Hoosier

Just starting to see signs of snow sticking to paved surfaces. Conditions should go downhill in the next hour or two as rates increase.

2021 barely eclipsed 30" of precip at ORD with 30.15". It was the driest calendar year since 2012.

Was it mild? Public Information Statement National Weather Service Chicago IL 1203 PM CST Sat Jan 1 2022 /103 PM EST Sat Jan 1 2022/ ...A Look Back at the Climate for the Month of December 2021 for Chicago and Rockford... At Chicago, the average high temperature was 45.8 degrees, which is 9.2 degrees above normal. The average low temperature was 30.2 degrees, which is 5.8 degrees above normal. The average temperature for the month was 38.0 degrees, which is 7.5 degrees above normal. During the month of December, 2.30 inches of precipitation were recorded, which is 0.19 inches above normal. 1.9 inches of snow fell, which is 5.7 inches below normal. Three daily records for Chicago were set during the month of December 2021: * Record daily maximum temperature of 66 degrees on the 15th. * Record daily highest minimum temperature of 50 degrees on the 15th. * Record daily maximum temperature of 66 degrees on the 16th. One top ten monthly record: ** 6th warmest December on record since 1871 with a mean average temperature of 38.0 degrees. At Rockford, the average high temperature was 44.2 degrees, which is 9.9 degrees above normal. The average low temperature was 25.7 degrees, which is 5.5 degrees above normal. The average temperature for the month was 34.9 degrees, which is 7.6 degrees above normal. During the month of December, 2.42 inches of precipitation were recorded, which is 0.49 inches above normal. 2.6 inches of snow fell, which is 6.8 inches below normal. Four daily records for Rockford were set during the month of December 2021: * Record daily maximum temperature of 69 degrees on the 15th. * Record daily highest minimum temperature of 50 degrees on the 15th. * Record daily maximum temperature of 68 degrees on the 16th. * Tied record daily maximum temperature of 55 degrees on the 24th. One top ten monthly record: ** 4th warmest December on record since 1905 with a mean average temperature of 34.9 degrees. $$ Ogorek

Snow is sticking a little more now on colder surfaces.

Only gonna get better. Delta T right now is likely only 12-13C

Having trouble even getting a coating on colder surfaces here to this point. I see some wisps of whitening.

Bottom layer of this is going to be heavy. Pavement already wet.

More of a T/Td spread at ORD/MDW than the other sites, so some room to cool. Also will help as CAA increases to help counteract the warmth coming off the 40+ degree lake.

Now it's snowing. Just need to cool off a little bit so it can stick.

Currently drizzly

Guess I'll go 8-10" here. Obviously counting on the lake to come though sufficiently to get to that. Btw, morning water temps are 43 Chicago shore and 42 at the crib.

Yes but it giveth and taketh away. Early season can be especially tough for areas too close.

Gonna be solid winter conditions in the city later tomorrow as the lake enhancement and stronger winds kick in. I definitely think some models are underplaying the lake component. Not that that should be too surprising as many of them are not really geared for that kind of thing. As far as I can tell, water temps are 40+ not just near the IL shore but pretty much all the way across the lake and also pretty far north as well.

Paragraph is below for anyone interested. This doesn't have to be a binary yes/no thing as far as convection having an impact. It can be no/little impact all the way up to big impact. For reasons that have been outlined, don't think it's *as* big of a problem as it could be in other types of setups. The overnight shift will continue a more thorough assessment of the upcoming snow event and evaluation of headlines including their timing. There will be a lot of convection in the warm sector Saturday morning into early afternoon, and that will have some robbing moisture transport effect and potentially is why some guidance is bringing that northern snowfall gradient more into the CWA. However, ample synoptic forcing for the afternoon and evening for snow -- heavy at times -- and then the lake enhanced support into far northeast Illinois for the evening and overnight, all continues to look in-line with the forecast. MTF

If we want to fuel the convection debate even more, LOT actually made mention of it in the evening update.

Gonna be another pound town run w/the lake contribution.

Here's a loop to illustrate this, showing pwats and low-mid level winds. Look at where the trajectories are from. >0.5" pwats on the wintry side of the system are pretty decent

I don't think the convection is a huge issue... at least not as much as some other times. As mentioned, we have the Pac moisture source. I get more concerned when there's a big east-west line of convection laying out and less of a Pac source.

If ORD gets a little over 8" with this storm, they would be sitting at the average snow to date as of Jan 2.

2022. Wow. Onto a better month than December was for most of us.

I think it may be too aggressive this time though. I'd like to see better delta T and inversion heights. So i'm not willing to go with 18" amounts near the lake. 12"+, ok.

I do remember the HRRR being overzealous with lake contribution in some previous setups. But even cutting it down would result in isolated 12"+ amounts near the lake.

Going warning in my head even if it doesn't happen officially They say you have to smell the rain to get the best snows. Looks like that may be the case with a rain/snow line not too far south. Other than some spits of drizzle/light rain early on, I expect almost all of it to be snow. One thing I am wondering is how long it will take from snow onset for temps to dip below freezing. The first few hours could be a little unproductive with accumulation.

I'm still liking 6+ here, fwiw

Here's a fun little list. Biggest holiday/sort-of-holiday snows in met/astronomical winter for Chicago: Christmas day: 5.1" - 1950 New Year's day: 5.0" - 1918 Valentine's day: 8.3" - 1990 St. Patrick's day: 4.1" - 1984