Nov 28-30th Post Turkey Day Wintry Potential

[sbnwx85]

Last hour of the HRRR plus kuchera amounts. It’s making me a little nervous seeing how far north that warm air is budging in… and a potential dry slot.

[Baum]

^ somewhat expected. - perLOT AFD
 

THE INCREASINGLY FAVORED TRACK OF THE SURFACE LOW FROM WEST-   CENTRAL ILLINOIS TO FAR SOUTHERN LAKE MICHIGAN LATE SATURDAY   AFTERNOON AND NIGHT INDICATES THAT SNOWFALL QUALITY WILL   DIMINISH THROUGH THE EVENING HOURS AS LOW-LEVEL WARMING OCCURS   BELOW AN APPROACHING MID-LEVEL DRY SLOT. IT IS POSSIBLE THAT   AREAS EAST OF I-57 MIX WITH OR EVEN BRIEFLY CHANGE OVER TO   DRIZZLE DURING THE EVENING. THE BACK EDGE OF THE SYSTEM WILL   THEN DEPART LATE SATURDAY NIGHT THROUGH SUNDAY MORNING, ENDING   THE BROADER SYNOPTIC PRECIP POTENTIAL.  

[Sciascia]

Operational NAM cooking up another weenie run, especially for E IA/NW IL/SW WI. Hi-res NAM still high but a couple inches lesser.

[SchaumburgStormer]

6 minutes ago, Sciascia said:

NAM cooking up another weenie run, especially for E IA/NW IL/SW WI

Widespread 10-12+. Would be fun

[Harry Perry]

1 hour ago, frostfern said:

I don’t know what kind of ratios this is.  I prefer to look at 10:1 and bump it up a little in my head.  It’s hard to get 15:1 or better this time of year without lake enhancement.  WAA snow tends to be somewhat denser, at least in my area with E wind off the land.

I did read somewhere in one of the previous AFD’s that ratios would be as high as 16-17:1 which would be pretty impressive by November standards. 

[hawkeye_wx]

This evening's regionals/CAMs have not backed off at all.  In fact, every model so far has inched farther north. (NAM/3kNAM/FV3/RDPS/HRRR/RRFS)

[ChiTownSnow]

Fully sampled with tonights runs or tomorrow morning? 

[frostfern]

12 minutes ago, Harry Perry said:

I did read somewhere in one of the previous AFD’s that ratios would be as high as 16-17:1 which would be pretty impressive by November standards. 

That would be unusual.  I’m just used to dry layers below the DGZ screwing with flake size during WAA snow events with an east wind, especially the early part of the storm.  The good thing is this is a long duration event.

[nwohweather]

Shocked there hasn’t been a huge March north. I’d lean 2-4” for Toledo and 3-6” for places west of I-75 to the border

[Sciascia]

00z GFS nearly a carbon copy of 18z in terms of snow amounts

[Paulie21]

I think 8-10” is fair forecast. Thinking 16 hours + of snow. Averaging 1/2” per hour ish. Wherever this enhanced H5 band of UVV's lands will definitely have some higher rates/bigger flakes, liking I-88 to I-90 corridor (for now). Wouldn't rule out some stray TSSN in this weenie band.

[HillsdaleMIWeather]

Real Weenie Time 

[migratingwx]

9 minutes ago, Sciascia said:

00z GFS nearly a carbon copy of 18z in terms of snow amounts

00z vs 18z below

 

[TheNiño]

My contribution to this thread.

[michsnowfreak]

1 hour ago, Harry Perry said:

I did read somewhere in one of the previous AFD’s that ratios would be as high as 16-17:1 which would be pretty impressive by November standards. 

Ratios are what im interested in. A bulk of the snow will fall with temps of about 28-32, so even if it does end as rain as temps briefly climb above freezing Sunday morning here, I have to imagine a good blanket is laid down.

[andyhb]

18z EPS mean is 10" for the QC even at 10:1 ratios, pretty impressive considering I'd expect the ratios to be better than that through a good chunk of the storm. This will punch above its weight class SLP depth wise given the favorable dynamics aloft and very strong LLJ/WAA minus a lot of strong convection in the warm sector. Height falls look excellent on the 00z GFS.

[Radtechwxman]

Definitely worried about how north some hi res guidance is. Especially the hrrr/rap. It still has decent totals here but question snow quality especially in the latter part of the storm as low passes close or over. Hrrr/rap drag the mixing line north of me. Gfs/euro/nam keep it south. Tomorrow is the day to watch for trends. Hoping this doesn't start a north trend now. I think QC up to Chicago really going to cash in but a little nervous down here on I74 corridor. 

[hlcater]

Dont really see anything to dislike on the 00z runs. Gonna go with a potentially conservative guess of 8".

[sbnwx85]

10 minutes ago, Radtechwxman said:

Definitely worried about how north some hi res guidance is. Especially the hrrr/rap. It still has decent totals here but question snow quality especially in the latter part of the storm as low passes close or over. Hrrr/rap drag the mixing line north of me. Gfs/euro/nam keep it south. Tomorrow is the day to watch for trends. Hoping this doesn't start a north trend now. I think QC up to Chicago really going to cash in but a little nervous down here on I74 corridor. 

HRRR/RAP dry slot me but put down 11” of snow before that happens. That’s probably overdone. Final call: 9”

[Kaner88]

00z AIFS Op will be wetter in northern IL, upping total QPF above 0.75" compared to sub-0.75" the prior runs

[Radtechwxman]

Something that should probably be used for this event in a lot of areas is snow depth to see a more realistic depiction of what you may measure on ground. Kuchera and 10:1 maps aren't accounting for the compaction and melting from this very wet snow that will likely occur and are probably overinflated. Yes 8-10in may fall but may not reflect on ground after melting and compaction. 

[hawkeye_wx]

00z Euro...  This is about as locked into 8+" as my area ever gets.

[michaelmantis]

2 minutes ago, hawkeye_wx said:

00z Euro...  This is about as locked into 8+" as my area ever gets.

For the first storm of the season, coming out of a bad 2024-2025, all the signs seem to be good for IA, S WI, and N IL. 

 

[migratingwx]

4 minutes ago, hawkeye_wx said:

00z Euro...  This is about as locked into 8+" as my area ever gets.

[homedis]

Looking good. Curious to see how the lake will affect snow ratios in lakeside areas with the slightly onshore SSE flow, but thinking 1:10 average is reasonable. Final call 7.5” Lake Forest, I’ll be stationed here for duration of the storm. They got around 6” from the LES event a few weeks back so that would be over a foot total for Nov — quite impressive.

[KeenerWx]

On 11/27/2025 at 12:30 AM, KeenerWx said:

All things considered, with fail modes still on the table, feeling pretty good about 3-6”. For the fun, will place chips on 4.8”. 

Not much has changed from my thoughts locally over the past 24 hours. Hoping we hold steady, even as that dry slot influenced “custom screw zone” (cyclone, 2025) gets way too close for comfort. For a final call would expand the upper range and go 3-7”. Aside from total failure, I don’t see going below 3”. But imo would take a lot of things going right to get to 7”. Moving chips up a bit to 5.7”