Hoosier

LOT actually just issued a Winter Storm Watch for parts of Cook county.

Alrighty then. My favored jack zone is somewhere between Hyde Park and East Chicago. I think LOT is going to need some kind of winter wx headline for Cook county on the afternoon package.

Latest HRRR hammers Chicago. We discussing this here or in the January thread?

Yeah, although you look to be in a pretty good spot this time. I'm a little nervous with how quickly the band starts to hug the immediate shore on some guidance. Certainly have a bit higher confidence in sig amounts for you than me.

That Euro was the relatively rare progression of sig snow to ice to rain around here. Usually don't see the front end wintry precip last as long.

Well, 00z Euro bullseyes downtown Chicago with the lake effect. That is probably a lower probability scenario, but can't rule anything out. If I had to guess, the jackpot is likely to be south of downtown in Cook county or in Lake county IN. I feel that Porter county is a somewhat lower probability scenario to jackpot as residence time looks shorter there.

There's really only one guy there who could have such a verbose thread title. I don't even need to go there to check.

Nice disco from RC regarding lake effect potential. Not that they need my validation whatsoever, but there's not much for me to disagree with. The main concern is the likelihood of heavy accumulating lake effect snow and travel impacts Thursday night into Friday morning for portions of (especially) far northwest Indiana, but possibly including areas south of downtown Chicago to extreme eastern Illinois. Concern is there for snowfall rates of 1-2" per hour in a dominant band setup, though uncertainty on exactly where convergence axis will set up and residence time of the heavier snow keeps confidence low enough to refrain from winter storm watch issuance. A quiet and seasonably cold weekend will follow, with attention then turning toward a likely active stretch Tuesday-Wednesday and beyond. [Thursday Night into Friday Lake Effect Snow Threat] In the wake of Thursday afternoon`s cold front passage, another surge of modified Arctic air featuring 850 mb temps of about -17 to -19C will move down the still relatively mild ice free expanse of Lake Michigan. Ice behavior on far southern portion of the lake in response to the gusty southerly winds ahead of the front on Thursday is rather uncertain, but may not play a huge role in the lake effect snow forecast. Lake effect parameter (instability, convergence and lift, and inversion height) wise, the thinking is that conditions will be favorable for heavy rates maxing out at ~1-2"/hour. Forecast soundings indicate inversion heights up to 7kft or a bit higher with potential instability up in the 350-500 j/kg range. Main limiting factor noted is dry air and subsidence above the lake effect convective layer, though current thinking is this element won`t be overly prohibitive. The guidance is in good big picture agreement in depiction of strong land breeze convergence developing over the far southern portion of the lake. However, the mesoscale uncertainty pertains to exactly where the convergent band sets up initially, then how progressive this band is in pivoting to the west into early Friday. In addition, as boundary layer flow tails off late, potential for mesolow development also may throw a wrench into things, as heaviest snow could slip just offshore by or even prior to daybreak Friday. The threat zone for substantial winter impacts ranges from southeastern Cook County (including Chicago mainly south of downtown) eastward across northern Lake and Porter Counties. In the official forecast, we have highest totals of 4-6" over northern Lake and Porter Counties, though for the reasons listed above and as is typical with lake effect, confidence is low at this lead time. Late tomorrow night into early Friday, based off solid northerly fetch over the lake and instability forecast, there could be decent inland extent of light to moderate rates to near or south of the Kankakee River for a time. Timing of the expected lake effect snow with the usual addition of rapid changes over short distances making things more hazardous unfortunately gets into the Friday morning commute. If the concerning heavy rates do materialize but residence time in any given spot is short, we may be able to get by with an advisory. However, considering what occurred this past Sunday morning, ~3-5 hour residence time in this expected set-up could certainly lead to 6"+ totals over a short time and significant commute impacts to 80/94 corridor into perhaps south half of Chicago. We held off on Winter Storm Watch issuance for any counties, but will hit the threat harder in local graphical messaging.

I was asleep at the wheel since it's still January.

Liking what I'm seeing on the 12z runs. Healthy convergence pointed right into Lake county IN on Friday. The heart of the band shouldn't have trouble ripping at 1-2" per hour for a time. There is a signal for the band to start hugging the shore more with time and have less inland penetration, so we'll see.

