RCNYILWX

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

I'm tracking the progress of the snow since my family was able to take off on time out of ORD, scheduled for a 527pm landing at HPN. Should be a fun landing for them. Anyway, interesting to follow the terminal dopplers over the past hour since the 0.5 deg scan on both OKX and DIX was too high to account for the very dry low levels. The fact that 25-30 dBZ at 4.5-5kft AGL on the NWS dopplers wasn't quite enough to punch through for a time shows how potent that low level dry wedge was, which lines up with 25/1 ob at HPN at around 4pm/21z. Sent from my SM-S936U using Tapatalk

Anyone well versed in how flights into HPN get affected on the incoming portion of a snow system? My family is out here in the Chicago area and they're supposed to take off at 2:13pm local and land at 5:26pm EST tomorrow. It's a little tricky with how the snow will be moving in by that time, vs. well underway regarding delays and cancellations. Sent from my SM-S936U using Tapatalk

It's basically the CAMs and RAP against the globals, with the GFS the farthest northeast of these. Wouldn't be surprised at a compromise in which the better f-gen banding and accum axis is indeed farther southwest, while farther north and east we get several hours of pixies accumulating to an inch or two. Could certainly be wrong but my current lean is away from a complete whiff with the first system. Too soon to write off Saturday for adjustments back (a decent % of 06z EPS members still had solid snow up into parts of the metro).

Pretty much inevitable there would be some form of pattern relaxation. The saving grace from probably not getting into a lengthy torch is the WPO is forecast to remain strongly negative, which keeps cold air discharge going into our source region. The EPO may head back toward neutral heading into Christmas week and then perhaps back to negative thereafter. I think with the likelihood of new snow on top of the melted and consolidated snowpack through this weekend and then the deep freeze for a couple days, if we can avoid a high dew point rain event, snowpack retention should be decent before a true pattern reload commences. Also with the -WPO that means CAA behind fronts should be fairly robust. Milder more zonal patterns often end up cloudy which typically isn't effective at melting much snow this time of year, again unless you get a couple days of high dew points. Even at over two weeks out, I'd lean towards Chicago having its first official white Christmas in a while. Sent from my SM-S936U using Tapatalk

WSSI suggests that DVN upgrading some counties to a warning was a very aggressive move. Given that we had a warranted daytime warning event a week ago, it's questionable if the possibility of getting a narrow band of 6-7" of snow on a Saturday evening-early Sunday warning is sufficient to prompt a warning. Sticking with a WWA seems like it would've been fine. We'll see how it goes. Sent from my SM-S936U using Tapatalk

Call it 8.1" for me. Nearest CoCoRaHS (Naperville 2.5 ESE) had 8.5". Looks like about 8-9" was the range in this part of the southwest burbs. My largest (and favorite) November event since I've lived out here and largest overall for my area since Feb 1-3, 2022. The most recent big late November event in 2018 was slop in the southwest burbs until the very end. Sent from my SM-S936U using Tapatalk

I measured 7.3" by me, first time measuring all day though so there was definitely compaction. I don't have great places to measure since I have a big tree out front and also in back of my house. The Naperville 2.5 ESE CoCoRaHS is probably only a little over a mile from me so I'll see what they come up with in the morning. Sent from my SM-S936U using Tapatalk

Filled in nicely again, maybe another 1 to locally 2". Gonna measure later for a storm total. Has to be over 6" here too. Sent from my SM-S936U using Tapatalk

Legit SN to +SN out here in my part of Naperville (near DuPage Will border). Sent from my SM-S936U using Tapatalk

The top end range on the "official NWS forecast" graphic is the 75th percentile of the NBM distribution and the low end is the 25th percentile. Point and click is still quite high and possibly/likely overdone and our (LOT CWA) overnight forecaster did some work to rein it in a bit even. Looks like DVN made less adjustments to the initialized data so they have a large area of 12"+. I can say, speaking for my office, that we all strongly dislike the probabilistic winter page but unfortunately we don't have control over what's displayed on it.

I'm off through the weekend so will get to experience this one from the weather enthusiast side. In all honestly, haven't looked at model data since my shift ended this morning lol. How are trends for Chicagoland? Sent from my SM-S936U using Tapatalk

The last two EPS runs have been mighty impressive, which is usually the guidance suite you want on your side. Too far out to be super confident but if we don't see any sig backsliding, chances are pretty decent even at this lead time for the biggest synoptic event in this part of the subforum since the two weeks of winter in January 2024 (which isn't saying all that much given the lack of snow last winter). Sent from my SM-S936U using Tapatalk

I put together a long range pattern thoughts document for LOT staff a few days ago regarding the the impressive agreement in a cold and potentially active pattern with some staying power. It'll be primarily -EPO driven at first but then with the stratospheric warming/SPV stretching event ongoing, that tends to translate with blocking also developing in the AO and NAO domains. If we can keep the PNA neutral to negative, could set up for a rare snowy December for a good chunk of the region. For Chicago since 2010, the only Decembers that had both above normal snowfall and below normal temps are 2010, 2013, and 2016. Below normal temps but below normal snow occurred in 2017 and 2022. I know that Detroit had a very good December in 2017 from a much more favorable clipper track there. Sent from my SM-S936U using Tapatalk

Based on how much discussion there was on social media of the NWS snowfall maps with the huge ranges, was that a topic on here and did anyone attempt to address what those ranges represent? I'd be happy to, just don't want to rehash if it's already been covered. Sent from my SM-S936U using Tapatalk

Also if you're a Chicagoan who likes snow, getting in on any heavy LES prior to the halfway point of November is a big win and extremely rare (I don't recall any events in my time here). I believe there may have been one back in 2000.

This. As this case shows, it's tough to get things just right for a certain location with lake effect on the south end of the lake even when there is stationary banding. The jackpot zones are almost always going to be narrow. It's what makes events like Feb 14-16, 2021 rare for the city.

Just leaving a busy evening shift. TAF verified (edit: at MDW, need ORD still) [emoji123] Sent from my SM-S936U using Tapatalk

The potential is def there for a very favorable low topped supercell sig tor environment, particularly if the more aggressively moist HRRR/RAP depictions pan out. Glad SPC bumped up the tornado threat. Other than being a little surprised Bentley went right to the 10% hatched (vs. unhatched 10% or perhaps a smaller 5% tor) given questions on the specifics with the moisture and the resulting 0-3km CAPE, nice outlook and well written discussion. I'm liking near/south of the IL and Kankakee River in LOT CWA, which gives more wiggle room south of the warm front given the ~40 kt SSW Bunkers right mover vector, and low hodographs have generally looked a little better with southward extent in the warm sector within the CWA. Might see about chasing (for the first time since 2016) since I won't be called into work after working 7 shifts in a row.

Timing currently looks unfavorably late locally (LOT/Chicago metro) on Friday regarding any substantial severe threat. Since these deep negatively tilted troughs/closed ULLs often trend slower, the system slowing more into Sat may be the best path to getting some severe into the CWA. Sent from my Pixel 9 Pro using Tapatalk