Winter Storm in Iowa, December 10 to 11, 2000

The first major winter storm system in nearly two years struck Iowa during the night of the 10th through the day on the 11th. A large Arctic high pressure area was poised to the northwest of Iowa. Cold air spilled south into Iowa with temperatures falling into the single digits above and below zero over nearly all of the state prior to the storms beginning. During the afternoon of the 10th, low pressure began developing over the southern Rockies. The surface low took a track northeast passing near Saint Louis, MO to just north of Indianapolis, IN by late on the afternoon of the 11th. This track was similar to the track taken by the last significant snowstorm to affect much of Iowa on 31 December 1998 through 01 January 1999. Two factors took place to produce the snow in Iowa. Initially, snow broke out over the state as warm air was lifted over the cold dome during the evening of the 10th into the early morning of the 11th. This isentropic lift zone was replaced by the dynamics of the storm itself toward dawn on the 11th when heavier snow developed. Some of the snowfall was convective over the far southern part of the state. Nearly every reporting station in the Des Moines CWA reported at least 6 inches of snow from this system. Six to eight inches of snow were common over the north half of the state, while over the south half snowfall amounts were generally in the nine to twelve inch range. The heaviest snow band was generally across the second tier of counties north of the Missouri border. Some convection took place across that area which enhanced the snowfall. The heaviest snowfall total came from the Ottumwa area, where fourteen inches of snow was recorded. Several locations were close to a foot from Ottumwa west toward Osceola. Coming in close behind was Indianola, in Warren County, with eleven inches. The snow hampered travel in many areas, but now as badly as is often the case. The light fluffy nature of the snow made it fairly easy to blow off the highways. Many of the roads were reported only partially snow covered even during the height of the storm. The light nature of the storm did present some other problems however. Gusty northerly winds of 20 to 35 MPH produced significant drifting and some blowing of the snow. The biggest problem was along east to west highways. Travel was not recommended over the south third of Iowa by the late afternoon hours. Schools closed across most of the state by the afternoon of the 11th and many remained closed on the 12th as well. Numerous businesses closed and some Government offices closed early on the 11th. Another problem with this storm was with the cold temperatures and the winds. Temperatures close to zero F. combined with the 20 to 35 MPH winds produced wind chill values across the entire state in the 35 to 50 degree below zero range. Although not unusual for Iowa, these readings were colder than had been experienced during the past few winters. Actual property damage was quite minor during this event. There were report of spotty power outages caused by the cold and some icing on power lines. The winds were of such speed that some "galloping" of power lines was observed. With the very cold temperatures, the wires were brittle and susceptible to breakage. No long lasting or extended power outages were reported.