Chicago Storm

We needed a good thread. Been years since a high quality one.

This run of the NAM was first hurt, but then saved by big changes at 500mb. The northern wave ends up less phased with the southern wave, thus is slower and digs more. However, the 2nd northern wave diving into the Lakes later on ends up phasing with the original northern wave. This is why the run was meh early on, but then came in with a late save. .

Still coming in, but only 1-4” by Wed evening is not good. .

Na, SLP is weaker and east. More of a diffuse area of SLP. .

It’s not gonna be pretty. .

It has the 2nd best 500mb NH verification score, so yes. .

Ukie is the furthest south.

18z Euro...

18z Euro coming in SE and weaker yet again.

6:1 to 10:1 will be the likely range, do to the marginal SFC temps.

RGEM still getting into range, but will also be well south/weak.

That's not fully how it works anymore. NWS heavily uses NBM now, which Ricky could go into more.

They have been fairly bad much of this season.

lol WPC disco... 19z update: The UKMET remains too far south and the CMC elongated more positively in the orientation of the trof Wednesday to delay it even further with very little/no interaction out of the Arctic stream to continue rejecting the UKMET/CMC from any preference at this time. The 12z GFS remains steadfast to continue to heavily favor it in the blend. The 12z ECMWF continues to be generally weaker with the inner core of the developing upper low/hub coming out of the MO Valley, keeping it south and east compared to the GFS/NAM and even compared to the GEFS/ECMWF. Interestingly, the Arctic shortwave continues to trend sharper/further south in all guidance. So will not break from initial preference, of the 12z GEFS/GFS/NAM/ECMWF and 00z ECENS through 26.00z and remove 12z GFS afterward weighting heavy to GEFS.

These new headlines issued by LOT/MKE have huge bust potential.

18z NAM will definitely be south/weaker.

12z EPS

Most guiddance doesn't have higher ratios until closer to Wed morning, and by then thing will be wrapping up shortly after.

Unfortunately.

hlcater gonna be the first crash and burn.

I'd be more concerned with how 500mb plays out for stronger/NW or weaker/east...than worrying about being on southern gradient.

Pretty much.

For reference for ORD... The last 10”+ snowstorm was Nov 20-21st 2015. (11.2”) The last 12”+ snowstorm was GHD2 in 2015, and the previous before that was GHD1 in 2011. .

NAM with only 6:1-10:1 ratios much of the event, due to the marginal surface temps most of the time. 12:1 with that QPF would have been like ~25” .