Temps cooled over yesterday’s balmy 69 at O’Hare and 71 at Midway—which had been early October level temps.

By comparison, highs Tuesday only made it to 54 at O’Hare and 56 at Midway readings some 15-deg cooler than on Monday.  And as northeast winds locked in Tuesday afternoon, temps had fallen back to the  mid to upper 40s up and down the western Lake Michigan shoreline. Late afternoon readings had pulled back to 46 at Waukegan, 47 at Wilmette, 48 Michigan City, Indiana and 49 at Calumet Harbor and at Burns Harbor in Indiana. 

The northeast winds are the result of a circulation developing beneath the southern flank of a Canadian high pressure ridging southward into the Midwest and the far eastern side of a developing low pressure in eastern Colorado and western Kansas.

It’s the Colorado/Kansas system which is eastbound and likely to bring Chicago occasional rain beginning late tonight in the pre-dawn hours of Wednesday morning—though some precursor sprinkles may arrive earlier.

The track of that western system is likely to tug warm air northward toward Chicago and into the southern sections of the metro area Wednesday.  This introduces the likelihood of 60+ deg temps surging northward to near the city—and with such warm nearby, even introduce an isolated t-storm or two Wednesday.

Most rainfalls will range from a few hundredths of an inch out of the incoming disturbance and –but a few spotty locations may see totals in the quarter half in range by the time the autumn system clears the area.

Cool air riding northwest winds on the storm system’s back side will pull moderately cooler air into the area Thursday, Friday and Saturday (Veterans Day).  Daytime highs may be hard pressed to get out of the lower 50s on those days.

Looking ahead, modeling Chicago area temps rebounding with highs in the 60s much of next week and a weekly average temps likely to come in more than 11-deg above normal next week.

The dominance of mild Pacific air and melted snow in a wide swath of the Lower 48 which at one point a week ago had nearly 18% of the country under a layer of snow.  NO LONGER!  The National Weather Service analyzes on 4.4% of the Lower 48 sitting beneath a layer of snow Tuesday.  That means just a quarter of the area which was snow covered a week ago bears a cover of snow Tuesday.

Interestingly, WINTER WEATHER ADVISORIES are in effect tonight for the northern Wisconsin/Upper Michigan border area where modest accumulations of as much as 1-2″ may occur.  Northeast Minnesota’s ARROWHEAD area on the lake Superior shoreline may see half foot snow accumulation overnight.

One other note, November’s opening 7 days will have averaged nearly 3-deg above normal by the time today ends at midnight tonight.  But that 7-day period has come in nearly 8-deg COOLER than the same period a year ago.


TONIGHT: Cloudy with strengthening winds. A few sprinkles possible this evening into tonight—but more widespread occasional light rain develops late tonight, beginning in the pre-dawn hours of Wednesday morning.  Low 46.

WEDNESDAY: Cloudy, breezy and becoming milder—especially southern sections. Some periods of rain—even a modest chance for an solated t-storm. High 57—but only low 50s on the North Shore ranging to the mid to upper 60s south of the city, especially toward Kankakee, Morris and Rensselaer, IN.  

WEDNESDAY NIGHT: Rain ends late then partial clearing, fairly windy and cooler. Low 44.

THURSDAY: Partly sunny, windy and cooler. High 53.

FRIDAY: Mostly sunny, cool and a bit breezy. High 50.

SATURDAY: Mixed sun yields to incoming clouds, cool. Much calmer. High 51.

SUNDAY:  Opens cloudy—chance of some showers. But clearing follows. Cool. High 55.

MONDAY: Sunny and milder. High 62.