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  • Tim McGill

Northern Illinois' First Tornado Touchdown Of 2021

Western Suburbs Hit Hardest

Daybreak this Monday revealed the damage from at least one tornado that touched down southwest of Chicago late last night. The National Weather Service issued this summary of the storm reports from last night and early Monday morning.



Tornado warnings were issued just before 11 pm Sunday night. The worst damage has been reported from Naperville to Woodridge and on into Darien. The tornado touched down a little after 11 pm. At least five people were injured in the storms. There were a total of six areas of concentrated damage. Some of them also included notable rotation on doppler radar.



The National Weather Service confirms the damage in the Woodridge, Darien an Burr Ridge area was from a tornado. This storm was accompanied by a a "tornado debris signature". This is sometimes referred to as a "debris ball". It is a signature on doppler radar that indicates debris being lofted into the air from a tornado.


The graphic below show one of two tornado warnings that were issued for the area around 10:45 pm last night. It appears the twister's path stretched from Naperville to near Burr Ridge.


The National Weather Service will survey the damage today to determine the strength of the tornado. Early estimates of the winds are over 100 mph. It is possible this was either an EF-1 or EF-2 tornado on the Enhanced Fujita Scale.


I posted a few weeks ago about our quiet start to the severe weather season. The storms last were the strongest yet this year here with the first confirmed tornado for northern Illinois of 2021.






No More 90s This Week

The heat and humidity that fueled last night's storms were triggered by a cold front that will kick in a cooler and more quiet pattern for the next couple of days. Saturday’s high of 90° means we now have 9 days this year when the high was 90° or hotter. That is more than half the average # of 90°+ days per year we typically see and there is still plenty of summer left.


No more 90s this week. The HRRR model has our highs today only topping out in the upper 60s and lower 70s today. That is around 10° to 15° below average for this time of the year. Average highs for today's date are around 82°.


Dew points are the preferred measurement of moisture for meteorologists. They were well into the 60s over the weekend by will continue to fall from the 50s early today to the 40s by the afternoon. It will feel like fall with the cooler and more comfortable conditions expected through Tuesday night.


Watch for gusty northwest winds today that will deliver this much cooler air. The winds diminish tonight and with mainly clear skies we will fall into the 40s well west of the city.


The next threat of rain comes late Tuesday night into early Wednesday morning.


The National Blend Of Models has highs slipping into the 70s today and Tuesday. We bounce back to more seasonable warmth for the middle of the week before cooling off again early this weekend. No extreme heat and humidity expected for the next at least eleven days.



Tonight will be the coolest night we may see for the rest of this summer. The GFS model has lows falling into the middle to upper 40s in our northern, far western and southwestern suburbs.



The GFS model temperature anomaly forecast has us around 10° to 15° below average by for Tuesday morning. Average lows for Tuesday are around 63°. The Chicago area and Midwest will have some of the greatest temperature departures from average early Tuesday for the entire country.



A cooler than average pattern could continue through the start of July. The 6-10 day forecast has outlooked us for below average temperatures overall from June 26th through June 30th. The longer range 8-14 day forecast also favors us for below average temperatures overall from June 28th through July 4th. Average highs for late June and early July are in the lower to middle 80s.



The even longer range Subseasonal Experiment (SubX) temperature anomaly forecast favors us for above average temperatures overall for the first half of July. The average highs for this period are in the lower to middle 80s. The temperature anomaly forecast for the week ending July 9th has us outlooked for above average temperatures overall. The forecast for the following week ending on July 16th also has Chicago outlooked for above average temperatures overall too. It takes a close look at this second map to see we are the exception for Illinois. Most of the state is outlooked for about average or below average temperatures.





Storms Brought More Drought Relief

O'Hare officially picked up 1.85" of rain on Sunday. That was enough to now move the month's total to the surplus side. We are now up .81" above average for June rainfall. We are still down over six inches of rain below average since March 1st.


Here is a recap of my post from last week with details on our drought that does not include the recent rain:


Our ongoing drought in northern Illinois has both deepened and expanded according to the latest analysis from the US Drought Monitor. Almost 3% of the region is now in an extreme drought for the first time this year. That's the third of four levels of drought with "exceptional" being the fourth or worst level. 6.43% of Illinois is now in a severe drought (up from 4.58% last week). 9.18% of the state is in a moderate drought (up from 8.52% last week). The worst of the drought is centered in the northeast corner of the state and includes most of Lake County, all of McHenry county and portions of Cook, Kane, DeKalb and Boone counties. This does not take into consideration the rain that fell Thursday night into Friday morning.



Last Friday's post also included a look at Wisconsin, the Midwest and where the drought is hitting hardest, the western states. I'll have an update on our drought and the latest analysis from the U.S. Drought Monitor in this Friday's post.


The GFS model brings in some spotty showers for Tuesday night into early Wednesday. The next decent chance of rain arrives late Friday and continues into Saturday.



The GFS model total rainfall forecast for our next round of rain late Tuesday into Wednesday squeezes out just a tenth of an inch to nearly a third of an inch of rain for most of us. Higher amounts of more than a half inch are expected well west of Chicago.


The long range precipitation probability forecasts are a mixed bag for the end of June and start of July. The latest 6-10 day forecast has us outlooked for below average precipitation overall from June 26th through June 30th with the Chicago area. The longer range 8-14 day forecast also favors us (slightly) for above average precipitation overall from June 28th through July 4th.





Here is my 7 day forecast:


Today: Mostly cloudy, breezy, cooler High: 72


Tuesday: Mostly sunny Low: 53 High: 74


Wednesday: AM shower?, partly to mostly sunny Low: 59 High: 81


Thursday: Partly/mostly cloudy, sct. showers/t-storms late Low: 63 High: 85


Friday: Mostly cloudy, sct. showers & t-storms Low: 69 High: 82


Saturday: Partly/mostly sunny, sct. shower/t-storms possible Low: 64 High: 77 (cooler lakeside)


Sunday: Partly/mostly sunny, shower possible late Low: 62 High: 82 (cooler lakeside)


#ilwx

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