Incoming mild air predicted to produce a tie for the second warmest Thanksgiving in Chicago; air mass behind new temp records across 8 Plains states Wednesday

 

60-degree and higher Thanksgiving temperatures are rare—and so are 64-degree high temperatures at such a late date.  Yet BOTH have an excellent chance of occurring before the sun sets Thursday evening. That’s when cold frontal rains are likely to sweep the area bringing a wintry temp downturn expected to make Black Friday shopping a “bundle-up” affair.

The Thanksgiving warm-up comes as a mass of unseasonably warm air, responsible for record-breaking warmth across sections of eight states up and down the Plains on Wednesday, trudges eastward and into the Chicago area.

 

The wintry cold front which hits tonight is to send Chicago high temps diving 25-degrees by Friday—a drop equivalent to the decline in normal highs from October to December

 

Powerful and abnormally mild south to southwest winds are predicted to gust as high as 40 mph Thursday afternoon producing temperatures nearly 20 degrees above normal. But, that’s to change once an evening cold front blasts across the metro area, shifting winds northwesterly—a flow with origins over the building Canadian snowpack. The temperature plunge which ensues is to take Friday high temperatures down 25-degrees—the equivalent of the drop in “normal” high temperatures over the nearly two months from October 13 to December 6 —only this change is to happen in just 24 hours!

It’s quite unusual for a 64-degree temp this late in the season

 

We’ve pointed out all week that Thursday daytime highs in the 60s would make this the first Thanksgiving in 14 years to record 60s! An actual high of 64-degrees Thursday would equal Chicago’s second warmest Thanksgiving last set in 1914. A reading that warm has occurred this late in only 19% of the 142 years for which we have temperature records in Chicago.

 

By contrast, the holiday produced a 47-degree high a year ago. That means many Chicagoans will sit down to a holiday dinner on a day 17-degrees warmer than 2011!

First daytime 30s of the season coming Friday and Saturday; Saturday’s predicted 35 could become autumn 2012’s chilliest to date

Daytime temperatures have yet to remain in the 30s this season—a situation likely to change Friday and Saturday as readings struggle to the mid or upper 30s.

 

Potentially wintry weather system being monitored for later Monday into Tuesday

Many details remain to be ironed out on a potentially wintry weather system which could impact the Midwest later Monday, Monday night and Tuesday. The system is still 4 to 5 days away, plenty of time to update the forecast of its track across the Midwest. But, it marks the first time a disturbance, still out over the Pacific late Wednesday, has shown signs of straddling a sharp temperature demarcation zone  as it treks across the country toward the Midwest.  Recent commuter forecasts have suggested a track close enough to Chicago to warrant careful monitoring of the fledgling disturbance in coming days.