The storm system could begin affecting parts of Iowa late tonight and into early morning. Snow could fall in Iowa through Tuesday morning. By that time accumulations could be heavy, ranging from 4”-8” with locally higher amounts approaching 10” in places.
So why the difference with this clipper system? For starters this one is packed with moisture. Tonight it is expected to stregthen which is a little bit unusual for a storm of this type. That’s something normally seen from a storm system that dips south across Oklahoma or Colorado and swings north through the Upper Midwest.
What’s also aiding the heavy snowfall projections is the ratio. Unlike the last couple of winter storms, this particular one is dealing with a much colder air mass. That is expected to contribute to a higher snowfall rate based on the available moisture, perhaps 15” for every 1” of liquid. Obviously we are not looking at 15” but you can see where .5” can become a bigger deal
As a result of all this, the National Weather Service has issued a Winter Storm Warning for counties shaded in pink above. Areas in purple are under a Winter Weather Advisories and areas still shaded in blue are still under a Winter Storm Watch.
There is one unusual thing I must point out about these warning and advisory headlines. Warnings are normally issued when any given area can expect snow fall of more than 6”. But there are portions of eastern Iowa where heavy snow is expected but an advisory has been issued instead. That’s because the National Weather Service in the Quad Cities is pointing out that warning criteria is met when the 6” or more of snow falls within a 24 hour period. This will be closer to a 36 hour event. As a result, they went with a prolonged advisory rather than the warning.
Either way, this storm will greatly affect travel in the coming days and we will provide updates as it moves in. Remember, you can submit your photos of the storm to [email protected]