Plains snowstorm

A storm system is causing heavy snow across the Plains states but warm air is expected to turn precipitation wetter by Friday. (AccuWeather.com / February 21, 2013)

The National Weather Service is forecasting that a system dumping as much as 2 feet of snow and significant ice accumulation across the Plains states will bring an inch or less of snow to Maryland on Friday, along with a mix of sleet, freezing rain and rain.

Thursday morning, 4 inches of snow fell within 90 minutes in North Kansas City, 2 inches within half an hour in Kansas City, and snowfall totals of 5-6 inches and rising were recorded, according to reports made to the weather service in Kansas City. Heavy snow continued into the afternoon, with 9-10 inches around the Kansas City area.

But by the time the storm moves to the north-northeast, warm air is expected to surge up from the south, creating an icy, wintry mix into the Ohio Valley and mid-Atlantic, according to AccuWeather.com.

To the Northeast, the storm is expected to mean another 6- to 12-inch snow event from Providence to Boston.

The weather service Baltimore/Washington office's forecasters explain that a warm front will be approaching from the southwest Friday. So while cold air in place over the region could support snowfall at first, precipitation is then expected to change over to a mix.

But even if freezing rain falls, it won't stay on surfaces for long, according to forecast discussions. Without a source of cold air to keep lower levels of the atmosphere below freezing, rain that freezes on contact will pull heat from the ground, actually warming the surface, forecasters wrote.

The local forecasters expect less than an inch of accumulation of any frozen precipitation.

High pressure and breezy conditions are expected to return late Saturday into early next week, when a system similar to Friday's could arrive on Tuesday, forecasters wrote.

Beyond that, AccuWeather's Henry Margusity is sticking with a long-term forecast that includes decent conditions for a coastal storm to develop -- the kind known to bring significant snowfall here. Margusity suspects some time around March 6, conditions could be prime for such a storm.

Have a weather question? E-mail me at sdance@baltsun.com or tweet to @MdWeather.