A deep upper-level low pressure system currently sits over the Great Lakes as a strong cold front continues to push south and east of the Gulf and Atlantic coasts, leading to a combination of chilly, well below normal temperatures for much of the eastern 2/3rds of the country, as well as wintry precipitation for the Great Lakes.
Article continues below
A cold continental airmass has begun to settle in as high pressure builds southward over the central and southern U.S.
Widespread, well-below normal high and low temperatures are forecast through the short-term period (Wednesday evening), with some upwards of 25 degrees below normal and many record tying/breaking temperatures possible.
Freeze Warnings are in effect across broad portions of the Central Plains, Middle Mississippi Valley, Ohio Valley, Tennessee Valley, Mid-South, and Central/Southern Appalachians.
Freeze Watches are in effect further south from northern portions of the Southern Plains east through the Lower Mississippi Valley and into the Piedmont.
Lows in the mid-20s to low 30s are currently forecast for locations in the Freeze Warnings Tuesday morning with lows in the low to mid-30s for areas in the Freeze Watches on Wednesday morning.
Areas to the north of the Freeze Watches and Warnings, despite already having seen their first freeze, will still experience well below normal, frigid temperatures Tuesday, with highs in the upper-30s to low 40s for the Northern Plains and Upper Great Lakes and low to mid-40s for the Middle Missouri Valley east to the Lower Great Lakes.
Highs on Wednesday should warm by about 5-10 degrees across the region.
Further south, while a widespread freeze is not currently expected, morning lows on Wednesday will bottom out in the upper-30s to low 40s across much of the Gulf Coast.
In addition to the chilly temperatures, additional waves of low pressure rotating around the broader upper-level low will continue strong/gusty northwesterly winds across portions of the Great Lakes with a wintry mix of rain and snow showers expected through Wednesday.
Any snow accumulations should generally remain on the lighter side with the exception of the Upper Great Lakes, particularly the Upper Peninsula of Michigan.
Snow showers today will taper off through the day tomorrow, with total accumulations upwards of 6-12 inches possible for some higher elevation, inland locations.
Heavy rain is forecast to the east of the cold front as it pushes through Maine during the day Tuesday.
Anomalously high moisture from the Gulf Stream will be advected northward ahead of the front and help to enhance rain rates/rainfall totals for showers and thunderstorms along the front.
There is a Slight Risk of Excessive Rainfall in effect for eastern Maine where 2-4 inches of rainfall is forecast, with locally higher totals between 5-8 inches in higher terrain areas possible, leading to the risk for scattered instances of flash flooding.
Elsewhere, warm temperatures 10-20 degrees above average will continue for much of the West the next couple of days as an upper-level ridge remains in place.
Highs Tuesday and Wednesday will be in the mid- to upper 70s for most of the Northern Rockies, Pacific Northwest, and Great Basin, with 80s for the I-5 urban corridor in Oregon.
A warm front will move east over the High Plains on Wednesday, bringing some relief from the chilly temperatures to the Northern High Plains with highs in the mid-60s to low-70s. ■