RCNYILWX

All-timer save worthy

24-hour captures the defo for northern IL but misses the front end snow Monday night into Tuesday morning.

12z EPS modeled pattern for next weekend vs. December 2009 H5 composite anomaly. Deeper -PNA forecast but otherwise pretty good match with 2009.

Not surprised at all to see the NAM that amped at this range. Front end thump with the WAA has looked decent for a while - the air mass isn't cold but cold enough.

Unfortunately ILX has been using these maps in their graphics too.

The EPS has been very steady the last several runs. Sent from my SM-G998U using Tapatalk

Feel better about avoiding that insanely sharp cutoff March 3rd had. Sent from my SM-G998U using Tapatalk

The GEFS mean has had a gradual tick west, agree, while the EPS mean has generally been pretty consistent with the SLP track. With a good antecedent cold air mass, we'd have a little more wiggle room on the track. Sent from my SM-G998U using Tapatalk

Looks good for an inch to maybe two in spots. Sent from my SM-G998U using Tapatalk

The GEFS actually likes interior northern Illinois down to west central IL more - definitely been consistently west of the op. Should see a tightening of the spread the next couple cycles. Sent from my SM-G998U using Tapatalk

Another example of the importance of the ensembles at this range. The east coast system this weekend is a good case in point - there's still been noteworthy run to run swings by the operational runs in the last few model cycles.

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).