RCNYILWX

There definitely looks to be a warm period next week as the western ridge finally slides east. After that, there's reasons to think the pattern could be workable for parts of the region next weekend and beyond. Key feature would be the continued west based -NAO and to a lesser extent the AO. Based on stratospheric discussion the past few days, there could be some flux in the polar domains which may affect predictability farther out. The EPO is currently modeled to trend strongly positive for a time, but then become less strongly positive. A positive EPO certainly points towards a generally warmer pattern. But the magnitude matters, and in February, a -NAO could do more work given the thick snow and ice cover over Canada vs earlier in the season. The way I see it, the risk is absolutely there for warmer systems, but the -PNA at least gives a chance for decent storms coming out of the southwest. Since it appears the NAO should remain generally negative, you can still get snow/ice threats even in an unfavorable EPO setting (assuming that holds as modeled). Seems like a pattern in which being farther west and north would tend to be more helpful with a fairly potent southeast ridge favored. I'd prefer to roll the dice with this than more endless cold northwest flow. Even if winter threats don't work out, I'm personally over the persistent cold weather we've had since mid January.

Chucking them deep [emoji894][emoji894]: Jan 24-25, 2000 redux, the real ones know. I think I was on Tristate weather forum or whatever it was called at the time. That was my sophomore year at Bronx Science. Still crazy to think that a storm that was supposed to be a whiff tracked so close to the coast that we changed to sleet in the city and then dryslotted. Sent from my SM-S936U using Tapatalk

Of course not following expectations once we tried to simplify the headlines - good ol' lake effect lol. The good news is that while the lakefront has been mostly whiffed since this morning, there's also lot of people in the nearby suburbs in Cook where it has been snowing hard. Curious to see how tomorrow plays out, with strong convergence but steadily decreasing inversion heights and delta Ts. Sent from my SM-S936U using Tapatalk

The 3km NAM has been too low with lake enhanced/lake effect QPF, so simulated reflectivity and modeled visibility, plus forecast soundings, have been much more useful lately. When a model is showing a half mile or less visibility in snow, it's resolving heavy snow, so the QPF/snow not matching up doesn't necessarily mean much in this particular setup. The HRRR looks very close for the city tomorrow evening too and if the band maintains enough intensity and does get back into IL on Saturday, it could still have nice rates with it. Another thing to keep in mind beyond the QPF is that ratios in the heaviest snow are basically a lock to be over 20:1 and quite possibly 30:1 or higher. So this is also a situation where the Kuchera ratios won't be high enough. The marine layer creates a bubble of slightly warmer temps that incorrectly lowers the ratios (method is based on layer MaxT from sfc to 500 mb).

On the other hand, gotta feel for people who booked ski vacations out west this winter. Yikes. Sent from my SM-S936U using Tapatalk

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