PM Update: Milder this week, more wintry by weekend

The trend towards milder temperatures continues this week, as high temperatures rose into the upper 40’s and the 50’s throughout the area on Tuesday. The modifying airmass and stagnant high pressure are initially to blame this week, with no reinforced source of cold arctic air. But by Wednesday into Thursday, the warm air will be forced northward by a surging warm front and associated storm system moving through the Great Lakes.

The warm front moving northward on Thursday will bring an unseasonably warm airmass with it. Southerly winds will pump in very mild air, with temperatures rising into the 60’s by Thursday afternoon. But the warmth will be short lived, as a cold front moving through the area on Friday will mark the beginning of another infiltration of arctic air.

NAM model showing high temperatures in the lower to middle 60's in parts of the area on Thursday afternoon.

NAM model showing high temperatures in the lower to middle 60’s in parts of the area on Thursday afternoon.

Wintry potential by this weekend could cause forecast headache

After a cold front moves through the area on Friday, arctic air will have poured into the West-Central United States. As it slowly seeps eastward towards the Northeast United States, a large trough over the Central US will begin its battle with a developing southeast ridge. Individual disturbances and perturbations are inherently hard to predict at this range, but forecast models are keying in on a potential system sliding through the Ohio Valley and Northeast early next week.

Although the position of the trough over the Central United States suggests our area will immediately have to deal with mid level warming and lack the synoptic setup for a big winter storm, the arctic high pressure positioned just to our north seems sure to create some surprises — and headaches — for forecasters. Cold air near the surface could create a mixed precipitation event, especially across the northern suburbs and higher elevations.

At this range, this remains a low confidence forecast. But it appears the forecast models are strongly hinting at the potential for some issues early next week. Our technical discussion from yesterday dives more into this potential.

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