Blizzard — Wright, Iowa

2012-12-20 · Wright, Iowa

Wider weather episode

Part 2 of 2: The seasons first major winter storm moved into Iowa during the late afternoon and evening of the 19th and continued into the day on the 20th and became a blizzard for much of the Des Moines CWA. A strong low pressure developed over southeast Colorado and pushed east across southern Kansas. The low turned northeast through Missouri and into southern Lake Michigan by the 20th. As the low moved into Lower Michigan the pressure fell to 982 mb. This combined with high pressure building into Iowa from the northwest resulting in a very strong pressure gradient across the state. The strong upper level trough of low pressure became negatively tilted as it lifted northeast across the central US, aiding in the low pressure intensification. A strong push of moisture took place ahead of the storm. A mixture of rain and snow developed north and northwest of the low pressure track. As the dry slot lifted northeast toward Iowa, the airmass became increasingly unstable. A large area, for December, of thunderstorms developed over northeast Kansas into northwest Missouri, then pushed rapidly across Iowa during the evening of the 19th. A mixture of rain and snow occurred across southern Iowa during the early evening. The rain/snow line shifted southeast with much of the thunderstorm activity occurring as thundersnow. The thunderstorms brought with them a mixture of snow and some freezing rain. Though the freezing rain was not of a significant amount, it did help to cake the snow that was falling at a one to two inch per hour rate onto trees and power lines. The snow spread north quickly through the evening and early morning hours. The heaviest snow fell in a band about 50 miles wide that extended from near the Omaha-Council Bluffs area, through Des Moines and Waterloo, and eventually all the way to Marquette. Snowfall of 8-12 inches was common in this band with some amounts over 14 inches. Outside of the heavier band of snowfall, 2 to 5 inches of snow was reported. Roads became treacherous quickly with the heavy snow falling on road surface temperatures that were just above freezing. Numerous traffic accidents and injuries were reported, along with some fatalities. The largest accident occurred on Interstate 30 near the Williams exit. The location was near mile marker 150. Thirty cars were involved with two fatalities reported. There were two deaths that occurred in the pile up. A 27 year old female, pregnant with twins, was outside of her car looking for her young son when she was struck and killed. A 43 year old female was killed in her stopped vehicle when another car struck hers. There waere also seven others injured in the pileup. Blowing snow became a major issue as the night progressed. Blizzard and near whiteout conditions were widespread by sunrise across the state. Roads drifted shut in many areas with numerous road closings. Interstate 35 was closed from Ames to the Minnesota line much of the day on the 20th until mid-day on the 21st. Conditions became bad enough that most activities in the state were cancelled for both the 20th and 21st. The strong winds caused snow drifts 5 to 10 feet high in many areas. Blizzard conditions were reported over most of the Des Moines CWA. Sustained winds of 25 to 35 MPH were common across the CWA, with frequent gusts of 45 to 55 MPH. Some of the highest winds included 43 MPH gusting to 57 MPH at Ottumwa at the peak of the storm. Their peak gust was 60 MPH. Other locations at the peak of the storm include Mason City with 36 MPH gusting to 48 MPH, Knoxville 38 MPH gusting to 50 MPH, Marshalltown 36 MPH gusting to 49 MPH, Newton 36 MPH gusting to 53 MPH, Oskaloosa 43 MPH gusting to 54 MPH, Waterloo 39 MPH gusting to 52 MPH, Des Moines 32 MPH gusting to 54 MPH, Ames 35 MPH gusting to 50 MPH, Carroll 39 MPH gusting to 46 MPH, Chariton 28 MPH gusting to 49 MPH, Lamoni 35 MPH gusting to 50 MPH, and Grinnell 39 MPH gusting to 50 MPH.

Source: NOAA Storm Events Database, event_id 417152. Narrative written by the NWS forecast office that issued the report.