RCNYILWX

Well said. That's why we did it that way. We're definitely not confident eastern portion of Cook will get nailed tomorrow evening, but if it does it could snow 6-8" in 3-4 hours, so we wanted to play it safe with the watch, and hold onto the watch for Lake and Porter to account for the typical LES funny business. And agree morning accums will likely be more localized vs widespread. Parameter space looks legit for 1"+/hr rates in spots under the heaviest echoes. Sent from my SM-S936U using Tapatalk

Not overly optimistic for a shake up to a pattern more conducive to regional winter storms in this part of the subforum until out towards mid Feb. An improved clipper pattern may eventually evolve as the western ridge axis centers farther west up into AK late in the first week of February and reduces the amplitude of the +PNA. As of the most recent available ensemble forecast teleconnection indices, signal is there for PNA to trend to at least slightly negative by or after the Superbowl. Since there's been headfakes regarding pairing -PNA with favorable teleconnection indices for cold (-EPO and -AO/-NAO), it's much too far out yet to get too excited. The good news is that the pattern should remain persistently near to below normal temperature wise, so there should be some opportunities for a few bouts of light to moderate snowfalls (aside from LES potential) until pattern possibly becomes more conducive for a time by mid Feb. Wait and see approach. Edit: Wanted to incorporate a bit of MJO here, but the CPC page isn't working well today. If anyone has MJO insights, interested in those thoughts as well.

Nice signal on the 12z globals so far, particularly the UKMET, which did well with the weekend LE. Sent from my SM-S936U using Tapatalk

Who's starting the LES thread? Looking solid again for a noteworthy event in IL-IN-probably SW MI (may include SE WI as well depending on boundary layer convergence orientation). Sent from my SM-S936U using Tapatalk

Regardless of what the long range stuff shows, maybe the 2015 Superbowl rematch is a good omen... Sent from my SM-S936U using Tapatalk

My thinking was set it to prime time tomorrow, with the extra week of rest for the winner. They may have also opted to move it elsewhere today. Sent from my SM-S936U using Tapatalk

List of the best IL side lake effect/lake enhanced events of the 2000s (feel free to add any that I missed in replies): 1/22/2005: https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=PNSLOT&e=200501230335 2/13-14/2007: https://www.weather.gov/lot/2007Feb13 2/8-9/2010: https://www.weather.gov/lot/2010feb09 1/2-1/3/2014: https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=RTPLOT&e=201401031600 1/21-22/2014 (NW Lake IN was hit hardest with locally 20-24" around Griffith, IN): https://www.weather.gov/lot/2014jan22 2/4-5/2014: https://www.weather.gov/lot/201314_winterevents 2/25-26/2015 (snow map looks like it was lake enhancement): https://www.weather.gov/lot/2015feb26 11/20-21/2015 (Nov 21st portion into Chicago/nearby): https://www.weather.gov/lot/21Nov2015snowfall 3/12-15/2017: https://www.weather.gov/lot/14March2017_snow 2/17-18/2019: https://www.weather.gov/lot/17Feb2019_snowice 2/14-16/2021: https://www.weather.gov/lot/Feb14-16_HeavySnow 1/28/2022: https://www.weather.gov/lot/2022Jan28 11/9-10/2025: https://www.weather.gov/lot/2025_11_10_LakeEffectSnow 1/24-1/25/2026: Ongoing

Seattle's time to make up for the 2015 debacle. Sent from my SM-S936U using Tapatalk

Absolutely, ratios are always tough, one of the toughest aspects of snow forecasting. From pretty far out, the Cobb did best (if the model was properly resolving QPF haha). I recall extended range NAM runs for the city showing 20-30:1 ratios. The Cobb was presumably too high for the pixie dust though. I was looking on my phone so I didn't sample the values on it, but it appeared Kuchera was outputting *lower* ratios in the lake enhancement zone, which is obviously incorrect in a setup like this. The Kuchera is based on the MaxT aloft from the surface to 500 mb, so onshore flow from the warmer lake is going to result in a warmer MaxT and hence lower ratios in the footprint of marine influence resolved by the model, vs the colder temps outside the marine layer.

Of the mesos, yeah I'd say. Of the globals, the non-GFS stuff did pretty much fine in the general idea (the AIGFS was head and shoulders better than the op GFS). The UKMET might have done the best overall bc it consistently showed 0.3"+ QPF right into Chicago. I think the NAM did pretty well with this event too all things considered. Sent from my SM-S936U using Tapatalk

If that has staying power, might need to upgrade some more counties to a WSW. I'm not at work so I can't speak to it but I do wonder if it's being considered. Would think your area, south burbs to especially northwest Indiana is prime bc they're going to be under lake enhancement and then pure lake effect for a while longer. Can see the LE under the synoptic snow into Lake County Indiana from tMDW. Sent from my SM-S936U using Tapatalk

Big dendrites here in Naperville (DuPage-Will border just north of Bolingbrook) too, noticeable uptick in flake size within past few minutes. Sent from my SM-S936U using Tapatalk

Looks like we're getting another surge of large scale forcing to hook up with the lake enhancement. Banding filling back in from the southwest. We'll see if the LES multi bands intensify even a bit more as this occurs. Sent from my SM-S936U using Tapatalk

The 00z HRRR and NAMnest initialized adequately with it. Suspiciously low QPF response given the evolution progged, although presumably it would be higher ratio than Kuchera output. Sent from my SM-S936U using Tapatalk

