Chicago Storm

Looks like 0z GFS will bump south with at least the overrunning portion. Edit: And likely main storm too.

COOP observer and NWS OBS sites are more the official route. CoCoRaHs is supplemental.

There were only ~3 EPS members that had the main storm this far north.

It does, but the 18z EPS goes out to 144hrs.

Cross referencing COD, looks the same as WxBell… .

18z GEFS mean...

Would hope that we have the overrunning portion sorted out by tomorrow at some point, and the main storm on Monday hopefully.

It has been exceptionally bad this season.

.

Fairly large changes on the 18z GFS.

you moved to cedar rapids?

well, that’s a wrap for here. .

The latter one is the correct one in this case. .

-D. .

The main storm potential has many factors involved, all of which obviously can make for a north/south shift. Some of the players involved are; The PV in Canada, ridging out ahead of the Western US trough, additional waves diving into the West later in the period, the quality of the main wave (elongated/strung out vs not), timing of the main wave ejection and more. The GFS for example is north due to the quality of ridging ahead of the main ejecting wave, as well as a much more consolidated Western US trough, with a main wave that is actually able to take on a negative tilt as it ejects into the Plains. On the other hand, one reason the Euro is much further south with the main storm is due the much slower timing and a much more elongated/strung out trough. .

12z EPS mean .

Depends on what portion of this stretch you're talking about... The overrunning portion or the main storm.

12z Euro

big dog or pass.

Several changes aloft when taking a look at things for the 12z Euro as well... -Lead wave on Mon/Tue is further north, and ends up tracking further NE overall. Also much more ridging out across S Ontario/Lakes/OV/MSV/Etc, due in part to aforementioned lead wave being north and handling of the PV in Canada. This is one factor in giving the overrunning portion a different angle and further north. -Main trough in the West is more elongated/strung out and is lagging/slower, thus you end up with a much slower and further south main system. It actually ends up as a very widespread spread the wealth storm.

12z Euro looking north early. Higher heights in S Ontario/Lakes/OV/MSV, and lead wave is further north when coming through. Also, Western US trough is more consolidated/organized, deeper and is less strung out/elongated. It won’t be the 12z GFS, but it’ll be a step that way.

12z GEM .

Several changes aloft when taking a look at things... -Lead wave on Mon/Tue is a bit further south, and ends up tracking further south overall. -PV in Canada is much further south, which helps shunt the overrunning potential south. -Main trough in the West is much more stung out/elongated and it slower, thus you end up with a much slower ejecting main storm system. Also ends up further SE than the GFS has it, do to a lot of what is mentioned in other points.

12z GEFS mean… .