Warm-up ahead, but weekend cool-down looms
Warming ahead, but temps take a dive over the weekend
Frost and Freeze advisories were hoisted for Tuesday night into early Wednesday for much of the Chicago area, with temps in the 20s expected away from the lake—but sunshine returns “big time” Wednesday and warming follows Thursday and Friday especially away from lake Michigan—but a powerhouse 180 mph jet stream wind max over the Gulf of Alaska is to dive into nation’s mid-section spinning up a chilly late season upper low this weekend into next week with lots of clouds and showers
VIEW SLIDESHOW OF THE UPCOMING CHANGES:
A cold Tuesday night-Wednesday a.m. with freezing temps at O’Hare for only the 5th time this month as inland low temps dip into the mid to upper 20s at the coldest locations.
The nighttime chill followed a day which saw wet flakes of snow mixed with morning rain showers—something (i.e. snow) that’s happened on April 25th only 7 of the past 138 years dating back to 1885, the year our official Chicago snow records began. The most recent April 25th snowflakes occurred 7 years ago in 2016.
The frost and freezing temps Tuesday night also followed a day in which temps failed to make it out of the 40s. Daytime temps THAT CHILLY have’t been regular occurrences on April 25th’s here. In fact, only 33 of the 151 April 25’s for which we have records (our official temp record goes back further than the snow record here—all the way back to 1871)—that’s just 22% of them—have produced highs which have failed to break above 50-degrees.
Despite Recent Chill. April 2023 To-Date Ranks Among Warmest on Record…
WHAT’S INTERESTING—AND YOU MAY FIND THIS SURPRISING GIVEN THE RECENT CHILL HERE—IS THAT APRIL, 2023 ACTUALLY RANKS AMONG THE WARMEST 6% OF ALL APRILs TO DATE since the early 1870s. IT’S THE 9th WARMEST APRIL OF THE PAST 151.
Above normal APRIL 2023 average daily temps have outnumbered ones which have finished colder than normal 14 to 11. And for 2023 to date, the dominance of warmer than normal days is even more striking. Chicago has experienced ABOVE NORMAL DAYS since Jan 1 at more than twice the pace of below normal days—75 to 35 respectively–with 4 days coming in “normal”.
Late-Week Reprieve From The Chilliest Temps Won’t Last
A STUBBORN COLD, UNSETTLED UPPER AIR LOW PRESSURE SYSTEM, HEMMED IN AND THEREFORE SLOW MOVING AND LIKELY TO LAST FOR DAYS HERE–IS TO TAKE SHAPE OVER THE WEEKEND
HERE’S A LOOK HOW OUR COMPUTER MODELS ARE DEVELOPING THE CLOUDY WEEKEND COLD AIR POOL ALOFT. This is the forecast for 7a.m. CDT FRIDAY through 7 a.m. CDT Wednesday:
Instrumental to the development of this STUBBORN CENTRAL U.S. UPPER LOW is a 180 mph jet stream speed max making its way across the Gulf of Alaska toward British Columbia in western Canada. Once ashore, these powerful high altitude winds will plunge southward into the Plains spinning up a cold upper low pressure which is to become trapped in a complex blocking pattern which will, for all intents in purposes, lock it in place well beyond this weekend–very possibly into the middle part of next week. That means a whole set of days dominated by clouds, unseasonably chilly temps and sporadic showers.
THIS SEQUENCE OF PREDICTED SURFACE WEATHER MAPS tracks the predicted development of a broad low pressure over the Midwest
This panel is the forecast for 7am CDT Saturday through 7am CDT Tuesday morning
THE GOOD NEWS IS there continue to be indications of a temp rebound to something closer to normal late next week with daytime highs within striking distance of 70 a good bet.
MAY 2023’s ONLY 5 DAYS AWAY—IT BEGINS NEXT MONDAY—LIKE ITS PREDECESSOR—MAY IS A STUDY IN CONTRASTS WEATHER WISE
In looking over the records, I’ve found a trace of snow has occurred in a quarter of the past 151 Mays for which we have records—that’s 48 of the Mays since 1873. Fortunately, only 8 of the 48 have produced “measurable” snow—defined at 0.1″ or more. And measurable snow doesn’t stick around in May.
But while SNOW CAN OCCUR–SO CAN WARM, EVEN HOT WEATHER: 135 of the past 151 Mays have generated 80-degree high temps—and 45 of the 151 Mays have even produced 90s. So hang in there warm weather enthusiasts. It may not seem like it—but nature has the Chicago area on a track toward warmer days to come. With a chilly lake next door, it takes a bit of time some years.