12/11-12/13 FCST Midwest

[Ryan Wichman]

I could be jumping the gun a bit on making a forecast thread for this event. But all signs are point towards a potent winter weather system impacting the central parts of the United States during this time frame. Likely moving on and impacting the east coast as well.

The GFS and Euro have been consistent, albiet only for the past 3 runs, in showing the initial signs of a major weather event to unfold. First the upper level jet is progged to be > 150 kts, carving out a deep trough and aiding in significant lift. The location of the low level cyclogenesis, based on the aforementioned models, would create a situation where gulf moisture feed would be unmolested for heavy QPF.

No need to get into details on any specifics, such as totals or locations of any snowfall at this point in the game. Just fun to get the ball rolling on a good discussion as the event draws closer.

 

[DWest]

I've been reading the KLSX area forecast discussion for the past couple days and they have been keeping an eye on this system; at the moment it seems that there are rather large differences between the ECWMF (which tracks the low into the Ohio river valley) and the GFS, which brings it near the Memphis area by the weekend. Could pick up some pretty good snow in my region of Missouri if the GFS solution verifies. Either way, going to be extremely cold for this time of year after it passes...forecasting a high of only 25 on Sunday.

 

[Jesse Risley]

This one's going to be tough to nail down for at least several more days. I noticed last night that the previous run of the ECMWF (prior to 00z today) had the low taking a more southerly route, closer to the Ohio River valley, which was at least somewhat more synchronous with the 00z run of the GFS, which is still maintaining a far more southerly track.

If the more southerly route (of some sort) verifies, then obviously the axis of heaviest QPF will shift quite a bit southward. It doesn't appear that paltry moisture availability will be a problem with this system.

 

[Brent A. Clair]

The 12Z GFS does a weird take, as it drops the energy of the NWPAC low early on, and then forms the low over NE/KS, an atypical low setup that I wouldn't think would develop that fast. But then, cyclogenesis was not my best subject! On the bright side, the GFS does put down some nice snow potential for STL north

 

[Robert Dewey]

I'm going to go with a further NW track. 12z Canadian has the sfc low over NE IL at 12z SUN... and the GFS has been trending that way. Not sure I'd go that far NW, but still could be a "west of the Appalachian" play.

 

[rdale]

Ensemble Euro is a little more middle of the road, but it just doesn't look like a typical storm path. AccuWeather already is going all-out for my area, specifically calling out Detroit for major problems, but I'm not onboard with that at all right now.

http://www.accuweather.com/blogs/news/story/42618/major-snowstorm-could-hit-the.asp

 

[Robert Dewey]

Even being in the 144 hour range, I'm not surprised by their overconfidence. I think it's a possible outcome... but not any more likely than other solutions suggested by NWP.

 

[rdale]

If the 18Z GFS is perfect, they nailed it.

Which means...

 

[Robert Dewey]

As of now, 0z/6z GFS comprises of the farthest east solution as far as I can tell. I'm not really buying that. I recall reading somewhere (DTX AFD) awhile back that storms will usually ride east or west of the Appalachians - rarely will they cross or ride along the spine. Rather than bring the low west of the Appalachians and redevelop it along the cost as is common, the GFS just trucks it ENE. Climatologically speaking, I'm not sure how true that is...

 

[Chris Carter]

What seems to be key is the blocking right now over Euro which is causing the lake effect snow right now, the system went up the east coast and now back tracked its way into eastern canada. This blocking will continue for the next few days. The Euro and Canadian models don't really go in line with this blocking pattern. But the GFS does go along with the blocking. So it comes down to whether or not the blocking will break down or stay in place.

But in anycase, it seems that there are three major systems coming down the stretch for the holidays, this first one is coming this weekend to early next week, the next two will be more southerly than the first, so in my opinion who ever doesn't get affect by snow the first time has two more chances after this one.

 

[Robert Dewey]

12 GEM has slid further southeast, 12 GFS has slid further NW. I think the solution lies somewhere in between. I'll go with a Bowling Green, KY to Buffalo, NY track as of right now. Both models are fairly consistent with a strong high building S into the Northern Plains, creating a strong pressure gradient and expansive area of strong winds at the surface.

Will be fun to look back and see if my track is a complete bust

 

[Ben Kossow]

Surprisingly no discussion here this morning. Models have shifted considerably. GFS is now much farther north across southern Wisconsin and through Canada before deepening and slamming the northeast. Should be an interesting 24 hours with the models.

 

[rdale]

There really isn't much to "discuss" when we're still in a major guessing pattern... When the ECWMF is the model with the most consistency issues, that's a sign

 

[John Vandehei]

I saw that northward shift too. That's an awful dramatic shift. I'd like to see at least one more run advertising that same track before I buy into it. I've seen the GFS do this before; advertise a certain track for a few runs, then make a dramatic shift or even eliminate a major storm completely for a single run, than move back to the previous track on a later run.

 

[Ben Kossow]

True, but it does make for interesting AFD reading. Seeing more interesting prose in there than normal. With all the standard winter uncertainty and this other system sprinting through tonight, you're right...it's anyone's guess at this point.