Winter Storm: Dec. 23-25 Update #4

Our first round of snow across the northern plains has came to an end, and we are now looking towards a digging trough in the western plains and its' associated low pressure system that should strengthen and create blizzard or near-blizzard conditions across a large part of the northern plains.  Both the northern and southern streams of the jets will have ample support for a low pressure system and result in rapid intensification of the 500mb low creating a large closed low across the northern high plains.  This will aid in pulling the intensifying surface low from the Mississippi valley region back westward towards the northern plains.  This will prolong the snowfall for much of the plains, and also results in an increased pressure gradient leading towards are high winds expected tonight through Friday.

For today we'll see some scattered snow showers and mixed precipitation across the state of Iowa and adjacent areas, with little accumulations for most areas.  This may give roadway crews time to clear the roads somewhat and make travel a little less hazardous.  However, conditions will deteriorate very quickly this evening as moderate to heavy snow begins to fall and winds continue to increase.  Models continue to forecast the heaviest snowfall across western Iowa, with the potential for 8-12" or more during the overnight hours tonight with snow continue through Christmas day.  Snowfall totals still look to range in the 16-18" with isolated higher amounts throughout western Iowa, Minnesota, the eastern Dakotas and nearby areas.

While afternoon and evening travel may not appear hazardous with the lack of precipitation falling, keep in mind that conditions will deteriorate rapidly this evening as our next storm system begins to impact the area.  Moderate to heavy snowfall will fall throughout the nighttime hours and continue through the day on Christmas.  Here is some of the latest snowfall totals for the past 24 hours at Iowa cooperative observer stations (this should fill in with all of the reports as they are received today):