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Hoosier

September 2017 Record Breaking Heat Wave

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The CR airport was able to shoot up to 93 in early afternoon yesterday, perhaps the highest in the state.  The morning storms over southeast Iowa cleared out the high dews for awhile (upper 50s/low 60s through midday), enabling the temp spike.  By 2pm the dew surged into the upper 60s and the temp responded by falling to the upper 80s.

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3 hours ago, cyclone77 said:

Noticeably cooler in that strip that got dumped on with heavy rain the other night.  Only upper 80s along that strip.

Noticed that last night.  Wasn't sure if it was a coincidence or if it's capable of picking up on localized zones of recent heavy rains like that.

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2 hours ago, beavis1729 said:

UHI is a huge pet peeve of mine.  Not worth diverting the thread...but there is something wrong when humans can alter their environment so much that temperatures can vary by 15+ degrees in two similar locations with the same airmass.  You most often see this in late season heatwaves (like now), or sunny late fall days (when temps drop like a rock in rural areas but stay up in urban areas due to residual warmth from the sunlight), or of course winter days with snow cover.

Anyway...I was shocked at how warm it got at ORD yesterday.  It was partly/mostly cloudy nearly all day, yet still hit 94...on September 21 no less.  The only explanation I can think of is "left-over" UHI (warm start - low temp of 72), combined with mixing in the afternoon that resulted in lower dews around 60.  Dry ground too?  Winds never exceeded 10 mph...and you'd have thought that strong S/SW winds would be needed to create such warm temps.

If the mixing occurs again today and skies remain mostly sunny as they are now...then, despite slightly lower temps aloft, you'd have to think ORD will hit 95 today.  Time will tell.

I think you covered it.  Urban effects and dry ground probably helping to squeeze every last ounce out of the low level warming.  95 looks like a pretty good possibility.  Already upper 80s on the 5 minute obs.

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I think you covered it.  Urban effects and dry ground probably helping to squeeze every last ounce out of the low level warming.  95 looks like a pretty good possibility.  Already upper 80s on the 5 minute obs.

 

89 on 15z ob, vs. 87 yesterday. I agree 95 is a decent bet today. 850 and 925 mb temps are *slightly* cooler than yesterday, but factors already mentioned and lack of cloud cover should enable 95 to happen. I wouldn't be shocked if it ends up 94 again as well with ever so slightly cooler thermal profiles but with trends so far, 95 appears more likely.

 

Edit: ORD reached 90 as of 11:15am.

 

 

 

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26 minutes ago, RCNYILWX said:

88 on 15z ob, vs. 87 yesterday. I agree 95 is a decent bet today. 850 and 925 mb temps are *slightly* cooler than yesterday, but factors already mentioned and lack of cloud cover should enable 95 to happen. I wouldn't be shocked if it ends up 94 again as well with ever so slightly cooler thermal profiles but with trends so far, 95 appears more likely.

Sent from my SM-G935V using Tapatalk
 

Yeah, and the cooling aloft is so slight like you said...basically fractions of a degree C compared to yesterday.

Was wondering if ORD was going to tie/break the record high min from today, but it cooled off just enough.

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It's no secret that the location of the official observation site has had an effect on Chicago's climate record.  Like, when the official site was in/close to downtown, days that had lake breezes would result in lower max temps than areas farther away from the lake.  

But 95 degree heat is a rare thing this late in the calendar year, no question.  For some comparison, I looked at a few other cities that are well inland.  Rockford has only one 95 degree day on/after September 22. South Bend has done it 3 times.  Even St. Louis has only done it 3 times in their recorded history.  Even more impressive to be getting it into central Michigan.

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It's no secret that the location of the official observation site has had an effect on Chicago's climate record.  Like, when the official site was in/close to downtown, days that had lake breezes would result in lower max temps than areas farther away from the lake.  

But 95 degree heat is a rare thing this late in the calendar year, no question.  For some comparison, I looked at a few other cities that are well inland.  Rockford has only one 95 degree day on/after September 22. South Bend has done it 3 times.  Even St. Louis has only done it 3 times in their recorded history.  Even more impressive to be getting it into central Michigan.


Only 3 95+ days after this date at STL is very surprising.

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Have been looking at other notable stretches of heat in the fall in Chicago and the one that stands out most to me is October 1953. 8 consecutive 80s from 10/15-10/22. Considering low sun angle and hours of daylight, that's wildly impressive. That was coming on the heels of 99° on 9/29/1953 and also 10/2/53 reached 90.

The next longest streak of 80s entirely within October is 6 from 10/4-9/1939. More recently we had 5 80s in a row on 10/5-9/2011 10/4-8/2007.

This is not to diminish the current stretch of heat but it does give some context vs. the completely unprecedented heat in March 2012.

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2 minutes ago, RCNYILWX said:

Have been looking at other notable stretches of heat in the fall in Chicago and the one that stands out most to me is October 1953. 8 consecutive 80s from 10/15-10/22. Considering low sun angle and hours of daylight, that's wildly impressive.

The next longest streak of 80s entirely within October is 6 from 10/4-9/1939. More recently we had 5 80s in a row on 10/5-9/2011 10/4-8/2007.

Sent from my SM-G935V using Tapatalk
 

Yeah, that October 1953 stretch is nuts. Came after that 99 degree high that year on 9/29.

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8 minutes ago, beavis1729 said:

Crazy that ORD is already 89 at 11 AM, and there hasn't even been any mixing yet.  Dew is still elevated (67).

Now up to 91. 

Seems like a stronger low level flow today, so any threat of a lake breeze moving that far inland seems to be gone.

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Had to pop in for this record event.. Can always appreciate these meteorological record events no matter hot or cold or whatever..

 

Already was up to 92 at 1 which is a new record high. The old record was 91 set back in 1895!

 

Yesterday it hit 93 here at KBTL which was also a new record high.

 

Just a fyi but the models have been running a bit cool for daytime highs so i would add a few to whatever they say.. Been this way for a while.

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Somewhat bewildered that ORD and/or MKE haven't issued heat advisories.  Perhaps the technical criteria haven't been met...but when it's out of season, there should be additional considerations...similar to being more lenient on the first winter weather advisory for the first snowfall of the season. 

I believe Las Vegas and Phoenix WFOs have different Heat Advisory/Heat Warning criteria depending on the time of year.

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So far, the max temp for 2017 at ORD has been 95 (on June 12).  If it hits 96 today, it would be the latest in the season that an annual max has ever occurred.  Previous latest date was September 14 (in 1893, 1915, 1927).  I'm honestly surprised that it has actually occurred in September before.

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1 minute ago, beavis1729 said:

So far, the max temp for 2017 at ORD has been 95 (on June 12).  If it hits 96 today, it would be the latest in the season that an annual max has ever occurred.  Previous latest date was September 14 (in 1893, 1915, 1927).  I'm honestly surprised that it has ever occurred in September before.

 

We did that here yesterday.. The highest was 92 back on June 12th..

 

Not sure what the record for that is here?

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3 minutes ago, Harry said:

 

We did that here yesterday.. The highest was 92 back on June 12th..

 

Not sure what the record for that is here?

Good question.  I have to imagine that 9/21 is now the new record latest "annual max" date for your area.

I got the Chicago numbers from NWS LOT; they created a page with this info.

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Somewhat bewildered that ORD and/or MKE haven't issued heat advisories.  Perhaps the technical criteria haven't been met...but when it's out of season, there should be additional considerations...similar to being more lenient on the first winter weather advisory for the first snowfall of the season. 

I believe Las Vegas and Phoenix WFOs have different Heat Advisory/Heat Warning criteria depending on the time of year.


I wouldn't agree that it's really that much out of season, considering we just switched over to astro fall today, which is what most non-weather following people go by.

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53 minutes ago, Hoosier said:

Probably even more impressive than what the high ultimately ends up at is that LOT tweeted that it was already 90 at ORD at 11:15.  

 

My truck had 91 on the west end of my road  and 90 going by house on the east end and that was also around 11:15.  Not a lot of breeze out there today  until now where it feels like it wants to flip off the lake some finally.  Scorcher for sure.

 

gd1Yoqw.jpg

 

 

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Madison with another record today.  Up to at least 91, will have to see if there was an intrahour bump.  Would again be the latest in the season that we've hit 91 or above.

 

Some beautiful July weather outside.

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