The floor with the late week lake effect sort of feels like 3-5" to me. That would be with a somewhat less organized band or a band that keeps moves around. 6+ would be on the table somewhere imo if it were to stall out for a prolonged period. Keep in mind this is just an early guess/outline of scenarios. Op models are not particularly useful for determining lake effect amounts. The hi-res models sometimes aren't either, but I'd tend to lean a little more in that direction. The hi-res stuff isn't out far enough yet though, so my numbers are mainly based on feel. I don't work off of lake effect charts/decision trees. Sort of like the grandma who doesn't use a written recipe to cook lol

Reverse psychology?

From LOT afternoon afd .LONG TERM... Issued at 157 PM CST Tue Jan 25 2022 Thursday through Tuesday... The primary forecast concern during the extended period continues to focus on the threat of a potentially impactful lake effect snow event across the southwest shores of Lake Michigan Thursday night into Friday. The beginning of the forecast period (on Thursday) will be one of the mildest days (relatively speaking) until next week. Breezy southwesterly winds are expected on Thursday in advance of our next approaching cold front, and this will push a warmer airmass into our area during the day. Temperatures look to top out into the low 30s Thursday afternoon, but this will be a short lived warm-up as the cold front will quickly shift southward across the area into Thursday evening. While not as cold as the current arctic airmass, this next push of cold should drive temperatures back down into the teens Thursday night and Friday. The main concern with this next push of cold will be the threat for a potentially significant band of accumulating lake effect snow Thursday night into Friday. Naturally, forecasting lake effect snow 60+ hours out carries significant uncertainties, such as the character of the snow showers (e.g., single band, or multi banded showers), along with their actual favored placement. Another complicating, and potentially negating, factor that could play a role with this event is the potential negative influence of the building ice cover along the shores. While this period is currently beyond the time period covered by the HiRes guidance, signs in the global guidance continue to support a favorable setup for a convergent band of lake effect snow across southern Lake Michigan Thursday night into Friday. The magnitude and inland extent of the accumulating lake effect snow into far northeastern IL and northwestern IN remains unclear at this time. This will need to continue to be monitored.

My mom was at the Dunes this past weekend and said there was ice around the shore. Looking at satellite imagery, there is a ring of ice around the shore. It doesn't extend out very far though and our setup will feature a long fetch over open water, so the ice near the shore shouldn't be that much of a factor.

We'll see, but it looks like there's a window for downtown. Check out my LES post in the Jan thread.

The lake effect potential on the southern end of Lake Michigan later this week looks like it could be around an 18-24 hour thing, give or take. A number of parameters look fairly similar to the event from a few days ago (but longer this time) and I don't think it's a question of whether there will be an organized band. The bigger question is what is happening during those 18-24 hours -- does it meander around a lot or can it spend many of those hours in the same area? I think several inches would be achievable even with a reasonable amount of meandering, let alone if it stalls out somewhere for a long time. The ingredients are there (decent delta T and inversion heights, good low level convergence, healthy omega in the dgz, etc) for inch+ per hour type rates so you can get an idea of what could happen if it did manage to stall.

You want the GFS.

Cool

^In case anyone is wondering, 2020-21 had 25.4" at the end of January, so it did not make the criteria.

ORD is sitting at 12.5" of snow so far this winter. There likely won't be much more snow at the ob site for the rest of this month, so heading into February sub 15" looks like all but a lock. There have been 47 years in which Chicago had less than 15" going into February, so it's actually not that uncommon (about once every 3 years). Here's the bad news. Out of those 47 years, only 5 ended up being snowier than average by the time the last flake fell. They are: 1900-01: 40.9" 1925-26: 52.3" 1953-54: 43.2" 1971-72: 46.8" 1979-80: 42.4" The other 42 years ranged from very bad to a bit below average snow by the time it was all said and done. There's still plenty of time to rally, but it may be wise to keep expectations in check.

By any objective measure, this winter isn't a C at this point. Unless maybe your start date is January 1.

Looks like generally 5-7" fell in the county.

I usually don't mind. The heavier snows that are wet are not so fun though. Most of my neighbors have a blower but I would only ask to borrow it in an extreme circumstance, like if it's a foot of paste or something. Never used a blower last year during that insane February.

February should be good if you're around the Lakes or at similar latitude. It's more questionable farther south, but hopefully things can break favorably for those areas to have some fun.

Looks like there could be another shot of some lake effect somewhere around the southern tip of Lake Michigan around the end of the week.