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Unseasonably cool in Chicago Thursday—While Winnipeg, Canada reaches 90 degrees

Contrast the cool weather here thanks to a persistent NE flow off the lake to the 90 degree heat at Winnipeg, Canada.  Only one May 25th in Chicago over the past 20 years has been any cooler: 57 degrees on May 25, 2013.

Memorial Day Weekend Outlook and beyond

A blocking pattern aloft traps the current high pressure over the area well into next week. As its winds, still expected to blow off the lake and keep us cool Friday, weaken in coming days, the air mass will begin to warm in place through the upcoming Memorial Day holiday weekend.

Predicted Chicago Temperature Departures From Normal:

• There are also indication northeast surface winds may lock in the weekend which follows next week produce a downturn in temps after the warmth predicted the middle and end of next week.

It’s official—today’s “Drought Monitor”, our country’s seminal measure of drought and dry weather, analyzes a swath of the Chicago area as being in a state of “MODERATE DROUGHT”

The last significant rain in the city occurred more than a month ago (1.17″ on April 3-5).

• A modest increase in humidities the back half of next week could lead to some late week showers and t-storms.

Opening Stages of a Flash Drought

What’s been happening on the precipitation front over the vast majority of the Chicago area is characterized as the opening stages of a FLASH DROUGHT. And with today’s release by the National Weather Service and USDA of the DROUGHT MONITOR—the official measure of drought and dry weather in the U.S.—a state of MODERATE DROUGHT has been assessed over much of Cook and sections of DuPage and northwest Will counties.

Heavy Rains In The Past 2 Weeks

It’s a fact BIG RAINS fell in hail and lightning generating t-storms over areas just south of Chicago in the past two weeks. Those storms unleashed rainfalls as high as 3.80″—but the area hit drenching rains was very localized. Those rains—like so many of the past 6 to 7 weeks have bypassed much of the Greater Chicago area.

In Chicago, O’Hare rainfall to date in May, 2023 is a meager 12% of normal–just 0.42″ of the normal 3.54″ to date. Assuming an additional 0.16″ doesn’t fall through the end of the month which occurs at midnight next Wednesday, this May will go into the books at the 2nd driest of the 153 Mays on the books here since 1871.

December-February Precipitation

Interestingly, while Dec, Jan, Feb and March each posted precip surpluses, 8 of the past 12 months have generated sub-par precip totals in Chicago.

THE AREA IN WHICH APRIL & MAY PRECIP HAS LAGGED HISTORIC NORMS is quite widespread across the Midwest.

Will the Moisture Deficit Continue?

Modeling suggests an increase in rain chance the back half of next week, but the estimated 15-day total precipitation by computer model runs, current forecast trends suggest the overall SUB-PAR PRECIP TREND may continue. So all eyes in coming weeks and months will be on how future rains lay out. Here is the 6-10 and 8-14 Day Precipitation Outlook: