Hoosier

A walk down memory lane from January 30.

IGQ right behind at 92/81 ORD is a virtual lock to not drop below 80 overnight, but it would take the ultimate magic act to get it to hold through all of Saturday.

Was outside a little while ago and it actually didn't feel quite as oppressive as I thought it would. I think the wind helps the comfort level to some extent. You put 90/80 in calm conditions and that is going to have a different feel, which is what that WBGT index or whatever it was called that LOT posted about the other day was factoring in.

Given where temps were around midnight, I thought it might sneak down to 79, at least intrahour. Really shows the kind of airmass... not only warm but extremely moist. Even here it didn't drop below 80. Convection tomorrow brings some uncertainty but there is a legit possibility that tomorrow ends up being the hottest day.

After a high of only 87 yesterday. Pretty impressive.

Muggy as all get out. Still fairly widespread dewpoints in the upper 70s and even some low 80s at midnight central.

So I guess the next question is will the high only being in the 80s cost a chance of putting up an 80 degree low. It won't have all that far to drop but 925 mb temps are progged to stay up around 80F through the night. Along with some wind remaining and the urban environment, it should still be close imo... barring some new convective outflow rolling through.

The recovery is off to a good start, at least better than I thought. Winds have flipped southerly and a little gusty. If it can get into the mid 80s around 3 pm, then perhaps 90 could be in reach.

Besides the marginal thermal profiles aloft, here's another reason to be skeptical of ORD hitting 100 tomorrow: there has been over an inch of rain today. I went back and looked at the previous 100 degree days, and none of them had so much rain the day before. Zero. The most rain on a day before hitting 100 was 0.28" on 7/5/2012, and then it hit 103 on 7/6/2012. Would point out one close call happened in 1988... there was 1.52" on 7/30/1988 and then it reached 100 two days later.

Time to see how big the rally is. ORD should make the mid-upper 80s I think. Not sure about anything warmer than that though.

HRRR really puts a dent in highs tomorrow in northeast IL, due to convection lingering into the afternoon. Storms look fairly likely to occur, so I think it's more a question of timing. If it gets out during the morning, then it will have no trouble shooting into the 90s. If they persist into afternoon, then all bets are off.

LOT now has 99/80 forecast for the high/low at ORD on Friday, which is very close to putting it in some elite company. I mentioned there have been 8 days with a high of 100+ and low of 80+ for Chicago. Here they are. 7/5/1911: 102, 82 7/27/1916: 100, 82 7/30/1916: 102, 84 8/6/1918: 101, 82 7/10/1936: 102, 80 7/13/1995: 104, 81 7/14/1995: 100, 83 7/6/2012: 103, 82

I bet you will hit 100 even if Chicago doesn't.

Cheater.... it's already 4:45 in Detroit.

