RCNYILWX

Re. the Central Park ob and possibility of officially getting to 20+, hopefully OKX has an agreement with the CPK Conservancy folks who do the measuring to take a measurement once the snow fully comes to a stop. The 6 hour board clearing rule doesn't apply when the accumulating snow ends. For FAA contract observer sites, if the arrangement is the same there as it is out here, we call them for the final measurement when confident there's no more accumulation on the way. Sent from my SM-S936U using Tapatalk

As a meteorologist, pet peeve is spelling lightning as lightening, which is most commonly associated with late in pregnancy ha. Keep up the great updates otherwise! Sent from my SM-S936U using Tapatalk

That's radar ground clutter. You can better tell it's an artifact by flipping over to velocity. https://www.noaa.gov/jetstream/anomalous-propagation Sent from my SM-S936U using Tapatalk

That's Z time, for Zulu time, which is the same thing as Greenwich Mean Time (GMT). It's the time system used in meteorology and in aviation. 00z in EST(EDT) is 7pm (8pm), 06z is 1am (2am), 12z is 7am (8am), and 18z is 1pm (2pm). Sent from my SM-S936U using Tapatalk

No prob! I work and live in the Chicago area (NWS met at WFO Chicago/LOT) but I grew up in Queens in NYC and started my career at OKX. Wish I could be there to experience this one but happy to offer insight to any questions about the storm. Sent from my SM-S936U using Tapatalk

Very high moisture content/QPF going into the snow doesn't necessarily yield very heavy wet snow. While the surface temps started off mild and above freezing, the rest of the profile isn't marginally cold. To get the really gloppy heavy wet snow you need surface temps near to even above 32, and a deep isothermal layer near freezing above it, which creates snowfall aggregates (clumps of snowflakes, almost like mini snowballs). This will be a dense snow and tough to shovel but still prone to blowing and drifting. The snow will get fluffier with time as colder air moves in and exacerbate the blowing and drifting into tomorrow morning, as that snow will be easily transported atop the denser snow below it. Edit: The very well written OKX AFD mentions initial 10:1 ratios (about climo for your area) improving to 12-14:1 with time, which seems reasonable. You'll probably have an effective ratio higher than 14:1 wherever the f-gen death band sets up. The heavy wet snow you may have been anticipating generally entails ratios as low as 5-8:1.

A few important aspects to keep in mind: - There is no human intervention in that dataset. The underlying NWS NDFD forecast is applied to the WPC super ensemble data and does adjust the statistical spectrum a bit, but this is done automatically. - There may be time lagging affecting the low end members of the super ensemble, with various inputs possibly being earlier model cycles. - The above being said, given the extreme top end of the spectrum which we can see with the GFS (and many GEFS members) and NAM, those top end 90th percentile amounts are physically plausible, and again, automatically derived (with a ratio applied I believe). - There is certainly a good deal less spread now than earlier today, but you'll still have some ensemble members that have much lower QPF at this range (and some of these may be from earlier cycles, as noted above). For this reason, the 10th percentile low end amount undeniably seems ridiculous given the extreme top end amounts, but in this case, the 10th percentile is not completely unreasonable. As spread decreases, that will most certainly come up on subsequent runs. Sent from my SM-S936U using Tapatalk

Such textbook synoptics. The NAM and GFS progs are extreme, upper echelon - but think of it this way, 75% of that sort of outcome is still a crusher. Def wish my work schedule lined up in a way that I could have flown out to experience it. January 96 was a seminal event on my path towards becoming a NWS met. Ironically enough, during 2006 I was up skiing at Whiteface where we just had cirrus up there. And then in 2016 I had already been in the Chicago area for 5.5 years. Did get to experience the Feb 2010 craziness after missing the early month 'snowmageddon' and happened to be back in NYC during Nemo in 2013. Here's to an all timer for the area.

There's no such thing as a blizzard watch. Just a winter storm watch indicating the potential for blizzard conditions within the watch. Sent from my SM-S936U using Tapatalk

Also the NBM is gonna be incorrect bc there's a lot of time lagging involved in that dataset. If you have a way to view the percentile MaxT data, the 10th or 25th will probably be more representative. Sent from my SM-S936U using Tapatalk

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