IFR conditions will become likely as snow spreads across the area. Even after the snow moves east of the area after 13/03Z, low end MVFR-IFR or lower stratus, and possibly fog, will persist. At this time, extent of fog is uncertain, so have not included the reduced visibility in TAFs after 13/01Z at this time. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && SHORT TERM...JH LONG TERM...JH AVIATION...JH
Hazardous Weather Outlook National Weather Service Sioux Falls SD 504 AM CST Sun Jan 12 2020 IAZ001>003-012>014-020>022-031-032-MNZ080-081-089-090-098-NEZ013-014- SDZ067-070-071-131115- Lyon-Osceola-Dickinson-Sioux-O'Brien-Clay-Plymouth-Cherokee- Buena Vista-Woodbury-Ida-Murray-Cottonwood-Nobles-Jackson-Rock-Dixon- Dakota-Lincoln-Union- 504 AM CST Sun Jan 12 2020 This Hazardous Weather Outlook is for northwest Iowa, west central Iowa, southwest Minnesota, northeast Nebraska and southeast South Dakota. .DAY ONE...Today and tonight. Light snow will spread across the area from mid morning through early evening, with accumulations from 1 to 3 inches expected. .DAYS TWO THROUGH SEVEN...Monday through Saturday. While there will be multiple chances for snow Monday night through Wednesday, any accumulation will light. Late week could bring another round of precipitation to the region, and while snow is most likely, a wintry mix is possible in some areas. Details on this system are still uncertain, and will be refined as the week progresses. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. MNZ071-072-097-SDZ038>040-050-052>066-068-069-131115- Lincoln-Lyon-Pipestone-Beadle-Kingsbury-Brookings-Gregory-Jerauld- Sanborn-Miner-Lake-Moody-Brule-Aurora-Davison-Hanson-McCook- Minnehaha-Charles Mix-Douglas-Hutchinson-Turner-Bon Homme-Yankton- 504 AM CST Sun Jan 12 2020 This Hazardous Weather Outlook is for southwest Minnesota, central South Dakota, east central South Dakota, south central South Dakota and southeast South Dakota. .DAY ONE...Today and tonight. There is a chance of light snow across far southeast South Dakota and southwest Minnesota today into early this evening. Any accumulation is expected to remain less than an inch, with higher amounts likely southeast of a line from Yankton, to Sioux Falls, to Marshall. .DAYS TWO THROUGH SEVEN...Monday through Saturday. Areas of light snow will move across the area Tuesday night into Wednesday. Late week could bring another round of precipitation to the region, and while snow is most likely, a wintry mix is possible in some areas. Details on this system are still uncertain, and will be refined as the week progresses. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The national radar mosaic for the moment the first event began.
6 winter weather, 1 winter storm. Local standard time, as filed.
Initially light snowfall became heavy at times during the afternoon and early evening hours. Intense snowfall rates resulted in a rapid worsening of road conditions. Accumulation reached 7.0 inches at Orange City, 6.5 inches at Alton and 4.0 inches at Sioux Center.
Snowfall was briefly moderate to heavy during the afternoon and early evening, accumulating to 4.5 inches 3 miles west northwest of Everly, 4.0 inches at Peterson and 3.9 inches at Spencer, resulting in dangerous travel conditions.
Snowfall was briefly moderate to heavy during the afternoon and early evening, accumulating to 5.3 inches at Hartley, 5.0 inches at Sanborn, 4.7 inches at Primghar and 3.6 inches at Sheldon, resulting in dangerous travel conditions. Poor road conditions lingered after the snowfall due to continued drifting snow with increased southerly winds. On January 13 around 1620CST, a vehicle lost control attempting to pass another on U.S. Highway 18 around 2 miles east of Sanborn, entered the ditch and rolled, resulting in an (indirect) injury to the driver. A second accident around 0900CST the following day and in approximately the same location resulted in a rollover in the ditch and another (indirect) injury. Property damage costs are rough estimates.
Snowfall was briefly moderate to heavy during the afternoon, accumulating to 3.0 inches at Rock Rapids, resulting in dangerous travel conditions.
Snowfall was briefly moderate to heavy during the afternoon and early evening, accumulating to 3.5 inches at Sibley, resulting in dangerous travel conditions.
Snowfall was briefly moderate to heavy during the afternoon and early evening, accumulating to 4.4 inches 4 miles northwest of Milford, 4.1 inches at Spirit Lake, 4.0 inches at Milford and 3.1 inches at Lake Park, resulting in dangerous travel conditions.
Snowfall was briefly moderate to heavy during the afternoon, accumulating to 3.5 inches at Le Mars and 3.0 inches at Brunsville and Akron, resulting in dangerous travel conditions. Following this snowfall, slick road conditions which lingered due to drifting snow during the early morning of January 14 resulted in a pair of (indirect) fatalities in a two-vehicle accident on County Road K22 near Granite Avenue.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| Winter Weather, Plymouth | 2020-01-14 | Male | Vehicle/Towed Trailer | Indirect | |
| Winter Weather, Plymouth | 2020-01-14 | Female | Vehicle/Towed Trailer | Indirect |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2020Every state in 2020This day in weather historyWarnings in Iowa, January 2020
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: 873918, 873928, 873930, 873922, 873923, 873926, 873932.