Midwest United States to be impacted first by major winter storm, followed by even colder temps

Precipitation type from Friday morning into Saturday

The major low-pressure system that is set to impact the northeast United States and eastern Canada over the weekend will first impact the Midwest of the United States. Above is the possible timing of the precipitation as the low develops on the lee of the Rocky Mountains.

Moderate to heavy snowfall is forecast across all of Iowa on Friday through Friday night. The heaviest amounts will likely fall across parts of northern Iowa, and the afternoon/evening commute will be impacts for most areas. North to northeast winds of 15 to 20 mph with gusts to around 30 mph will cause blowing and drifting snow and greatly reduce visibility at times. This will make travel hazardous across most or all of the state, especially Friday afternoon and evening. Please check weather.gov for the latest forecast updates if planning to travel. -NWS Des Moines, IA

The picture below show the active winter storm warnings (in pink) and winter storm watches (purple) issued by the National Weather Service:

Current watches/warnings issued by the NWS as of 8pm EST

...WINTER STORM WARNING IN EFFECT FROM NOON FRIDAY TO 6 AM CST
SATURDAY...

* WHAT...Heavy snow expected. Total snow accumulations of 5 to 8
  inches expected.

* WHERE...Central to southern Iowa.

* WHEN...From noon Friday to 6 AM CST Saturday.

* ADDITIONAL DETAILS...Travel could be very difficult. Patchy
  blowing snow could significantly reduce visibility. The
  hazardous conditions could seriously impact the
  afternoon/evening commute.

Moderate to heavy snow will spread from northwest to southeast across Iowa on Friday, reaching much of the state before or during the Friday afternoon commute. Gusty winds and snow falling heavily at times will combine to reduce visibility and lead to snow-covered roads and treacherous driving conditions. If traveling on Friday, please check the latest forecast updates and road conditions before setting out! -NWS Des Moines, IA

Part of the northern Plains will also see the snow, but the big story will remain the cold Arctic air that has been sitting on the N Plains and Prairie Provinces, prompting wind chill advisories in the US and extreme cold warnings for Canada. Even colder air will make its way as this system drags cold air from the Arctic on its backside.

Friday will be a snowy day across the area, with travel impacts expected. Snow will spread eastward as the morning commute progresses, with locations west of I-29 more likely to have early morning accumulations and slick roads. The greater impact will be during the evening commute, due to snow-covered roads area-wide, and reduced visibility with persistent light to moderate snow. Snowfall amounts of 4 to 8 inches are likely by the time the event ends Friday evening, with locally higher amounts possible. - NWS Sioux Falls, SD

Forecasted Low track from the National Weather Service