RCNYILWX

I think it's a bit of a wait and see until we have an even better idea on exact surface low track and can see signs of where things are pointing toward regarding position and magnitude of warm nose aloft. Sent from my SM-G965U using Tapatalk

Re. mixing issues near the lake, even though the lake is very mild for late Jan, I think it's probably still cold enough to preclude something like what happened in the November 2015 and 2018 events. If anything, assuming mixing line stays south, could see ratios being held lower along lake and just inland earlier on in the event due to the strong northeast flow. All the above said, if a 18z GFS and ECMWF (operational and ensemble) type solution verifies, or north of that, mixing south of I-80 is a lock and possibly up to or a bit north of I-80 for a time on Monday before cold air comes in on the backside. I do think the block will be our friend in helping avoid a much farther north mixing line. Sent from my SM-G965U using Tapatalk

Getting close to 100% for a top news story barring a horrible crapping the bed of this setup, since we do event pages even for light to moderate events. Chances for a historic event we'll be talking about years from now and be updating for anniversaries, let's say 10% right now. I don't want to rule it out, because at this lead time from GHD II, I can't recall anyone thinking historic amounts were in the offing, and we'll certainly have the moisture in place if it all works out right. For us starving Chicagoland snow enthusiasts, even getting it to perform to something like the EPS and GEFS ensemble means will be a feat in and of itself and I think it will be a fondly remembered event even if it's not historic. Edit: And speaking of the GHD I page, we're hoping to be able to update it to our current tabbed interface and add some new images such as a recreation of the snow amounts using our current graphics generation software for the 10 year anniversary. If anyone has suggestions for additions to that page, let me know in a PM or in the new past snowstorms thread.

Good evening y'all, just got back from the office a bit ago. Fun shift. Would be happy to answer any LOT specific questions if anyone has any. Regarding who's working in the lead up, I'll be back on evenings with Ratzer tomorrow through Monday and I expect I'll probably be doing evening update AFDs. Our midnight crew is the same as last night (Carlaw and Kluber) and it'll be them through the event. Dayshifts will be MTF and Petr. We should be in good hands. Glad that we stayed the course with the most consistent guidance in terms of our forecast lean and messaging in light of guidance trends already for 18z cycle. Here's to a good 00z cycle. Sent from my SM-G965U using Tapatalk

Everyone freaking out can put down the paper bags. Sent from my SM-G965U using Tapatalk

Without access to ensemble data from the UK, we don't know where the operational falls within the spread of its own ensemble system. The only more consistent forecast system has been the ECMWF/EPS. That said, while GFS operational has been very inconsistent, the overall suite has trended north the past several cycles, especially on the 12z GEFS. The UKMET is concerning in that it's a possible scenario that can't yet be ruled out. The 12z ECMWF/EPS are the big key to this. If there aren't big changes from the 06z, I'd consider the UK a lower probability southern outlier like the NAM. Edit: And I'd like to restate from yesterday, given antecedent pattern for this event, including initially pretty marginal thermals, I feel confident in saying we wouldnt even be in the game in most of northern IL without the NAO block. Maybe a more east based block could modulate enough and still keep us in the snow threat zone, but with a positive NAO, I don't see how Alek wouldn't be posting the Eurythmics video.

Absolutely. Pattern recognition and textbook meteorology >> raw model output in this case Sent from my SM-G965U using Tapatalk

Total toss on the verbatim depiction of the heavy qpf/snow swath on the GFS. That's a great surface and 700 mb low track for the metro. Sent from my SM-G965U using Tapatalk

Yep, if anyone has been following the under the hood analysis, the northern burbs are definitely not out of the game. Key thing to watch on the globals today is the track of the 700 mb low. Often times when mesoscale banding sets up, there can be one pretty well displaced to the northwest of the h7 low track.@weathafella can attest to this "mid-level magic" from east coast systems. Sent from my SM-G965U using Tapatalk

There's the suicidebooth.gif run from the NAM. Knowing how it struggles when the key features are mostly outside its domain space, definitely too early to put stock into it. Sent from my SM-G965U using Tapatalk

Really nice 700 mb low track on the UKMET for much of the Chicago metro to get in on the 700 mb deformation axis snows. Sent from my SM-G965U using Tapatalk

Agree, it's generally a mess. 700 mb streamlines and RH would indicate respectable banding up into WI and it crushes precip shield to mainly I-80 and south. This is where the human input into the forecast remains important, to be able to pick out these biases/flaws in the models and look deeper into the meteorology with respect to other mass fields that aren't as fickle as QPF, which seems to especially be the case with the GFS. Unfortunate part for this event too is that the GFS v16 hasn't been running since last night or something. Sent from my SM-G965U using Tapatalk

