Warmth, elevated humidity’s, an incoming cold front and a jet stream overhead are not a great mix if one want to avoid t-storms.
Modeling and radar scans depict t-storm bubbling up through the atmosphere and like to be traversing the Chicago area in the 5 to 9 p.m. time frame.
Thursday’s already featured t-storms—and temps have surged to within striking distance of 8 degree, marking the 8th time in this 20-day old month we’ve managed temps at or above 70. The month of April is running 7 degree above normal and 10 degree warmer than the opening 20-days of the month a year ago. April 2023 to date ranks 5th warmest of the past 151 Aprils.
Hail and rotating super cellular t-storms are occurring with warnings for severe storms and potential tornadoes already out in western Illinois. Radar there is indicating storm cells racing east/northeast at nearly 50 mph—near highway speeds. And you know the adage—fast moving storms are potentially damaging wind generating storms.
Those are the storms racing toward Chicago area airspace and modeled to be in our area in the 5 to 9 p.m. time frame. It’s that period there is the greatest concern some of these storm may prove severe and capable of damaging winds and spinning up tornadoes.
Storms may still be traversing northwest Indiana in the 8 to 11 p.m. time frame and don’t be surprised to see a weather watch issued for that area past the 8 p.m. expiration time of the Tornado Watch currently out for Chicago.
Windy, cooler weather locks in Friday with a pause in precipitation and temps, though still above normal—down as much as 15 degree from today’s warmth.
But chillier weather tightens its grip on the city this weekend with cold air aloft raising the potential for a good deal of cloudiness and even scat instability showers developing in the “warmer” hours of the day. With 20 degree temp predicted within a mile of the ground, don’t be surprised is some small hailstones occur with those spotty showers in a few locations.
Temps are to average below normal next week and into the week that follows with next week features frequently easterly winds off chilly Lake Michigan with its 45 degree current water temps, a development which promises little prospect for a return of 70s.
Longer range computer guidance is hinting at milder temps in the week which follows—a trend which we’ll be following with interest. But not before we open the week after next with at least modestly below normal temps.
HERE’S MY LATEST THURSDAY CHICAGO METRO FORECAST (4/20/2023)
Tornado Watch for all, but Northwest Indiana (though a second watch may be necessary there before the evening is out) until 8 p.m. Thursday night.
TONIGHT: Clusters of fast-moving, strong t-storms developing—some capable of hail, damaging straight line winds and a few possible tornadoes. Storms should be exiting Chicago 8 to 9 pm—and out of northwest Indiana by 10 to 11pm. Then cloudy spells, windy and cooler. Low 42.
FRIDAY: Clouds with mixed sun at times, windy and cooler—though temps will continue modestly ABOVE NORMAL another day. Gusts topping 40 mph likely. High 64.
FRIDAY NIGHT: Partly cloudy, breezy and cooler. Low 36.
SATURDAY: A noticeably cooler day with gusty northwest winds. Mixed sun and clouds. Daytime heating may produce a few isolated showers—some with with some small ice pellets possible. HIGH 48.
SUNDAY: Partly cloudy to cloudy, a bit breezy and cool for the season. Slight chance of a light shower or two by afternoon. High 53.
MONDAY THROUGH THURSDAY: Partly cloudy and cool. High Monday 56 with 55-deg highs Tuesday and Wednesday—but with upper 40s along Lake Michigan. Lows at night low to mid 40s—but some upper 30s inland.