ILSNOW

Great read from Izzi The forecast shear profiles are very concerning Wed afternoon and evening with 40-50kt of south-southwesterly flow at 925 mb veering to southwesterly at over 100kt at 500mb. This results in very long and exceptionally favorable hodographs for supercells. Very large, cyclonically curved hodographs in the 0-1km layer with mostly streamwise vorticity also would favor the potential for tornadoes, especially given the low LCLs. While the shear profiles are extreme, there remains considerable uncertainty. First, does the forecast magnitude of instability actually materialize as modeled tomorrow afternoon. Second, convergence looks rather weak along the front and it is unclear if it will be enough for convective initiation, assuming sufficient instability. Finally, guidance generally has our CWA in the convergent, right exit region of the strong upper level jet. Ultimately, there are many potential scenarios where we end up with only weak, non-severe convection in the late afternoon/early evening or no convection at all. Unfortunately, given sufficient instability and intense convection develops, the potential would exist for fast moving tornadic supercells, with the potential for strong tornadoes.

From storm prediction center The northern portion of this convection will be oriented more orthogonal to the ejecting mid-level jet, and current expectations are for quick upscale growth into a fast northeastward-moving band, posing a risk for widespread severe/damaging winds as this activity moves into IA and towards the MO/IA/IL border region. Given the strength of the low/mid-level flow and presence of steep lapse rates aloft, along with a well-mixed boundary layer, intense thunderstorm straight-line gusts peaking locally in the 80-100 mph range are possible with the stronger cores/inflections in the band as it matures and moves across parts of the mid MS Valley, and eventually into the southwestern Great Lakes this evening through tonight.

Got 0.0 yesterday although I saw about 10 flakes around 9:30 am

Chicago NWS While the strength of this system is expected to begin a weakening trend as it encounters more confluent mid-level flow across the western Great Lakes on Friday, there is concern that the snow could still fall at moderate to heavy rates at times (up to an inch per hour) during the day. This occurs as a band rather potent 850 to 700 mb frontogenesis looks to set up right across northern IL during the late morning and afternoon. Model cross sections across this tightening baroclinic zone depict a rather classic frontogenetical response, with forced ascent right into a layer characterized by negative Theta-E lapse rates (convectively unstable) through the DGZ. This suggests that some narrow heaver bands of snow will certainly be possible, with the most favored location for this being areas from I-80 northward late in the morning through the afternoon. Surface temperatures are expected to remain near freezing across far northern IL during the snowfall into Friday afternoon. Accordingly, this raises questions as to the extent of road snow accumulations and hence if any real travel impacts other than reduced visibilities will materialize. Current thinking is that most areas will only see some slushy accumulations on area roads, but in an areas that happen to fall under one of the more intense narrow bands, the snow may fall at a high enough rate to result in some snow covered roads and possible travel impacts. Unfortunately, however, the exact locations in which these narrow intense snow bands setup are very difficult to pinpoint with any degree of skill this far out. At this time, the most favored area for these bands of heavy snow resides north of I-80 in northern IL. The precipitation will come to an end by early Friday evening. Total snow accumulations of 2 to 3 inches (locally higher) look favorable north of I-80. Farther south, (south of I-80) warmer temperatures will limit accumulations, and may even result in any lingering precipitation falling as rain in the afternoon.

Can you please translate for us weather dummies!!!

I would say GFS at 240 plus hrs prolly has hit ratio of 0.0001

the 0.4 over Chicago will!!!!

earlier this week the "pattern" had changed to a more active one and we were looking at 3 possible snowstorms (Thursday, this weekend and mid week) and even pro mets were talking about the high possibility of 10+ inches here in Chicago from the first 2 storms, we all know it didnt happen for a variety of reasons and the upcoming 3rd snow storm will hit our friends in Kansas and Missouri (again). Have you noticed that we NEVER get a good bust in our area (there is no way the mid week KS/MO storm moves north because of a 1050 high pressure). So basically our 7 days of winter (snow) are done and now we can look forward to dry weather and below zero wind chills at night till it warms up and rains in early March.

yes this big "active" pattern change was not much (4-5 inches on ground from Wednesday and last night) this weekend is a miss east and midweek is a miss south.

In the category of it will never happen the 12Z UKMET tries to get ALEK close to his seasonal norms. Enjoy

Solid 2 inches here and done prolly have 5 inches from the 2” storms” actually looks like winter. Suxs that we got teased for 1 model run yesterday that we actually had a chance at a snowstorm, hope you guys to the east get hammered.

Roger, Chicago 7-8 inches????

Good luck Detroit

GEFS mean precip

ICON east

18z Euro

18z Euro

ICON t RGEM is an unbeatable combo just like the EURO and ETA were back in the day. lock it in!!!!!!!

It’s pretty clear to me that the 18z RGEM is the only model that has a grasp on the Friday/Saturday storm!/s

Snow has started here in Buffalo Grove.

ouch and Milwaukee just went WSW for Racine: WINTER STORM WARNING IN EFFECT FROM NOON WEDNESDAY TO 3 AM CST THURSDAY... * WHAT...Heavy snow expected. Total snow accumulations between 6 and 9 inches. Lake effect snow may bring locally higher totals.

12z Euro bring the Saturday storm back into the picture.

snippet from Milw Initially, dry Arctic air lingering at the surface will prevent snowfall from reaching the ground. However, by mid-morning Wednesday, expect boundary layer to saturate and steady snowfall to begin. Rates in the initial band will likely be in the 0.25-0.50 inch per hour range as it will primarily be driven by WAA in the 700-500 mb layer. That being said, high ratio snowfall is possible as the WAA actually nudges more of the column into the dendritic growth zone. The highest rates develop during the afternoon as low pressure begins to lift northward, WAA in the mid-levels is enhanced, and convergence off Lake Michigan begins to shift inland with a higher fetch. Rates up to 1 inch per hour are possible during this time frame, especially in the Milwaukee to Kenosha corridor