This run of the UK was several hours slower. Similar latitude at 18z Monday, but while 12z run was north of EVV at that time, the 00z run is just southwest of STL. There's been a decided slowing trend on the 00z guidance thus far. Sent from my SM-G965U using Tapatalk

Big time jump in the mean. Individual member low locations show clustering is most focused on the northern and northwest portion of the mean. Sent from my SM-G965U using Tapatalk

Took a little closer look at some of the soundings on the GFS and as we figured, it's pretty bogus. More than enough lower and mid-level saturation gets up into southern WI on that run, and considering placement and magnitude of large scale forcing, if I didn't have access to QPF, I would have the northern extent of the QPF shield probably up close to MKE. Sent from my SM-G965U using Tapatalk

Need a little dose of old school meteorology on that run of the GFS. Regardless of the confluence to the northeast, the surface and h7 low track depicted would not have nearly as compact a cold sector precip shield imo. It's a close to ideal 700 mb low track and surface low track shown to get heavy snow up into the Chicago metro. Sent from my SM-G965U using Tapatalk

Appreciate your contributions on here while you're out in the area! Always enjoy your posts and those of other knowledgeable posters when lurking on the NE threads.@OceanStWx should pay us a visit on this thread if it's not too busy over there haha. Sent from my SM-G965U using Tapatalk

Oh I didn't think you were, I wanted to provide some clarification since I had done the forecast and made the graphic. I appreciate the feedback and having been a part of our social media and graphics team for a while, we do try to incorporate feedback into improvements and how we convey things. Sent from my SM-G965U using Tapatalk

I made the graphic and wasnt trying to convey overly high confidence in those amounts. It's pretty reasonable to say at this juncture that if the ingredients all come together, that a swath of 6" of snow is fairly likely given the forcing and moisture available. I was hoping to make note of the uncertainty by italicizing and underlining possible wording. The shaded areas used are pretty much WPC's Day 5 outlook (dark blue is the darker green 30-50% area and lighter blue is the lighter green 10-30% area). Of course we can see in the spectrum of outcomes, there's still a lower probability completely failure mode in this. We decided that if we're going to ramp up messaging for an event a little farther out, may as well be this one. * If* subsequent trends do support the higher end outcome, we're probably 3 full forecast package issuances away from watch issuance (Friday night/Sat AM midnight shift). Sent from my SM-G965U using Tapatalk

Yup, looked like should be partial for 12z and should be full sampling for 00z tomorrow. The PV lobe southwest of the block that's also a key player is up over NW Territories. Sent from my SM-G965U using Tapatalk

Been thinking the same thing, feel pretty confident that sans blocking this would be a much warmer outcome. The blocking could yield a failure mode, but the heights ahead of the wave are already pretty amped, with no block, they really pump and SLP track is probably over the LOT CWA. Sent from my SM-G965U using Tapatalk

I'm not seeing stronger with northern stream, if we're referring to the PV lobe over Manitoba. Unless I'm looking at it wrong it looks like it's a hair west northwest of 12z and there's subtle higher heights than 12z over eastern Ontario. To me biggest change is the shortwave is a little slower and more positively tilted. Could get to that farther south outcome anyway but I'm not sure it's due to the northern stream. Sent from my SM-G965U using Tapatalk

LOT long-term AFD out, nice and short as usual from me Sent from my SM-G965U using Tapatalk

12z EPS now centered from QCA to Chicago metro roughly. Lots of good hits on the members, would like to get rid of the remaining duds. I'm busy getting the forecast out so don't have time to post images today. Sent from my SM-G965U using Tapatalk

What's nice about this setup is that we're not relying on an exotic phase, like some of the fails the past few winters. Main sensitivity is to the magnitude of confluence from the NAO blocking and to a lesser extent the magnitude of the main shortwave itself. We're seeing the potential here if that confluence can stay far enough north. Still some failure modes, but also plenty of reasons why this has legs. Another important thing to keep in mind is that without that block, there's no event here, background pattern of plunging -PNA (which would normally yield a strongly amplifying SE ridge), La Nina forcing, and point of entry of the southern stream wave probably would be a pretty warm cutter. So there's some concern lingering for suppression, but lessening vs yesterday given trends since then. I think concern for wave coming in too far north and bringing mixing issues farther north is a valid one too. All in all, I like where we sit and we have some wiggle room.