RCNYILWX

Assuming they cracked 12" for the event, it'll push them into a top 10 snowstorm overall. Sent from my SM-G965U using Tapatalk

Www.coastwatch.msu.edu/twomichigans.html Sent from my SM-G965U using Tapatalk

Consistency of the Euro for several model cycles is enough for me to give it more weight than the other op models in not being too concerned about some of our warning counties not verifying. Sent from my SM-G965U using Tapatalk

We're doing a Q&A on LOT FB and Twitter between 610 and 7pm if anyone is interested in asking us questions. Sent from my SM-G965U using Tapatalk

If you want to see I think the most extreme solution yet for this event, check out the 18z HRDPS on Tropical Tidbits. Pure model porn lol. 2"+ qpf amounts in the max axis over northern IL. Sent from my SM-G965U using Tapatalk

I think this map looks pretty reasonable on how narrow the heaviest snow axis is likely to be given the intense fgen signal being modeled, if not the amounts. Though the ferrier correction is supposed to be good for low ratio events, so the attached 3km NAM map could be a fairly realistic representation. Similar to the 2015 storm, I buy a narrow area of 12"+ amounts. I think the Euro is too widespread with the huge amounts, but we'll see. This is a good tweet from John Homenuk (former board member Earthlight) about the fgen compnent: https://mobile.twitter.com/jhomenuk/status/1066397512519610369 The models do a good job on picking up on the signal for intense fgen and negative epv driven banding but exact position is something that is really tough to pin down and is more of a nowcast item. Sent from my SM-G965U using Tapatalk

Also since their observers very frequently overdo the wind speeds, something we've never figured out what they do on those hourly obs considering that they have an AWOS. Sent from my SM-G965U using Tapatalk

It's >50% confidence in attaining local warning criteria within the county. I'm not a huge fan of lowering headline issuance criteria too much but I think it's close enough to justify it in this case. The winds look to be a major issue combined with the heavy wet snow and even if lakeside Chicago struggles to accumulate, winds straight of frictionless could be strong enough to cause wind damage. Also lakeshore flooding a significant concern. Sent from my SM-G965U using Tapatalk

My office added Kane and Lake to the watch. Having been at the office I can say there was a friendly discussion on whether to include Cook and DuPage and LaSalle. I personally would've included those counties in the watch with the support of some of the models and it being so close to the event and the major travel impacts likely, despite our official amounts being below warning criteria of 6"+. There's certainly very high bust potential, especially in the city of Chicago, particularly near the lake with strong winds from the lake. Have to think the Euro is overdone because it's just so extreme but the more tame previous few runs would still be high impact. DVN is going with a warning, ILX and MKX staying with watch. We'll see how this all goes later today. What an incredibly challenging forecast, likely owing to the complex evolution of the parent wave and ULL and degree of phasing and where it occurs. Edit: We did end up going with LaSalle County in the watch, decision was probably helped by DVN going warning to Bureau County.

I'm not but I'm here geeking out lol and one of us will have evening update tomorrow. Sent from my SM-G965U using Tapatalk

Buried is actually an understatement from this run lol. Sent from my SM-G965U using Tapatalk

Clear as mud. To make matters even more fun today for the wfo's, there was a nationwide data outage, so the day shift had no new model data ingested to create the forecast grids. Sent from my SM-G965U using Tapatalk

Strongest 925 mb winds modeled in a winter system here since before...2/24/16? Otherwise don't recall 60-70 kt 925 mb winds (as shown at 06z over southern LM and Cook county and NW IN) being modeled. Sent from my SM-G965U using Tapatalk

Much better phasing at h5 led to that more northeastward oriented sfc low track. Sent from my SM-G965U using Tapatalk

The 00z consensus sfc low track is pretty climatologically ideal for heavy snow in the Chicago area from a west to east/WSW to ENE tracking system. Not surprised given that parent wave is still out in Pacific but what a shift from earlier runs, especially the more amped/NW ones. Plenty of details to sort out including potential for further shifts of surface low track, but if we can get something close to average of the track of 00z op runs, will feel good about a swath of heavy snow here. As has been posted at length about, winds look very impressive. Sent from my SM-G965U using Tapatalk

Total precip as snow on 12z Euro. Probably figure ratios averaging solidly less than 10:1, especially lakeside in Chicago. Sent from my SM-G965U using Tapatalk

Extremely impressive moisture plume modeled on the 00z Euro with cold sector pwats generally AOA 0.6" and near/above 1" pwats feeding into the trowal and cold conveyor. Sent from my SM-G965U using Tapatalk

Thanks! Sent from my SM-G965U using Tapatalk

LOT winter outlook is posted on our website: https://www.weather.gov/lot/Winter201819_Outlook Sent from my SM-G965U using Tapatalk

The models also seem to be responding to the strong west based NAO block. Sent from my SM-G965U using Tapatalk

We focused on weak Niños but including lower end moderate events doesnt change the picture much. This graphic below is interesting because it shows the findings well that outside of the strongest Niños, a majority of episodes are near to below normal for the sub forum areas. Edit: The other thing is that despite the Niño SSTs already being in place, a sufficient atmospheric response hasn't been noted yet to declare the event. With it being only 11 days from met winter starting, it probably doesnt matter at this point whether the ONI reading is in the weak or low end moderate range w.r.t. magnitude of ENSO forcing, assuming it occurs, it'll be a weak event for all intents and purposes for Dec-Mar period.

I'm planning to post the LOT winter outlook to the web and social media on Wednesday. We're going with near normal temps, to possibly below normal, near to below normal precip and near normal snowfall. Based off 81-10 climate normal period, the middle 50th or 33rd percentile of avg temps for winter in Chicago is in mid to upper 20s and snowfall is in upper 20s to around 40" (~27-28" to ~40-42"). These can kind of be seen as the typical ranges instead of focusing exclusively on 26.4 for normal DJF avg temp and 36.3" for normal seasonal snowfall. In the 12 weak Niños since 1950 as defined by CPC, 11 had near to above normal snow in Chicago. 2002-03 was the lone exception. 9 of the 12 were near to below normal temps and 8 of 12 were near to below normal precip. Our main thinking is that a solidly warm winter (near/above 30° DJF avg) is less likely. Snowfall is certainly tricky and cant rule out a 02-03 like scenario here despite our head start. The near normal in our outlook would probably fall into the 30s to around 40/low 40s part of the range. Looking forward to seeing response on here from those who read the outlook when we post it.

H/T to Hoosier for posting about that in the November thread. Figured I'd throw it into the climate section with the general interest about the first widespread snow accums of the season and them occurring so early. Sent from my SM-G965U using Tapatalk

Chiming back in after a long break. We won't put anything out locally (from LOT) until November but wanted to offer some prelim thoughts. Assuming we do have a weak Nino, the composite favors a cool east and warm west and a dry signal in this region. Interestingly the most recent Euro seasonal had this sort of look and the cold peaking in Feb like in recent weak to lower end moderate Ninos (02-03, 06-07 and 14-15). The change I would've made to the outlook would be to remove the low warm probs over southeast half of IA, southern WI, northern IL, far northern IN and southern lower MI and gotten rid of the warm probs in the northeast. The dry signal here is pretty reasonable from past similar events. Of course all it takes is one big dog or a few sig events to skew the seasonal snowfall, which is what happened for parts of the sub in 2014-15. Outside of GHD II, that was a cool and mostly dry winter locally.

Probably was them since I heard there weren't too many people out, funny coincidence. Did they say that I work for NWS Chicago? Sent from my SM-G965U using Tapatalk