22 | December | 2014 | The Weather Whisper

Three Day Water Vapor Loop – December 23-25, 2009

A major winter storm system stalled over the central United States during the week of Christmas 2009 and brought multiple rounds of wintery precipitation over Iowa from December 23-26, 2009. The first round of precipitation fell in the form of freezing drizzle or freezing rain during the early morning hours on the 23rd over central Iowa. A sharp gradient set up across Iowa as snow developed over northwest Iowa, rain in southeast Iowa, while freezing rain and sleet fell in between through the afternoon and evening hours on December 23. The precipitation finally transitioned to all snow from west to east on the 24th and 25th before tapering off on the 26th. The storm was so wrapped up around itself that the temperatures on Christmas Day across Iowa were flipped as north-central to northeast Iowa were in the 30s and the west-central to southwest portions of the state were only in the lower teens.

This storm produced heavy snowfall across western to northwestern Iowa, with a total of 24.0 inches at Spencer shattering the previous storm total record at that location by a full 5 inches. In fact, combined with several other winter storms in December 2009, Spencer set an all-time record monthly snowfall total for Iowa with 40.0 inches for December. Other snowfall amounts from the Christmas Week storm included 16.0 inches at Little Sioux, 15.7 inches at Hawarden, and 15.5 inches at the Sioux City airport. Further south and east of the heavy snow band, a substantial amount of ice accrual crippled several counties in west-central Iowa and the hardest hit counties were Audubon, Crawford, Carroll, Guthrie, and Greene. In these locations, around a half an inch to nearly an inch were reported and resulted in multiple down power lines, broken tree branches, and made driving extremely hazardous. Other portions of central Iowa received lighter ice amounts, generally around a tenth of an inch or less, but there was enough to cause significant travel problems on December 23 to 24, 2009. In addition to the heavy snow and freezing rain, very strong north winds of 25 to 35 mph developed on the 24th and continued into Christmas Day and either caused significant blowing and drifting of snow or blew down ice covered trees and power lines. Thousands of residents lost power due to this storm for several days, especially over west-central Iowa. The Governor of Iowa declared a state disaster for several counties in western Iowa. December 2009 finished as the second snowiest month on record in Iowa in terms of statewide average snowfall, only behind December of 2000.