10/30-10/31 Wed-Thurs Halloween Snowstorm Update #4

We continue to inch closer to the start of this storm system and impending snowstorm across portions of the state as accumulating snow continues to look very likely for some. The system itself is still slowly organizing well to our west but its effects will be felt as early as late tonight and early tomorrow morning for some. I dig into the latest details below....along with expected snowfall amounts.

Our storm system continues to slowly come south and southeast this afternoon across Nevada and Utah and by later tonight it will begin to turn more east and eject out into the plains with its sights set on the Midwest. This is quite the impressive upper level low and what will end up being our snow maker. 

Precipitation is still expected to develop this evening off to our southwest and move into a good portion of the state by late tonight with mostly rain for awhile. As precipitation moves further north, it will encounter colder temperatures where a narrow of snow is looking likely across portions of northern Illinois tomorrow morning. As you can see in the loop below that runs from 3pm today till 7pm on Thursday, temperatures will warm during the heart of the afternoon on Wednesday, leading to mostly rain for all of Illinois outside of maybe far northwest Illinois. As the upper level low approaches from the west, cold air advection will commence from west to east into portions of the state coinciding with another area of widespread precipitation coming back into the area from the southwest. 

As mentioned above, surface temperatures will fall into the upper 20's to low 30's by Thursday morning and afternoon from west to east with the visualization below. As this occurs, expect rain to flip back to snow across portions of northern and central Illinois. 

So to recap, the first round of accumulating snow will come very early tomorrow morning into the late morning hours in a corridor from western Illinois on northeast into around the Chicago metro and some portions of northern Illinois but.....this will most likely be a narrow band of snow so not a lot of people with see sticking snow. Rain will then be the norm Wednesday afternoon and evening and potentially a break in there at some point. As precipitation moves back in Thursday morning, expect a changeover back to snow by mid-late morning Thursday and continuing into the early evening hours across much of northern Illinois. Below is our first TAM/expected snowfall totals for the entire event from early tomorrow morning through Thursday night. Expected continued updates over the next 24 hours.