RCNYILWX

Figure the amount of convection in the warm sector is something that may also contribute to struggles in handling the evolution of this system. Sent from my SM-G998U using Tapatalk

Yep, based off that, no real changes in thinking. It's good to see the ensemble not hugging the operational with plenty of members still supporting a good outcome here as you noted. The obvious caveat is there's members also similar to the operational, so that solution remains plausible, though the majority are west of the operational. The mean was actually a tick west and stronger from the 06z run. Sent from my SM-G998U using Tapatalk

2022 had good snows too in Kankakee County. Sent from my SM-G998U using Tapatalk

Will be interesting to see the 12z GEFS, starting to roll out now. The 06z operational was similar to the 12z, but the 06z GEFS still had a majority of members northwest of the op. We're still at the phase of the forecast where these operational solutions fit within the ensemble spectrum. The snow enthusiast in me would be lying if I said seeing sharp cutoffs like that in the modeling don't make me nervous (shades of 2/24/16, also in a strong Niño) but in this case there really is plenty of time left.

The weathernerds site has sounding data out to 240 hours for the 00z and 12z ECMWF runs. Here's an example from a random point I picked in New England at hour 90 of the 06z run. It looks like a bit better resolution than on WxBell and there's also a data readout from any pressure level you pick on the sounding. https://www.weathernerds.org/models/ecfull.html?&inittype=zoom&initfield=Get_Skewt&initcycle=determine&initfhour=090&initimdimx=1050&initimdimy=630&initrange=55.000000000000:230.000000000000:20.000000000000:300.000000000000&initcx1=0&initcy1=0&initcx2=0&initcy2=0&initcross=False&initsound=True&initsoundx=847&initsoundy=196&initloop=False&initoverlay=False&initlstart=000&initlend=240&initlint=3&initol1=Get_Skewt&initol2=null&initol3=null&initol4=null&initol5=null&initcities=On&inithgwys=On&initunits=On&initlatlon=Off Sent from my SM-G998U using Tapatalk

If you treat the operational runs as essentially ensemble members in their own right, especially at this range of the forecast, it makes sense to see blips like the 12z Euro operational, since there had already been ensemble solutions similar to that. A wide range of outcomes remain on the table while the big picture idea of a strong/deepening SLP tracking over the region still holds. Assuming the Pacific recon flights are happening, that may help narrow the goalposts some by later in the work week. Sent from my SM-G998U using Tapatalk

A paste bomb with wind could be very high impact if the SLP comes in anywhere close to as deep as recent Euro and GFS op runs and many ensemble members. The system doesn't look all that progressive to me as modeled relative to other past higher end synoptic systems. Your point about lack of cold air is certainly valid though. With the south buoy still 43 degrees, and unlikely to cool off more than a couple degrees over the next week, could make for white rain on the lakeshore and a few to several miles inland until winds turn offshore. Think the November 25-26, 2018 snowstorm.

You're not wrong that in the GFS depiction, it would start out mild due to the easterly fetch off the mild ocean. Except the flow does turn northeasterly enough to cool things off. It doesn't have to go due north to funnel colder and drier air southward. Look at the lower dew points to the north of NYC/LI during the day. Once the surface low tracks far enough east, the subtle shift to more NE from E and ENE to start the day plus the air mass being cold enough aloft and higher precip rates amidst lower dew point air being advected southwest helps cool the boundary layer via dynamical and evaporative cooling. It might take longer in reality than the model shows to cool off because of how warm the marine layer is over the well above normal SSTs, but the process the 06z GFS shows is still physically valid with the track it depicts. Sent from my SM-G998U using Tapatalk

The signal for a powerful storm is something else at this lead time. We received word that there will be Pacific recon flights this winter to help with upper air data for the models. Hopefully that helps make for a better forecast farther out. Sent from my SM-G998U using Tapatalk

For much of the LOT CWA, one of the more impressive EPS 10:1 snow means for our area in the day 8-15, with the 48 hour at about 5" valid ending Wednesday evening Jan 13th and about 6-8" across the Chicago metro for the 7 day period ending 00z 1/15. Given the look at the end of both the EPS and GEFS, as discussed in the AFD, regardless of how the potential big storm plays out early in the week, barring major changes, we will have additional opportunities, perhaps several, and a good chunk of the sub-forum could get in on the fun. The nice thing to see was the trend toward more of a -EPO with the continued -NAO/-AO that would keep a steady supply of cold air from our source region along with helping keep eastern mid-level heights in check amidst the continued active -PNA pattern.

With a downstream -NAO, could see some modulation of the shortwave trajectory. Alternatively, even if the potential/probable system in the 9th-10th timeframe ends up a more wound up cutter, that could serve to shunt the baroclinic zone farther southeast. Since western troughing will persist with the -PNA, we should see follow-up waves ejecting out and then the -NAO could stand to benefit us. Both the EPS and GEFS last night were strongly hinting at an active 2nd week of January, so there should be few chances to get something decent.

It's not a Snow Squall Emergency, it's a Snow Squall Warning (SQW) with a 'significant' tag selected that will trigger the WEAs. Baseline SQWs will no longer get WEAs. I'm not sure how other offices are handling it but we're in disagreement with the policy and will not be issuing non WEA SQWs. We will only issue 'significant' SQWs that activate WEAs (between 5am and 10pm on weekdays and 7am and 10pm on weekends). https://www.weather.gov/media/safety/Snow-Squall-IBW.pdf&ved=2ahUKEwjb3LmU4bODAxXcAHkGHTtqBzQQFnoECBsQAQ&usg=AOvVaw0Cpc_VkwVJaiOH4JJHj9VZ

Understand the tendency to feel jaded by recent winters. We had a rough winter out here last year too. The 12z GEFS looks pretty similar to the EPS. From about 1/8-1/11 would be the concern for a more wrapped up cutter given the progged AN heights in that period. And on the GEFS, it verbatim gets the 850 0 line farther north. On the other hand, with the NAO forecast to be solidly negative, also seems like a setup (should it come to fruition) that could be conducive to a SWFE. Then beyond that window, the pattern looks generally favorable with H5 heights trending to a bit below normal and a nice upper jet max focused over the southeast.

Long time lurker (and very occasional poster) in this sub. I know the ensembles don't equal the reality of what snow lovers want, but isn't the pattern offered by the 12z EPS for week 2 typically a decent one for New England, objectively speaking? Neutralish EPO with a -PNA, -AO, -NAO, no semblance of well AN h5 heights nearby and 850 mb temp anomalies near to slightly above normal with the 850 mb 0C line in the vicinity of the Delmarva. It's not a cold pattern, but the -PNA would provide a steady stream of shortwaves and the -NAO/-AO could modulate the storm track in a beneficial way and/or promote coastal re-development of primary shortwaves tracking inland. Wasn't necessarily expecting that sort of look to be in play for this winter, but from my perspective (NWS Chicago forecaster), that projected pattern is typically a productive one here and have also been associated with snowy patterns into New England. Thinking 2010-11, temporarily in early Feb 2015, and mid-late January into February 2021 and 2022 as some noteworthy examples. I'd go as far as saying that the projected EPS pattern doesn't look like a bad one even down into the NYC area (I'm originally from Queens).

Fantastic read - do you post this on a vLab forum in the NWS? If not, you should! We could all learn from analysis like this. I certainly am versed in some of the teleconnection stuff but not nearly to this level, and then you bring it together on the planetary wave scale, which is impressive. We haven't been optimistic locally about snow prospects this winter based off the moderate to strong Niño climo, but felt that the wild card for a time could be temps. Of the 10 mod-strong episodes, 4 or 5 had near to below normal temps, but of those, only 2009-10 had above normal snow. Since this month has been such a torch though, going to be tough to finish at or below normal for DJF temps. I'm intrigued by the temporary -PNA that looks to occur toward mid month before potentially more pronounced pattern change. If there's enough blocking, the storm track could be modulated to support a colder/snowier outcome. We tend to do pretty well out here with a -PNA/-NAO/-AO, a recent example being late January-mid to late February 2021. Interestingly, the 2015-16 super Niño narrowly missed out on above normal snow at ORD with the Feb 24th event *just* missing to the southeast. It certainly helped to have a big late November snowstorm, but I'd say that after the December torch, that winter was relatively wintry vs. expectations going in.

