Hoosier

That Thanksgiving storm just hits a brick wall and can't gain any latitude on the 12z GFS, due to strong confluence in the northern tier and Canada. The 00z Euro had a much different type of setup though. We'll see what 12z has.

The 1978 storm usually gets talked about as an IN/OH/MI storm, and deservedly so, but it was no slouch in Chicago. Similar story for Milwaukee as they also received about a foot and of course accompanied by decent winds. The surface low trajectory and track were not ideal for those cities, but good enough, and I think the mid-upper level energy diving in as far west as it did (Iowa) probably helped those places.

Went back and looked at LOT's page for the July 1996 flood, and there's some newer info on there that I hadn't seen. There may have been an unrecorded maximum in excess of 19". Just phenomenal. Rainfall data was collected from hundreds of gauges to map the extent of the event. A contour map of rainfall published in a technical report created several months after the event is shown below (Angel et al 1997). In 2020, newer radar bias-correction techniques were used to create estimated rainfall maps using rain gauges and radar data combined. Updated analyses suggest that heavier rainfall than the recorded maximum may have occurred just to the southwest of Aurora. A large area experienced rainfall with less than a 1% chance of occurring in a given year.

Alek's already set the narrative with the futility record call. Now it's all about justifying it at every turn, even though it's only November.

I was in LAF then but I know it was bad in northeast IL/northwest IN. My mom's area flooded terribly. Like you said, places that would normally be ok had problems.

Could argue for LOT to pull the trigger on an advisory for Porter county with the afternoon package. Maybe they'll punt til later though.

West/southwest of the city are the winners so far with 2-3". Northern burbs may make up ground though.

What about a heavy rain/flood day? I'd probably go with Aurora day, July 18, 1996 or whatever it was. Didn't get nearly what they had but we had a lot of rain. I was at my friend's house and we wanted some snacks so we walked across town to a convenience store in the pouring rain. I guess this kid's mom wasn't home to give us a ride there... really don't remember that part.

You want to talk about a firehose on radar... that January 2002 storm was it. Just a ton of moisture.

Good God. Gonna have to start paying attention to this. And yes, welcome back Beau.

This will get wetbulbed down as precip moves in, but it gives a sense of the marine influence west of Lake Michigan

Definitely think that is the window to watch for the city proper. It's an extreme thread the needle though because they'll need to be perfectly positioned on the western end of the convergence area to take advantage of winds flipping more offshore, but not so much that the activity gets shunted quickly east.

Imagine this with a colder setup

Yeah, even more bullish than before.

I remember that one to some extent. I know it was colder than what Tue-Wed will be.

Thanks for the input. Went back and looked at that one. 850 mb temps were -10C, which is colder than what we'll have tomorrow into Wednesday. I can see why -10C with organized lake effect would be able to get heavy amounts pretty much up to the shore.

It's part science and part art when it comes to figuring out how much/how far inland for the marine influence. Warm lake = rain can definitely be overly simplistic. There are all kinds of factors that go into it, such as how cold the airmass is, lake water temps, exact wind direction, wind speed, precip rates. If we had 850 mb temps of -15C tomorrow, then Alek would be ripping snow with significant accumulations lakeside despite onshore flow and water temps of 50+. But we don't have that so it's a more nuanced picture as you move from lakeside to farther inland.

18z HRRR I guess the question for the downtown Chicago area is whether there will be a window where the convergence axis starts to shift eastward and flip winds offshore while still having some precip around. That is sort of being hinted at on Wednesday and may represent a little better opportunity for the core of the city, but overall the better place to be is inland.

Yeah I was talking LOT cwa.

Come on LOT, go with the HRRR. It sounds like you wanted to.

Tough call here. There's a scenario where if the lake cooperates that I could envision about 3-4", but that's probably near best case. More likely to be less than that, but whatever falls probably won't actually be what's on the ground because of melting in between.

For Chicago, this will be the first time since 2014 that the first measurable snow of the season comes less than 1 week after having a high of 70+ 10/27/2014: high 77 10/31/2014: 0.1" 11/10/2022: high 76 11/15/2022: tbd Fwiw, if 1" or more occurs, it would be the first time since October 1989 that the first measurable snow of 1"+ happened less than a week after having a high of 70+

That being said, I'd be pretty surprised if the highest amounts in the area aren't somewhere in a zone inland from Lake Michigan.

Models really picking up on the lake enhancement, and of course the HRRR is its usual happy self in that regard.

That's just what the model is spitting out.