Monday downpours give way to gusty, Lake Michigan churning “NNE” winds Tuesday blowing the length of Lake Michigan. Temps rebound to the 80s Wednesday and evidence of late season heat and humidity beginning this weekend grows

by: Tom Skilling, Bill Snyder, Jennifer Kohnke

Posted: Aug 14, 2023 / 11:18 PM CDT

Updated: Aug 16, 2023 / 10:10 AM CDT

WARM SEASON RAINS ARE NOTORIOUSLY UNEVENLY DISTRIBUTED

Monday’s rains followed that pattern. While downpours produced flooding and rain totals topping 3” in portions of the Chicago area, as little as 0.08” fell in Herscher and 0.09” at Lowell, IN.
There were new and training downpours flaring late Monday night up and down the western Lake Michigan shoreline including a swath of Lake and Cook County.
Monday afternoon satellite imagery was quite dramatic in its presentation of the late summer storm. The huge comma-shaped curl in the clouds are more commonly seen with well developing storms at cooler times of the year. The copious supply of moisture which was available to Monday’s system was behind the local downpours which drenched parts of the area.

“Full fetch” NNE winds—the term full fetch refers to winds which blow the length of Lake Michigan on their way into the Chicago area. These are uniquely able to transfer wind energy to the lake surface building waves in the process. Lake Michigan will take on a wind-whipped appearance Tuesday with white caps. Rip currents which result in such a set-up promise challenging swimming conditions on Chicago’s beaches Tuesday.

A RANGE OF COMPUTER MODELS, A NUMBER POSTED BELOW, ARE PREDICTING A HUGE DOME OF HOT AIR BUILDING OVER THE NATION’S MID SECTION

That multiple models from a full range of meteorological forecast agencies are simultaneously predicting the development of a mammoth hot air dome strengthens confidence that we’re on the way to heat. What will be monitored closely are any indications t-storms develop on the northern flank of the hot air mass, and any sign such development might take place close enough to Chicago to interfere with hot air gaining a foothold in this area. At present, evidence such t-storms will develop seems unlikely. But we’re still days away from the heat’s predicted onset so we’ll continue monitoring any updates in forecast reasoning.