LOT upgraded to warning for the vast majority of the cwa URGENT - WEATHER MESSAGE National Weather Service Chicago IL 214 PM CDT Wed Jul 17 2019 ...A PERIOD OF DANGEROUS HEAT EXPECTED ACROSS NORTHERN ILLINOIS AND NORTHWEST INDIANA... .A multiple day episode of dangerous heat is expected Thursday through Saturday. There is a potential for showers and thunderstorms Thursday morning that may keep Thursday cooler than forecast, especially in the morning. However confidence is increasing that dangerous heat will arrive later Thursday afternoon and peak in intensity on Friday. Additionally, there will be little relief from the heat overnight Thursday and Friday. The urban heat island core of Chicago is most susceptible to night time temperatures that do not cool significantly, limiting the amount of relief that can occur at night. ILZ010>014-019>023-032-033-039-INZ001-002-010-011-019-180315- /O.UPG.KLOT.EH.A.0001.190718T1700Z-190721T0000Z/ /O.NEW.KLOT.EH.W.0001.190718T1700Z-190721T0000Z/ Lee-De Kalb-Kane-DuPage-Cook-La Salle-Kendall-Grundy-Will- Kankakee-Livingston-Iroquois-Ford-Lake-Porter-Newton-Jasper- Benton- Including the cities of Dixon, DeKalb, Sycamore, Aurora, Elgin, Naperville, Wheaton, Downers Grove, Elmhurst, Lombard, Carol Stream, Addison, Chicago, Humboldt Park, Hyde Park, Lakeview, Lincoln Park, Logan Square, Navy Pier, Ottawa, Streator, Peru, La Salle, Mendota, Marseilles, Oswego, Boulder Hill, Yorkville, Plano, Morris, Coal City, Minooka, Joliet, Bolingbrook, Kankakee, Bourbonnais, Bradley, Pontiac, Dwight, Fairbury, Watseka, Gilman, Onarga, Paxton, Gibson City, Gary, Hammond, East Chicago, Merrillville, Portage, Valparaiso, Chesterton, Roselawn, Kentland, Morocco, Goodland, Brook, Rensselaer, DeMotte, Fowler, Otterbein, Oxford, and Boswell 214 PM CDT Wed Jul 17 2019 /314 PM EDT Wed Jul 17 2019/ ...EXCESSIVE HEAT WARNING IN EFFECT FROM NOON CDT THURSDAY TO 7 PM CDT SATURDAY... The National Weather Service in Chicago has issued an Excessive Heat Warning, which is in effect from noon CDT Thursday to 7 PM CDT Saturday. The Excessive Heat Watch is no longer in effect. * HIGH TEMPERATURES...Peaking well into the 90s each day, with Friday and Saturday potentially in the upper 90s to near 100 degrees. * MAXIMUM HEAT INDICES...Peaking 104 to 114 each afternoon. * LOW TEMPERATURES...Lows only in the upper 70s to near 80 on Thursday and Friday nights will offer little to no relief from the heat. * IMPACTS...The cumulative effects of temperatures and heat index values this high could lead to heat related illnesses with prolonged exposure. Those without air conditioning, elderly, small children, and pets are especially susceptible. Plan ahead. Have a cool place to shelter from the heat. Avoid outdoor activity, especially strenuous ones, during the peak heating times of the day.

OT but I know the people killed in this plane crash. Identities haven't been released yet but the last name is Weaver. The dad and sons were killed. Very sad. https://amp.cnn.com/cnn/2019/07/16/americas/canada-plane-crash-missing-people/index.html

Yeah 99 is a real concern. Progged 850 mb temps are a bit marginal for 100. Hopefully a very warm start to Friday can help to compensate even just a little. I noticed the 3 km NAM wants to bring some convection through Thursday night/early Friday, which would have some impact on the low temp/starting point on Friday. Not a high probability scenario but something to keep in mind.

First of all, you can't get the same level of crazy anomalies in summer like you can in winter. Just not possible. But even after accounting for that, the arctic outbreak was more impressive for the most part. We can look at return rate, and the return rate for that would be longer than the return rate for the upcoming heat wave.

If ORD gets 99'd Will be interesting to see what happens tomorrow. Guidance does indicate a pretty stout recovery even with convective concerns.

LOT did issue an excessive heat watch for Chicago. I can't remember what Cook county criteria is but I know it is different than the rest of the cwa.

A trace? Maps must be deceiving because I was just looking at a July precip map and nobody in N IL was that dry.

Never heard that term either. I like this Carlaw person. They usually have pretty decent afds. 98/79 in the forecast for ORD on Friday. Getting close to the magic numbers.

I don't think that works for central IN. The hottest days are going to tend to have west or southwest flow, and there are no large lakes in those directions.

Yeah it's interesting. I think being a bit farther away from the source region of these airmasses plays a role. This upcoming heatwave doesn't really strike me as one of those where everybody between Moline and Chicago is going to reach 100. I think it's a bit too marginal. The UHI around Chicago could give enough of a boost to reach triple digits.

This is the Barry remnant. Although wind fields aloft are weakening, could have just enough shear for something. Wouldn't be shocked as it doesn't take much in these situations.