A developing storm system will deliver a fresh blanket of snow to parts of the Midwest, Great Lakes and Appalachians through midweek. Although portions of the Northeast may start out with snow or a wintry mix, most areas in the region will change over to rain during this storm.

The snow we expect the next couple of days is from the same weather system bringing a dangerous threat of severe storms and tornadoes to the South.

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The National Weather Service has issued winter storm watches from Lower Michigan to northern Indiana and east-central Illinois. In addition, winter weather advisories are posted from Upstate New York and northeast Pennsylvania to portions of New England.

The Setup Sunday/Monday

Below is a look at our snowfall forecast and the timing for this storm.

How Much Snow and Ice?

Uncertainty in the exact track of the surface low-pressure system still exists, governing the placement of rain/snow lines and the placement of where the heaviest snow will fall.

In addition, the magnitude and extent of the cold air (in other words, low-level cold air near the surface cold enough to support snowflakes surviving to the ground) also remains somewhat in question during the storm's initial stages.

However, once the low-pressure system has strengthened rapidly, deep-enough cold air will be drawn in the storm's cold conveyor belt to support significant snow to the west, northwest and eventually southwest of the low's track.

Right now it looks like there will be a narrow band of heavier snow in portions of the Midwest and Great Lakes. However, the exact placement of that heavier band will depend on where we see the greatest overlap between the available cold air and moisture on the northwest side of where the area of low pressure tracks.

Here is an overview of our snowfall forecast at this time:

Best chance for heavy snow (6 inches or more): Lower Michigan, northern Indiana, northeast/east-central Illinois (potentially including far southern Chicago suburbs), and the central Appalachians. There may also be lake-enhanced snow in some eastern Great Lakes snowbelts Thursday into early Friday.Mainly less than 6 inches:Ozarks, mid-Mississippi Valley, interior Northeast and New England (northwest of I-95).Ice accumulations:Some locations from the northeast Pennsylvania to Upstate New York and interior New England may see light freezing rain accumulations. Most areas should see less than a quarter inch of accumulation with the main impact from the ice being slick travel conditions Tuesday night into Wednesday.

Sunday's Outlook

(Areas in pink denote either rain or snow may fall. Areas in blue denote where snow may fall.)

Monday's Outlook

(Areas in pink denote either rain or snow may fall. Areas in blue denote where snow may fall.)

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Forecast Timing

Tuesday

Daytime: Snow in the Rockies and Front Range of Colorado may spread into the High Plains of western Kansas, northeastern New Mexico and portions of the panhandles of Oklahoma and Texas.Night: Snow or a wintry mix is expected from northeast Pennsylvania and Upstate New York to New England. Any freezing rain in the Northeast could cause slick travel conditions. Rain may change to snow in parts of northern Arkansas, southeast Missouri and central Illinois.

Tuesday Night's Forecast Rain/Snow/Ice

Wednesday

Daytime: Rain continues to change to snow across parts of the Ozarks and mid-Mississippi Valley, including parts of northern Arkansas and southeast Missouri, then into Great Lakes. Snow may be locally heavy from central and northeast Illinois (potentially near or south of southern Chicago suburbs) into Lower Michigan. Wintry mix continues in Upstate New York and interior New England where slippery travel is possible due to freezing rain.Night: Rain changes to snow across the Ohio and Tennessee Valleys into the Appalachians. Snow continues in portions of the Great Lakes, particularly Michigan and northern Indiana. Most of the wintry precipitation in New England changes to rain.Intensifying winds may lead to sharply reduced visibility later Wednesday/Wednesday night.(FORECASTS: | |)

Wednesday Night's Forecast Rain/Snow/Ice

Thursday

Wind-driven, heavy snow may persist in the eastern Great Lakes, Ohio Valley and Appalachians.Rain persists in much of the Northeast, possibly ending as a brief period of snow in the interior Northeast.(FORECASTS: | | | )

Thursday's Forecast Rain/Snow/Ice

Check back with us at weather.com for the latest on this potential storm and any likely forecast changes ahead.

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