At a Glance

Heavy snow will blanket an expansive area through Sunday night.Accumulating sleet or ice is likely in some areas.Gusty winds will pick up on Sunday. This may also lead to power outages in some areas.

Winter Storm Harper is spreading a mess of snow, ice and wind from the Midwest into the Northeast through Sunday night.

(COMPLETE FORECAST: Winter Storm Harper)

Here are five forecast details to help you better understand this latest winter storm.

1. Strong Winds Will Spread from the Plains to the Northeast

Strong, gusty winds will stretch across the East on Sunday.

These strong winds combined with heavy snow and ice may lead to white out conditions, power outages and tree damage.

2. The Heaviest Stripe of Snow

A swath from the Ohio Valley into parts of New England appears poised to pile up the most snow of any location east of the Rockies.

Parts of this swath will pick up over a foot of snow. Some locations in New York state and northern New England may exceed 24 inches of snow.

3. Interstate 95 Corridor a Complicated Forecast

As is often the case with snowstorms in the Northeast, Winter Storm Harper's most difficult forecast is along the heavily populated Interstate 95 corridor.

Due to the general track of the storm's center, precipitation is expected to change from snow to sleet to freezing rain to rain.

In general, we expect lighter accumulations and a quicker change to rain south of the New York City tri-state area, including Philadelphia, Baltimore and Washington D.C., in contrast with last weekend's .

Father north, especially from the New York City tri-state area to the Boston metro, you could see a large variation in snowfall from south to north. Higher snow totals could occur in cities along the Interstate 95 corridor if the colder air remains in place there.

In any case, black ice will be a big threat in many of the big cities as temperatures plummet on Sunday.

4. Ice Threat and Power Outage Potential

Winter Storm Harper will also bring a zone of freezing rain and sleet from the Ohio Valley to New England this weekend.

In some areas, this may lead to sufficient ice accumulations to make many roads, not just bridges and overpasses, slick, and may add a glaze of ice on top of previously fallen snow.

The combination of enough ice and snow on trees and power lines, plus the added stress of strong winds, will likely lead to some power outages in these areas.

5. The Cold Quickly Follows

The coldest air of the season so far will plunge into much of the Midwest, South and East hot on Harper's heels. This bitter cold makes it more important for those who lose power to have an alternate source of heat.

The quick drop in temperature could lead to a flash freeze and slippery travel in some areas especially along the I-95 corridor on Sunday.

(COMPLETE FORECAST: Arctic Blast)