In a brief change from the mild and quiet nothingness that's typified this month, a PV lobe will bring a respectable (by December 2023 standards) shot of cold air and wind for Monday-Monday night. The Euro and EPS suggest a decent LES response with inversion heights climbing to around 700 mb, so could see some accums into the Indiana and Michigan lake effect belts. While the temps won't be anything to write home about, the wind and seasonable cold combo will certainly feel unpleasant coming off the mild stretch we've had. Sent from my SM-G998U using Tapatalk

We've grown accustomed to quiet patterns in December recently, but I think this stretch we're entering may take the cake. If the end of the ensembles are to be believed, it'll take until at least the end of the month to see some retraction of the higher end Pacific jet extension that will flood much of North America with mild air over the next couple weeks. Even then, if the pattern does eventually transition to colder in January, if it's driven by a +PNA, that would favor extending the drier than normal pattern. Sent from my SM-G998U using Tapatalk

Still too early to lock in a certain scenario, but the 12z guidance consensus suggests less of a snow threat for the LOT CWA and a severe threat potentially extending into a portion of the CWA on Saturday PM.

Also, not putting much stock in these runs for a few more days, but that run brings up nightmares of 2/24/2016 lol. Give me the weaker and strung out POS over that outcome.

As Joe/Chicago Storm mentioned, there's a lot of moving parts with the setup, so you're going to see plenty of variance in the guidance. Getting the flow to slow down enough for a digging strongly negatively tilted wave (like 00z Euro op), level of phasing, or lack thereof, etc. Those are all big question marks and handling all the complex features will vary greatly with small changes in other conditions. Re. your question about the 06z GFS and GEFS, think of the operational models as one of the ensemble members. That's honestly a good thing to see the difference between the operational and a sizeable portion of the ensemble, to give you an idea of the full spectrum of possible outcomes and see how the more robust members are handling the evolution differently. The GEFS has often had an issue holding too close to the operational. Definitely wait and see mode until later in the week.

The 12z continued on that theme, focus for a possible wintry threat shifted to Friday night-Saturday. The phasing the 00z run showed seemed like an unlikely evolution vs. most of the other guidance members. Sent from my SM-G998U using Tapatalk

Your last good clipper season was 2017 if I recall right. I remember there were some good ones in December that hit WI and MI. Sent from my SM-G998U using Tapatalk

Since 2009-10 is the only moderate to strong Niño winter since 1950 with above normal snow across the LOT CWA, not particularly optimistic for a snowy winter locally. That winter was a highly west based El Niño that peaked at 1.5 ONI and it had record strong AO/NAO blocking. The issue for us is that in means, El Niños are more conducive to +PNA, so that when it does get cold, you have more of a CAD or clippers vibe vs. moisture laden systems. Need to cash in if you do get a good southern stream wave or two. 2015 had the November 22nd system and most of the metro *just missed* on the late Feb event that slammed the south suburbs and especially northwest Indiana. I think if an element is going to diverge from the pre-season expectations (mild, and below average precip and snow), it'll be temperatures, especially if we get some good periods of blocking assuming the SPV isn't too strong (which appears possible in a -QBO/-PDO). Overall, outside of the super Niños (>2.0 ONI), the data is much more of a mixed bag for temps in moderate to strong Niños (1-2 range in the ONI). The challenge with temps is that if snow ends up on the low side, need favorably timed snow cover leading into cold snaps to get good periods of negative anomalies. For this reason, I'd still lean toward temps ending up above normal. Given the crappy winter we had last winter, here's hoping for an unlikely 2009-10 like outcome to this winter.

Will be back posting more regularly in here soon. Sent from my SM-G998U using Tapatalk

Just hit 97 at the top of the hour, bouncing around a bit on the real time sensor data we can access at LOT. So after hitting 97 it's back down to 96 at the moment. This behavior has been typical the past 2 days. Sent from my SM-G998U using Tapatalk