Showers and thunderstorms on tap for Thursday

FIRST THE WEATHER HEADLINES—

–What a difference a year makes. We began a 5-consecutive day hot spell on this date last year with daytime each of the 5 days from August 24-28 at or above 90—and a 6th day (Aug 29) with a high of 89. August a year ago ended up producing eight days at or above 90. This August, which ends a week from today–next Wednesday at midnight —appears on track to produce just 2 with a potential third 90 if Sunday manages a 90-deg high, which isn’t completely out of the realm of possibility.  To date, August 1-24, 2022, is averaging 1.9-deg cooler than a year ago.

–A few showers and some thunderstorms have popped in Iowa, Minnesota and western Wisconsin and there’s a chance several scattered showers, a few possibly thundery, could hold together and reach Chicago in the hours around and just after daybreak Thursday. Coverage of any rain at that time would likely come in around 30% of the area.

–Daytime heating and a boost in humidity Thursday is likely to produce scattered thunderstorms which would bubble up over perhaps 40 to 50% of the area in the afternoon and evening hours. The period from 2 to 8pm CDT Thursday would appear the period at greatest risk for these storms.

–A cold front is to sweep over Chicago near 9pm Thursday evening (give or take an hour)–shifting winds initially to the northwest.

–Friday becomes dicey for swimmers and mariners along and off the Chicago shoreline as FULL FETCH (i.e. full length of Lake Michigan) “NNE” lock in and strengthens. This is likely to build seas into the 3 to 6 ft. range while initiating rip currents. It’s the type of wind and wave regime likely to necessitate a BEACH HAZARDS STATEMENT on Friday and into Friday night.

–“NNE” winds travel a 280-mile swath of Lake Michigan given the wind plenty of time to cool over the lake waters. So, Friday is likely to end up the coolest of the next 7 days with declining daytime humidities Friday. Dew points, which may start off in the low 60s with early clouds, are to drop Friday afternoon and evening into the low 50s. Clearing will accompany the declining atmospheric moisture levels Friday.

–Not to worry, warm, humid weather fans. While lake breezes will limit shoreline highs a bit while low 80s occur inland Saturday, Sunday’s well organized “SSW” winds will overcome any lake cooling pushing near 90-deg warmth up to and over area beaches and offshore waters. And the warmth and humidity hold Monday.

–Scattered 30% coverage thunderstorms are to develop Sunday afternoon–but maximum t-storm coverage amounting to as much as 50% of the metro area–is to occur later Sunday night into Monday.

–Early estimates on potential rainfall, which is need in the city given how dry August has been running with only a third its normal rain, run in the 0.4 to 1.2″ range if all the potential bursts of showers and t-storms materialize between now and next Tuesday.

–A cooler northwest upper flow pattern ushers in cooler and drier air into the area Tuesday forward next work week.

HERE’S THE LATEST CHICAGO METRO FORECAST

TONIGHT: Partly sunny this evening–but clouds increase overnight, a little warmer. Chance of several scattered showers, a few potentially thundery toward morning over up to 30% of the area. Low 66.

THURSDAY: A good deal of cloudiness, warm and becoming more humid. A few showers, some possible thundery early.  Scattered 40 to 50% coverage thunderstorms develop–the greatest number in the 2 to 8pm period Thursday afternoon and evening. High 82.

THURSDAY NIGHT: Early showers or thunderstorms–then cloudy spells. Low 66.

FRIDAY: Early clouds give way to more sunshine, becoming breezy, cooler and noticeably less humid as the day proceeds. High 76–but mid to upper 60s along Lake Michigan.

SATURDAY: Mixed sun and clouds, not as windy and a little warmer—especially inland. High 83–but mid 70s beaches.

SUNDAY: Clouds and some mixed sun, breezy, warmer and more humid. Scattered mainly afternoon thunderstorms impacting up to 30% of the area. More numerous storms at night. Hight 88.

MONDAY: Mixed clouds and sun, warm and humid. Several thunderstorms possible. High 87.

TUESDAY: Cloudy spells, still humid–but not as warm along Lake Michigan. Chance of a shower or t-storm. High 84–but cooler lakeshore.

WEDNESDAY: A good deal of sunshine, breezy, cooler and less humid. High 78–but mid to upper 60s lakeshore.