Ice Storm — Woodbury, Iowa

2020-11-09 to 2020-11-10 · Woodbury, Iowa

Event narrative

Freezing rain overnight and through the morning resulted in ice accumulation of a quarter to half inch, especially on elevated surfaces, including powerlines. Brief power outages were reported. Snowfall developed later morning and through the afternoon, and accumulated to 3.0 inches at Sioux City. Slick roadways resulted in several accidents. An (indirect) fatality occurred on eastbound U.S. Highway 20 west of Moville shortly after 1200CST, when the driver and sole occupant of the vehicle left the road and rolled several times. Around the onset time of the freezing rain during the evening of November 9, more than 200 ducks were killed when they confused wet and ice-covered Highway 20 for wetlands and were hit by passing vehicles. Property damage costs are rough estimates.

Wider weather episode

Unusual warmth with a week of temperatures mainly in the 70s (even 50s and 60s on November 9 less than a day before this storm) was brought to an abrupt end as a deep trough of low pressure moved out of Rockies and into the Plains. An intense lower- to mid-level frontal zone oozed eastward as a strong jet lifted out across the Plains on November 10, initiating widespread precipitation. More rapid shallow cooling occurred across northwest Iowa and led to a swath of freezing rain which accumulated from a tenth to a half inch during the overnight and morning hours, before changing to snow in the afternoon. Heavier and more persistent snowfall occurred with the deeper cooling to the northwest across southeast South Dakota, far northwest Iowa and southwest Minnesota, where amounts ranged from 3 to 7 inches.

Source: NOAA Storm Events Database, event_id 928567. Narrative written by the NWS forecast office that issued the report.