More recent radar frames suggest flake size may be soon or already is improving some up to roughly I-88 in the metro. Sent from my SM-S936U using Tapatalk

Oh just for full disclosure since I'm all about owning up to bad forecasts, my forecast earlier this week sucked (overnight snow the day before the evening squalls and snow bands that did work out). That was a different setup, but the dry air winning out there made me a little gunshy to feel confident the light snow would start much earlier. I did have a hunch something like this might play out, but in the 00z and 06z TAFs last night, didn't have flurries until 4pm at DPA and 5pm at ORD, MDW, GYY. Still leaned earlier than explicit guidance though based on how the soundings looked, and had a prob30 (30% prob) group starting with the flurries onset before the 1-2SM stuff in the evening. Someone should also tell many previous runs of the GFS that it is indeed snowing across much of northern IL today. Sent from my SM-S936U using Tapatalk

I tend to like 10:1 as a better first guess (in scenarios that aren't obviously well below climo ratios) and then consider the Kuchera if the Cobb output shows that the depicted Kuchera ratios are realistic. Case by case basis. Where the forcing is consistently good and well aligned with the DGZ for this event, it's a good air mass, so the Kuchera may be fairly reliable for this storm. I think up here (WSW Chicago burbs) it's gonna be mixed in terms of ratios. Looks like our better chance at solid ratios away from the lake might be tomorrow morning. Our morning AFD update mentioned that the snow at onset later today/this evening will more likely be pixies, aka Arctic dust.

This, not a fan of the brutal cold but prefer it to come with the ground covered than with bare ground. Sent from my SM-S936U using Tapatalk

How big was Feb 14-16, 2021 there? Sent from my SM-S936U using Tapatalk

Another CIPS analog here that did tick a bit northwest by go time, fairly close in to the event: https://www.weather.gov/lot/2014feb05 Sent from my SM-S936U using Tapatalk

Some of the recent CIPS analogs have included mid February 2021 and 2007. Sure, we could see suppression. As I'm sure most in here remember though, mid Feb 2021 at this lead time was pretty much a whiff for most of the Chicago metro. These juiced expansive Gulf lows seem to have a knack for trending north (maybe due to enhanced downstream ridging due to tremendous latent heat release?). So the fact that much of the guidance is already bringing accums to the Chicago metro area perhaps should give some reason for optimism here. Another big wildcard is the SLRs, which could be exceptionally high if lift is well aligned with the already modeled to be very deep DGZ in the very cold airmass. So even Kuchera ratios would potentially be too low. For reference, MDW 3SW had 0.51" of liquid equivalent in 15.7" of snow in 24 hours from 2/15 into 2/16/2021. So if we see consistency in relatively high QPF getting relatively far north, that would likely imply stronger ascent to generate the higher QPF, which itself would likely support unusually high SLRs. For this element, recommend checking out the Cobb text snowfall output via IEM or PSU (the 18z NAM Bufkit Cobb output showed 30:1 ratios at KMDW). Finally, the lake enhancement potential could be a noteworthy component of this, as occurred in the 2021 event (see MDW 3SW snow ob above), and back in 2007.

I know you know this, but using that wording inept idiots... I understood the grounds for criticism and questioning how it was done and like I said, we could have done one and probably ideally would have farther north. If I were some rando that just moved here for work and started posting, wouldn't be too excited about posting in the future after seeing that. I obviously know it comes with the territory here, us getting criticized at times. Sent from my SM-S936U using Tapatalk

For those who prefer not to bash given the challenges of these, there was a debate in the office when I was about to leave re. SQW. It's not as simple as just pushing a button. There's a specific criteria for visibility of less than one quarter mile that wasn't really being met at the ob sites as the squall moved through areas farther north. For that reason, there was active discussion including Gino Izzi (lead forecaster), our WCM, and the other lead that had just arrived on the best way to handle things. I personally weighed in on the side of issuing a SQW for downstream areas right before I left. From a lead time perspective, I'm happy I put out a SPS at 4:50am when it wasn't exactly clear how it would go and a graphic heads up. We also made a social media post last njght that gave a heads up. I thought something like this might be possible, if you read back to AFDs from past few early mornings, but this definitely overperformed and has been a top tier squall for this area. Ultimately, yes, we could have issued a SQW earlier that included the rest of the metro, but I think we gave a heads up about adverse conditions and got some lead time with the SQW for the south burbs and points south and east. For very tough forecasts, you win aspects of it, lose some, and learn and apply it to future similar scenarios. Thankfully the roads weren't too bad for most of my drive back home - only starting getting worse traction once almost into Naperville from north Bolingbrook. Edit: I guess the app really didn't like me trying to type out less than one quarter mile visibility with a less than symbol and numbers lol

Don't change bro Sent from my SM-S936U using Tapatalk

It's legit out there underneath the narrow heavier band. On my drive home from my crazy shift dealing with 2 seasons, conditions got worse going from Bolingbrook into Naperville. Even prior to that, with the strong cross winds, especially on intersections with Weber Road, conditions were sub optimal due to blowing snow. Actually getting dendrites here under the band despite the strong winds, and a solid coating down. I'm glad I put part of the CWA in a WWA but wish I went farther south with it. Hopefully a lot less people need to drive to their offices tomorrow with it still being the holidays. Sent from my SM-S936U using Tapatalk