RCNYILWX

Recall March 2019 flooding from Nebraska to NW IL after that bombing low. Sent from my SM-G965U using Tapatalk

The NAMs look like a toss for Wednesday if the foreign guidance comes in farther north. 18z Euro had supported another 1-3" I-88 and south or thereabouts. Sent from my SM-G965U using Tapatalk

About 2.5" here measuring in the front of my house where I had shoveled out Saturday's snow. I'm assuming about 2" is from this evening with the band just north of my area this afternoon. Sent from my SM-G965U using Tapatalk

Puffballs here (southeast Naperville near DuPage/Will border) underneath the band, +SN but a nice gentle deep winter evening. Stacking nicely. Edit: photo of my backyard for reference, the snow (largest dendrites around dime size) is stacking vertically on that chairback, showing how it's ultra light high SLR fluff and also no wind to disturb it. Basically perfect conditions in this band to max out efficiency. 00Z DVN sounding has 13kft deep DGZ with lapse rates >7C/km above the 700 mb centered f-gen zone.

Call in your latest report to the office if you haven't yet, could always use additional reports from the city Sent from my SM-G965U using Tapatalk

^Didn't age well [emoji38] Sent from my SM-G965U using Tapatalk

Just called in your report to the office. Nice dendies here but only a dusting since we spent much of the night north of the band. The ultra high ratios you got might bode well for later. Sent from my SM-G965U using Tapatalk

Ironic, or serious?

Him winning in TB doesn't have the same resonance. If he was still in New England and won, I'd be seething. Also, good to see Bellichick getting smacked down for being arrogant. Sent from my SM-G965U using Tapatalk

Trust in the pattern moving forward. May not cash in immediately but think we'll get at least a solid event or two. It hasn't been what some earlier model runs showed yet, though the amount of cold air and chance for decent baroclinicity should win out eventually. And at the least, the chances of lighter snow we're getting for now are better than the nothingness we had for 2 weeks to start January remember. Sent from my SM-G965U using Tapatalk

Revisiting this, some of the early HRRR/RAP runs and to a bit lesser extent the NAMs and HRWs clearly were far too aggressive. Had thought 2-4" was attainable across a good chunk of the CWA in expectation that the ratios could perform even outside banding. This was before it started to become more clear that this would be one of those fairly common setups where only in the banding would ratios perform to their capability and the CAMs were overdoing QPF. It appears that the CAMs were reacting to mesoscale banding and distributing this QPF over much too widespread an area and were in general too wet. These are tough forecasts because the globals don't necessarily do as good a job picking up on the f-gen banding, while the CAMs do but might be too aggressive in doing so. Plus the ratio question really takes being precise in ascertaining where banding will set up to forecast the localized 15-20:1 ratios while the rest of the area comes in close to 10:1.

The band from BRL to VYS is where it's at for getting the high ratio dendrites. It looks like that should slide across the southwest burbs and then probably south of downtown Chicago. Might be close to getting clipped by the band at my location. Sent from my SM-G965U using Tapatalk

Ratios in these situations are always tied to how well the omega is aligned with the DGZ. If there's a mismatch, you get pixies, no matter how deep the DGZ is. Today is conditionally favorable for 20:1+ ratios because of the deep DGZ but it looks like it will be temporary and tied to the somewhat transient f-gen banding. Wherever ratios end more around 10:1 today is a good case study for the flaw of the Kuchera method (and also underscores how ridiculous the WeenieBell maps are). Because it's based off the MaxT from the surface to 500 mb, and the whole column is very cold, there's no way for the Kuchera ratios to not be high today and in other events with cold sfc temps, which means caution is advised for all events moving forward with snow maps. The Cobb ratios found on PSU BUFKIT site are better for a day like today because the Cobb ratios are based off how strong the lift is and how well aligned it is with the DGZ. Kuchera is better for more marginal thermals or when it looks like climo ratios are better than 10:1 for a given event.

Both the HRRR and NAM place the banding signature a bit north of where the low-mid level f-gen has been maximized on recent model runs, which is where you'd expect it. Sent from my SM-G965U using Tapatalk

I'm surprised they didn't go into Indiana with it, which may have had to do with IWX and IND not issuing for any of their counties. Haven't seen that quick of dampening eastward within the CWA on the guidance. There's a little bit of good and a little bit of less good from what we know so far. Clearly they didn't rely solely upon global guidance and ensembles for QPF and snow output. On the other hand, there's support for going farther north and east with the headline. My guess, if the AVN AFD is a clue, is that we wanted to go farther north but DVN didn't even want to issue anything. The map looks weird enough with LaSalle in and not Bureau and Putnam and points west. Imo having included LaSalle could also have included some counties farther north and east in the metro without yet putting Lee County in. Sent from my SM-G965U using Tapatalk

The truthers would say this is a combination of a massive uptick in suicide and a bunch of older people with co-morbidities all decided to die in one year Sent from my SM-G965U using Tapatalk

12z NAM valid 22z 800-600 mb 2D f-gen from FSU site http://moe.met.fsu.edu/banding/ Sent from my SM-G965U using Tapatalk

No because that's a common NAM problem in Arctic air masses. The GFS has a much lower QPF output but it's completely saturated through the DGZ. Sent from my SM-G965U using Tapatalk

Pivotal Kuchera Sent from my SM-G965U using Tapatalk

Yep, guaranteed based on the Aviation AFD that they'll be taking them up. Sent from my SM-G965U using Tapatalk

Nice tidbit here from our 18z TAF Aviation AFD Sent from my SM-G965U using Tapatalk

I'm liking a 2-4" range for the LOT CWA. Sent from my SM-G965U using Tapatalk

While it's possible that the northern tier ends up with somewhat less snow, I doubt anywhere in the CWA gets shut out tomorrow. Sent from my SM-G965U using Tapatalk

Award for most weenie 12z run goes to the WRF-ARW Sent from my SM-G965U using Tapatalk

I think there's upside potential above our official 1-2, locally 3" forecast, for reasons that have been discussed (high SLR, steep lapse rates, low and mid-level f-gen). Now that the HRRR has gotten more realistic, the 06z NAM runs probably represent a reasonable best case scenario for now. Good to hear the Euro bumped QPF on 06z run. Sent from my SM-G965U using Tapatalk