The showers which swept through the area earlier Friday (during the morning hours) “worked over” the atmosphere generating a more stable environment which has thwarted t-storm development. The storm-suppressing atmospheric CAP left in the wake of the morning rains, has defeated major thunderstorm development despite the day’s 86-deg high and mid 60-deg dew points indicating “moderate” humidity levels.
An isolated t-storm may still “pop” as the cap weakens this evening and early tonight—but it’s in the predawn hours—the hours beyond midnight, particularly the period from 2am to 8am time frame—that modeling suggests some gusty 40% coverage t-storms may develop.
These storms will form beyond the period of peak heating, which is the time of each day most likely to render the atmosphere MOST buoyant and therefore MOST prone to develop t-storms. But ,moderately high humidities and somewhat elevated atmospheric energy (CAPE) levels plus the fact ANY storms that DO develop will “bubble up” into a band of comparatively strong winds aloft and therefore be able potentially to bring some of that wind energy down to the surface in their wind gusts, yields a LEVEL ONE risk of severe weather on the Storm Prediction Center’s severe weather risk index. It’s NOT A HIGH RISK—but it’s not zero.
Once past the opening hours of the weekend Saturday morning, rain chances fade much of the remainder of the weekend—though there’s a slight chance an isolated shower could pop in a few areas as Sunday warms, This is to be a weekend with highs in the mid 80s and easterly afternoon lake breezes likely to hold shoreline and area beach high temps closer to the upper 70s to low 80s—is to remain rain-free.
Limited nighttime cloud cover plus the fact the moon will be contributed only 10% of its possible light to the nighttime environment, means this should be a good weekend to view the annual Perseids meteor shower, which astronomers tells us is to peak around 3am CDT Sunday morning. Meteors should emanate from the northeast sky—where the Constellation Pegasus resides—but keeping an eye on the full sky is not a bad idea, we’re told.
Another wave sweeps in early next week with our next rain & t-storm prospects. That happens late Sunday night into Monday night—a period likely to see some t-storm clusters. And another t-storm risk may arise Thursday and Thu night.
Beyond that, there are signs some heat may head this way. A series of 90-deg highs are modeled in the area next weekend into the following week. In fact, while this week is to finish temps within a few tenths of a degree from normal, temps next week may come in more than 2-deg above normal and the surplus the following week could grow to 7-deg above normal if current forecast trends hold. Goes to show is may be late in the summer season but hot weather is hardly behind us yet despite the fairly moderate nature of Summer 2023 to date here iun Chicago.
HERE’S MY LATEST FRIDAY CHICAGO METRO FORECAST (8/11/2023):
TONIGHT: Partly cloudy and warm with moderate humidity. An isolated shower or t-storm possible early. Better chance for gusty 40% coverage t-storms later tonight—mainly in the 2am to 7am time frame. Low 69.
SATURDAY: Chance of a few t-storms early, especially south half of the area. Otherwise becoming mostly sunny and warm with moderate humidities and easterly lake breezes developing along Lake Michigan. High 87—but upper 70s or low 70s beaches.
SATURDAY NIGHT: Only scattered clouds, seasonably warm. Low 67.
SUNDAY: Partly cloudy and warm with moderate humidities and easterly lake breezes again. Slight chance of an isolated shower brewing in the warmer hours of the day—but with very limited coverage. High 86—upper 70s beaches.
MONDAY: Clusters of showers and t-storms with a good deal of cloudiness, humid. High 81,
TUESDAY and WEDNESDAY: Generous sunshine and warmer. Cottony summertime cumulus clouds. High Tuesday 85; Wednesday’s high 90—but low 80s lakeshore on Tuesday.
THURSDAY: Clouds build—so do scattered thunderstorm prospects. High 84.
FRIDAY: Partly sunny and quite warm but lower humidities. High 88.