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  • Tim McGill

Weather Whiplash

From One Extreme To Another

It was nice while it lasted. Yesterday's high of 82° marked the 7th straight day with a high of 80° or more. That was the longest streak of summery warmth we have seen since late August last year.

A dramatic drop in temperatures begins today and hits a low point on Friday. Our 80s (or more) this past week has made it feel just like July and ranks among the warmest 10% of high temperatures for the last third of May. Our highs by Friday will fall into the lower 50s to rank among the coldest 10% of highs for this time of the year. We will be nearly 40° cooler Friday compared to Monday's high of 90°.

A brisk breeze off the lake and a warm front well south of the city will set us up for a wide range of temperatures this afternoon. Temperatures will be as cool as the lower 50s north of Chicago to near 80° well south of the city.

Winds will strengthen off the lake later today and by this evening will gust over 30 mph. Gusty winds will continue overnight and through the day on Friday. Our rain chances ramp up later this afternoon and stay high through most of Friday. The heaviest rain should fall overnight tonight (with some embedded thunderstorms) into early Friday morning.

So highs in the 60s today for most of us and then falling into the 50s tomorrow. The record cool high for tomorrow's date is 47° set in 1884. We won't break that record but we come uncomfortably close with a high around 52°. The meteogram below considers several different model forecasts of temperatures. It is onward and upward though after Friday through early next week. We will slowly but surely warm back well into the 70s by Monday. The average high for this time of the year is 74°.

The GFS model forecast temperatures for Friday afternoon looks like something we typically see in the middle of March. The model has temperatures falling into the lower to middle 40s or around 30° below average. There may even be some patchy frost Friday night into Saturday morning north and west of Rockford.

The temperature anomaly forecast continues to show the core of the anomalously cool air will be centered over Chicago and the Midwest on Friday. Much of the plains, Midwest, Ohio Valley and northeast will experience temperatures between 10° to nearly 30° below average.

Blame It On The Lake

Our brisk breeze off the lake will be the main culprit for the cooler pattern that begins today. Southern Lake Michigan's water temperatures are mainly in the middle to upper 50s near the shoreline but fall into the lower 50s out over the center of the lake. Gusty winds will be sweeping onshore off that cool water today and tomorrow. The winds lighten over the weekend but still blow off the lake to keep us about 5° to 10° cooler along the lakefront through Memorial Day.

The stronger winds today, tonight and tomorrow will whip up some large waves along our lakefront. Waves will build up to 6 feet today and up to 11 feet tonight.

The National Weather Service has issued a beach hazards statement that will be in effect from 1 am tonight until 7 pm Friday evening. In addition to big waves there will also be some dangerous rip currents. Rip currents were found to be the most frequent cause of weather related fatalities for portions of Michigan, Indiana, along with parts of the east, west and gulf coasts in a study that spanned the period of 1999 through 2018.

Putting A Dent In Our Drought

My last upate on the drought was posted on Friday. I will update our drought conditions tomorrow. Nearly 3% of northern Illinois is in a severe drought. O'Hare is now down 2.55 of rain below average for May and a whopping 6.79" below average since March 1st.

The GFS model is suggesting our best chance for some substantial rain will come with showers and thunderstorms developing late today and continuing on and off through Friday.

The GFS model total rainfall forecast through Friday afternoon has most of the area picking up at least around an inch of rain but some spots from the city and southward receiving nearly two inches of rain.

Temperatures Trending Warmer

We have a couple of considerably cooler than average days ahead but looking longer range the outlook is for warmer weather to return. The 6-10 day forecast favors us for about average temperatures overall from June 1st through June 5th. The 8-14 day temperature probability forecast favors us for above average temperatures overall.

The even longer range Subseasonal Experiment (SubX) temperature anomaly forecast is favoring the Chicago area for near normal temperatures for the middle of next month. The average highs for this period are in the upper 70s to lower 80s. The temperature anomaly forecast for the week ending June 11th has us outlooked for about average temperatures overall. The forecast for the following week ending on June 18th also has Chicago outlooked for about average temperatures overall.

Trending In Right Rain Direction

It's not a strong signal but it is pointing the in the right direction for some rain. We need all the help we can get considering our drought situation. The latest 6-10 day forecast has Chicago favored for near normal precipitation from June 1st through June 5th but the longer range 8-14 day forecast has favored for above average precipitation overall from June 3rd through June 9th.

Here is my 7 day forecast:

Today: Mostly cloudy, breezy & cooler, showers develop late High: 63 (58 lakeside)

Friday: Cloudy & cooler, on & off showers, breezy Low: 49 High: 52

Saturday: Mostly sunny Low: 48 High: 64 (56 lakeside)

Sunday: Partly to mostly sunny Low: 51 High: 71 (59 lakeside)

Monday: Partly to mostly sunny Low: 54 High: 75 (66 lakeside)

Tuesday: Partly to mostly sunny, spotty shower possible Low: 54 High: 74 (cooler lakeside)

Wednesday: Partly to mostly cloudy, scattered showers Low: 55 High: 76



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