ILSNOW

our buddy with and update National Weather Service Chicago/Romeoville, IL 1032 AM CST Mon Dec 28 2020 .UPDATE... 1032 AM CST No big changes to the forecast for tomorrow-tomorrow night`s wintry precip event. In addition to a decision on the Winter Storm Watch for Winnebago, Boone, and Ogle Counties, will be needing a Winter Weather Advisory for a good chunk of the remainder of the CWA, likely including the entire Chicago metro. Will defer these decisions to the full afternoon forecast package issuance. Looking at the 12z suite thus far, noting a tendency for pretty rapid top-down saturation of the initially dry cP air mass in the wake of departing high pressure, so envision a bit earlier onset than in current official forecast. Ingredients discussed in the short term discussion from the overnight shift are certainly there, with their longest duration and impacts generally where the watch is in effect. Forecast soundings indicate that the snow will likely fall at a moderate to even heavy clip along and north of the Kankakee River (shorter duration south of I-80), with strong omega well aligned with the DGZ into the early to mid evening. Onset time of the snow will be just prior to and during the afternoon commute hours, so travel impacts are likely. With the strong LLJ driving strong WAA, eventually a warm nose will surge in aloft during the mid to late evening, changing precip over to sleet and then freezing rain, latest in the far north where snow should hold on a bit longer. Given the accumulating snow, followed by sleet and then up to to 1/10-2/10" ice, hazardous travel can be expected, warranting expected advisory issuance and perhaps upgrade to warning where a watch is in effect. Castro

GEM wave 1

Long way off and lots can and will change But talk about a dramatic cutoff!!!!

A little icy

Ride the ICON

This says it all 240 hr maps are meaningless but LOL at the Chicago donut whole.

Enjoy

You want to remember what tracking a potential winter storm is like head over to the nyc forum where they are tracking a potential 15-30 inch storm. Very jealous hoping for a few mood flakes later.

snippet from Chicago NWS The primary forecast challenges in the extended period continue to focus on the evolution of a storm system that is likely to impact the area late Friday through Saturday night. This storm system promises to bring a significant amount of precipitation to the area, but mainly with most of it falling as rain over central and eastern IL into northwestern IN. However, the potential exists for significant snow accumulations for at least parts of far northwestern into far north central IL and points northward into WI. Therefore, we could see a very sharp gradient between significant snow, and little to no snow somewhere right across northern IL, possible even nearing parts of the western/ northwestern suburbs of Chicago. Model and ensemble guidance is in decent agreement with surface low pressure taking shape over the southern Plains on Friday in response to the approach of the upper level low currently off the Baja of California coast. The exact track of the surface low is always key to determine where the accumulating snow will fall. Current indications continue to support a northeast track of the low from near STL early Saturday morning, to northwestern IN early Saturday afternoon. This track, would favor the main area of accumulating snowfall to be roughly across my northwestern areas, namely the Rockford metro area and possibly as far southeast as parts of the far northwestern Chicago suburbs. Mainly a rain event looks to be in store for much of the rest of the region. We will have to continue to watch this closely as even a minor shift in the expected track could change this scenario, so stay tuned!

10:1 snow map clearly overdone (prolly cut it in half)

12Z GFS Nice storm for northwestern IL and SE Wisc

this is correct map. Thanks Hoosier

Alek to your point.

IL just announced that there were systems issues with calculating the # of deaths during the past 24 hours and that todays # will be adjusted upward tomorrow.

12,702 new cases in IL with 43 additional deaths. A new record for the 3rd consecutive day.

10,573 new cases in IL with 14 new deaths.

10,376 new cases in IL with 49 deaths

9,935 new cases in IL today

3 here nice surprise

latest from LOT

Corrected

GFS says Alek busts high

NAM settling back south toward other models