Two weeks after a powerful blizzard brought much of the state to a standstill, many travelers face some tough decisions this Christmas. Winter storm watches are already posted for a period beginning Wednesday and running through Friday if not longer.
What will give people headaches this week is they want answers and, to be honest, there’s just no easy answers. Unlike the blizzard, this storm could cause problems in a number of different ways. Here in eastern Iowa, rain, snow, sleet and the dreaded freezing rain are all possible. The doubt lies in how much of each any particular area will see.
So here we go. And remember, the slightest of temperature changes can dramatically change this forecast…
Although there are some precip concerns for tonight, I want to first focus on the Wednesday to Thursday time frame. That National Weather Service in the Quad Cities forecasted a “wintry mix” for much of eastern Iowa during this time. However, what type of mix could have significant impacts on travel.
The strong low pressure system is expected to surge north into Iowa, first passing west of Des Moines. When/if this happens, a large amount of warm air will come with it, pushing temperatures above the surface well above freezing.
Problem is, the surface might still be below freezing. Depending on the vertical profiles at any given location, this could lead to a significant freezing rain event. Worst case scenario, some places could see a major ice storm with ice accumulations of a half inch or more.
It’s also possible some of the precip could fall as sleet. Although this still creates travel problems it would greatly reduce both ice and snow accumulations with this storm.
At this time the greatest threat for ice accumulations appears to be along and near the Highway 30 corridor, especially Cedar Rapids. But any shift could move that ice threat closer to Interstate 80 or Highway 20.
Further north, although a wintry mix is forecast, a greater threat exists for significant snowfall. Regardless of what falls, moderately strong winds could create blowing snow. Further south, if ice collects on the ground, tree and power line damage is a strong possibility.
There’s also another threat. If the surface warms and the precip falls as plain ol’ rain, a flooding event could occur. Because of the strong snow pack, the water will have very few places to go. After all this, cold air will rush in and snow will take over by Friday. The bad news is the low is expected to linger over Iowa, so light to moderate snowfall could continue through Saturday.
All in all a very dangerous situation could develop over much of the state. I can’t stress enough how important it is to keep up to date with the latest information. This storm is many time harder to forecast than the blizzard of two weeks ago and the final track and outcome could change. The slightest shift could mean major changes, especially when we’re talking about a possible ice storm.
We’ll continue to monitor the situation and provide updates when possible.