IT’S BEEN A GORGEOUS WEDNESDAY with 100% of the day’s possible sunshine and winds a fraction of the 25 to 40 mph gusts (highest at the lakeshore and out over Lake Michigan) which blew across Chicago Tuesday stirring waves and rip currents along Lake Michigan and on Chicago’s beaches.  

Wednesday Chicago weather couldn’t have been more different with flocks of weekday beachgoers enjoying a quiet  lake free of the 4 to 6 ft. waves which crashed on Chicago shores Tuesday.

The day’s SOUTHWEST winds overcame lake cooling—so it was warm right up to the lakeshore! Peak wind wind gusts Wednesday reached 17 mph at O’Hare and 18 mph at Midway Airport.

Interestingly, veteran NWS Chicago weather observer Frank Wachowski informs us the last time a day produced 100% of its possible sun was back on July 10.

9 of the past 12 days have produced temps AT or BELOW NORMAL—but only marginally so.  August is currently a veritable statistical “wash”–in other words, virtually normal with month to date temps, when today’s temps factored,  averaging 0.4-deg BELOW NORMAL—-just a fraction of a degree from the most recent  smoothed 30 year average! And the month’s opening 16 days will go into the books running just 0.5-deg cooler than the same period a year ago.

HERE’S WHAT’S AHEAD WEATHERWISE FOR CHICAGO:

Southeastbound cool front reaches the area with showers and some thunderstorms Thursday morning. The bulk of these could be passing across the city a portion of the morning rush hour—with rain likely to impact 50 to 60% of the area. Spotty lead showers could be in parts of the area as early as 4 to 6 am.  But the bulk of the showers will sweep through between 6 and 10am.

Clearing, breezy and less humid weather follows with some wind gusts to 30 mph delivering the drier air which will have mostly sunny skies taking over in the afternoon and a cloudy, rain start to the day.

Friday and Saturday look BEAUTIFUL—with comfortable humidities and slow daytime warming taking place as a dome of HOT AIR begins building into the Midwest.  By later Saturday, an increase in humidities will begin to be felt—and the hotter temps which take hold Sunday, Monday and Tuesday should be accompanied by MARKEDLY MORE HUMID AIR. Dew point, a measure of atmospheric moisture, with rise from the mid 50s Saturday morning to the mid 60s by Saturday evening then surge into the low to mid 70s Sunday afternoon through Tuesday.

The DOME OF HOT AIR predicted to develop continues to be featured by virtually all computer forecast models available to us.  The one twist which is interesting and still not completely resolved is the insistence by several models that a Canadian high pressure will force a cold front to sweep across the area Sunday night and Monday. If that were to occur, it could interrupt or even derail heating.  But these same models building the most expanded HOT AIR DOME of the summer over the region.  My experience has been that an atmosphere forecast to warm dramatically aloft is likely to do the same thing down here at ground level. WHAT MAY HAPPEN Monday is that winds may shift off Lake Michigan—probably not as vigorously as some models are predicting. This could temper the heat on area beaches while inland areas would broil in the 90s—and with muggy low and mid 70-deg dew point to boot. The combination of heat and that level of moisture would send PEAK AFTERNOON HEAT INDICES  into the 98 to 106-deg range Sunday –and each afternoon from Monday through Tuesday

This a situation which will have to monitored. If the front forecast by some models verifies, that could impact the heating early next week.  But for now, it appears A PERIOD OF LATE SUMMER HEAT is on the way.  We’ll keep you posted.

A cool front will settle through the area Tuesday night and Wednesday, stalling south of Chicago with the potential for t-storm generating wave to move along it. With a jet stream overhead, any storm clusters may warrant observation as potential active t-storm producers.

HERE’S MY LATEST WEDNESDAY CHICAGO METRO FORECAST (8/16/2023)

TONIGHT: Increasing cloudiness and warmer. Several scattered showers or t-storms possible over portions of the area in the hours toward daybreak.  Low 65.

THURSDAY: A period of showers and t-storms likely—primarily in the 6 to 10 am period Thursday morning. Clearing, fairly windy, a bit cooler and turning less humid with skies becoming mostly sunny Thursday afternoon. A few northwest wind gusts to 30 mph. High 77. 

THURSDAY NIGHT: Mainly clear and cooler—but quite comfortable. Diminishing winds. Low 61—but mid 50s inland.

FRIDAY: Sunny with warm afternoon temps and low humidities. High 82—but  mid 70s beaches.

SATURDAY: Mostly sunny, warmer. Humidities begin to increase in the afternoon and evening. Southwest winds likely overcoming lakeside cooling. High 88

SUNDAY: Mostly sunny, breezy, turning hot and noticeably more humid. High 95—Peak heat indices:  98 to 102.

MONDAY: Partly sunny, hot—especially inland—and humid. High 93—but 80s beaches. Peak inland head indices: 98 to 102.

TUESDAY: Partly sunny, turning breezy, continue hot and quite humid. High 94. Peak heat indices:  100 to 106.

WEDNESDAY: More clouds, not as warm. Some clusters of showers and t-storms possible. High Wednesday 82—but 70s lakeshore.