Hoosier

Oh look, there's the polar vortex.

Yeah, you could say that. This was my 2nd 2" snow this season, but still waiting for a 3" snowfall. I'll have to decide whether to be generous and count whatever falls from the lake toward the storm total or as a separate entity. Temporally, it's a pretty large break in the snow here.

I got 2". It snowed good at times but just didn't last long enough. Probably a good chance to beat that total with the lake effect stuff later on but we'll see.

Saw some 14" reports in Nebraska and Iowa. Not sure if there's anything higher to this point.

Why, why, why

Since we can always take the medium range guidance to the bank... Anyway, looks like the next trackable storm for the sub. Besides the snow, the progged strength/position of the surface high could offer up an icy transition zone.

Nice band coming through.

What is the consistency of the snow like there?

Some places out that way are down to 1/4 mile visibility with fairly light winds. Must be pouring snow.

Precip has started.

I believe RC mentioned this in his afd last night. Notice the more showery/convective look to the echoes as the dry slot approaches. Question is how much it can swing into areas cold enough aloft for snow.

At least it's looking like the lake effect will be quasi-stationary/wobble around the city and nearby as we get into Tue/Wed. Still would appear to me that it could tack on an additional 2-4" (maybe locally higher) in some areas late Tue-Wed.

Why wouldn't it? The Euro always holds serve in the med range.

Interesting to see 31 and zr at IND while it's 34 with light rain at LAF, which is farther north. Precip timing/duration so far probably playing a role.

How's the Nebraska part looking (I haven't checked)

Temps are actually slightly above freezing in much of the southern 1/3 to half of the LOT cwa. Obviously will change later when precip picks up and also having the surface low track well south.

Gonna back off a bit on the synoptic call. Originally went 6-8" but now I'd go 5-6" imby. As far as the lake effect Tuesday night/Wednesday, prelim guess on that is 2-4". So if both things work out, then it would be 7-10" by the end of Wednesday which would be delightful given how things have been going.

mimillman just blew a gasket

A couple things about this. 1) posting consecutive 6 hour snow accum maps isn't very useful 2) that isn't even the latest run. It is the 12z run

Evening update from RC Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 1055 PM CST Sun Jan 24 2021 .UPDATE... 1015 PM CST The main tweak to the forecast for Monday-Tuesday winter storm was a bit of an upward adjustment in ice accumulations for areas near and south of the Kankakee River. No changes were made to the going winter headlines. It`s possible that the snow starts a bit later for portions of northern Illinois, more after sunset than prior to it, but again didn`t change start time of any of the headlines. Our burgeoning storm system can be seen getting going on water vapor imagery this evening. Another feature of note is strong drying with a jet streak racing from Mexico into southwest Texas. This dry air will be located at and above 500 mb and could be a wild card in the snow on Monday evening. The overall flavor of this storm system has changed due to an earlier intensification and occlusion process, with ingredients maxing out over the central Plains and into parts of Iowa. There`s still favorable moisture and forcing to get into moderate to even heavy snowfall rates late Monday into Monday evening, but with the synoptic system gradually weakening, and also some of the moisture probably shunted southeast by expansive convection south of the OH River, models have steadily and slowly backed off on QPF. Turning back to the h5 dry air wild card, it is one because also being advected northeastward with this air mass aloft is very steep mid and upper level lapse rates (7.5 to 9C/km above 550 mb). While some forecast soundings show the DGZ not fully saturated due to that h5 dry air, the potential for convection (slantwise or upright) given such impressively steep lapse rates aloft makes it difficult to predict how it will play out. Could make a case for lower snow ratios and less efficient accumulation, but if convection breaks out, that could quickly saturate the entire DGZ and cause heavier snowfall. All in all, didn`t make any appreciable changes to the snowfall amounts and going message, though aside from lake enhancement, possible that some parts of the area end up on lower side of the range offered in the WSW. A warm nose aloft (around 850 mb) is still progged to lift into the southern 1/3 or 1/4 of the CWA, so would expect a changeover to freezing rain in parts of our far south, probably with a narrower zone where sleet is probable in between the freezing rain and snow areas. Another thing to watch is the northward progress of a 700 mb dryslot, which would scour out ice in the DGZ and could change areas over to a freezing drizzle for a time late in the evening into the overnight. Favored for this potential would be south of I-88. Looking ahead into Tuesday, latest guidance coming in supports prolonged period of light to moderate snow on Tuesday under mid level forcing, with lake enhancement into northeast Illinois. Noting that lake effect parameters do get more favorable after synoptic snow winds down later Tuesday, with a signal that there could be accumulating lake effect snow for portions of northeast Illinois and perhaps extreme northwest Indiana all the way into Wednesday, which the midnight shift will assess. Castro

Nice slow movement of the lake plume on the RAP

Fwiw, I agree with this take. I'm not the met of course but do have a lot of years watching this kind of thing. None of the parameters are jump off the page stuff, but certainly good enough for accumulating lake effect snow on Wed. Looks like delta T could eventually get to around 16C or 17C amidst modest inversion heights and decent omega overlap in the DGZ. Exact location still tbd but it looks like it could hang around somewhere for a good number of hours.

Yeah, plume kinda stalls out here on Wednesday. I had been favoring the IL side for it so will have to dig into it more.

I just realized that maps is spam spelled backwards.

Interesting stalled northward progression of precip in IL/IN between 18z and 21z