12/03/2009-12/04/2009 Winter Storm

[Robert Dewey]

11/29/09 12z UKMET shows a 993mb low across LA by 12z 12/02. The 12z GEM very similar in location, although not as deep (997mb)... eventually bringing this low ENE toward the OH/PA sate line by 12z 12/03. There appears to be a decent amount of cold air to the NW of this system, so we might be looking at our first snowstorm for areas of the Great Lakes and Northeast.

 

[mpearce]

I live in Cleveland, and I'm really looking forward to getting some snow finally. I notice you're in MI. Think Cleveland will be on the warm side...or do you think we'll get some snow? I'll be looking for residual lake effect after it passes...but may be more toward western NY possibly.

-Mat

 

[Robert Dewey]

It's too early to early at this point. It could be anything from a Chicago snowstorm to a NY snowstorm (or none at all), depending on if/when/where phasing between the northern stream and southern stream energy occurs.

 

[Danny Neal]

Last Tuesday GFS painted a < 990 low sitting over North-Central Indiana with Chicago being right in the thick of a NE flow off the lake and sub freezing temperatures. Definitely looked like I needed gas for my snow blower. As the days progressed the GFS brought the low further and further toward the Southeast and now it looks like by 00Z THU a 996 low sits right on the TN/NC border. Once again it is fascinating to watch the models run by run.

The new (18z) NAM is coming in now, but the 12 Z painted the low further to the west on the AL/MS border. Which, if I am interpreting this correctly, will throw the low up through WV and VA.

The jet will pick up this low and either send it for a ride into the NE or shear it apart.

I like to read Tom Skillings blog as he is a great teacher if nothing else. 12 of his 14 model forecasts predict measurable snow in the CHI-metro area within the next two weeks. Greatest being 8.1 inches. They also paint an 88% chance of measurable snow between the 4th and 10th. I know he uses the GFS a lot and that would match up with his "bottom left" picture http://weblogs.wgntv.com/chicago-we...g/2009/11/november-mild-spell-running-ou.html Since I am far from good at predicting winter storms I like to use Skilling as my reference and try to learn from it.

EDIT: I guess I should have read a little further on his blog:

10 of 12 recent computer runs -- 83% -- indicate measurable snow here in the coming 2 weeks
Weather history puts the chance of measurable snow (0.1" or more) in December's opening week at 65% and the chance of an inch or more of snow at 43%. The odds may end up a bit higher this year if recent computer projections verify. Ten of the 12 most recent runs of the National Weather Service's Global Forecast System (GFS) forecast model -- 83% -- indicate the potential for measurable snow. An average of model snowfall estimates over the next two weeks comes to around 4" -- but individual model projections range from nothing to as much as 8.1" between now and Friday, Dec. 11.

 

[rdale]

Interesting that he only uses the GFS... Given its horrible track record with cold air intrusions, even so far this season, that's surprising to me.

 

[rdale]

New NAM is MUCH farther west, the 12Z Canadian GEM had started the trend but this takes it way too far for any Michigan snow, with all temps well above freezing even with nearly a half-inch of QPF!

 

[Robert Dewey]

New NAM is MUCH farther west, the 12Z Canadian GEM had started the trend but this takes it way too far for any Michigan snow, with all temps well above freezing even with nearly a half-inch of QPF!

The latest 0z UKMET is fairly similar to the 0z NAM. At 72hr, UKMET is slightly colder than the NAM (-2C at LAN), more in line with the 0z GFS... but since that's the last time step, I can't see whether the warmer air continues to slide westward as shown by the NAM.

EDIT: 0z GEM fairly similar to the UKMET / GFS and would be ideal for good snows over IL/IN/MI. NAM seems like the odd man out, but with the westward trend I wouldn't rule it out.

 

[Joel Wright]

Looks like the area of snow with this system will be confined to a fairly narrow band on the west side. Still a bit on the early side, but that's the way it looks right now.

Taking a blend of all of the model forecasts over the last few days, I'd place the best chance for accumulating snow from near St. Louis, to South Bend IN, to Saginaw MI. Looks like a good lake effect snow machine could kick in after the storm passes by for much of the Lake areas, as deep cold roars in from the northwest.

 

[mpearce]

Looks like a good lake effect snow machine could kick in after the storm passes by for much of the Lake areas, as deep cold roars in from the northwest.

Thats what I'm hoping for here in Cleveland. The traditional snow belt areas usually pick up a very healthy dose of snow on the first LES event of the year.

 

[Robert Dewey]

12z GFS and 12z UKMET are fairly similar, particularly with thermal fields (not sure how well the UKMET does). 12z NAM still trending westward.

Either way, even if the GFS and UKMET verified, heavy synoptic snow might be hard to come by for areas further east than western MI... as 850mb Ts are still in the 0c to -2c range, which definitely isn't optimal.

 

[rdale]

NAM still running considerably warmer than GFS, so that's not much help. Canadian has now shifted more to the east, closer to the mountains (still no help.) But that could assist in some LES for other parts of the state.

 

[Joel Wright]

Well, it's pretty clear what the outlier is lol. The NAM is hands down the furthest west with the track. It is being relatively consistent, which is a bit startling.

GFS remains pretty consistent too, but is further east. This is much closer to the Euro and UK though.

Given the time of the year and the track record of early systems hedging a bit further westward than earlier forecast, I'd side with a slightly westward track of what the GFS indicates. This still places the best snows from about St. Louis/Springfield IL, to the south side of Chicago/South Bend IN, to about Bay City/Saginaw MI.

This storm system certainly doesn't have an abundance of cold air to work with, so the band of snow will likely be fairly narrow. That only makes it more interesting right?

 

[Robert Dewey]

NAM still running considerably warmer than GFS, so that's not much help. Canadian has now shifted more to the east, closer to the mountains (still no help.) But that could assist in some LES for other parts of the state.

12z UKMET actually seems to be a good middle-of-the-road solution. Not as far west as the NAM, and not as far east as the GFS.

 

[Ryan Wichman]

Still a bit far out as the northern stream of energy is still being sampled by the NA UA network. Its always interesting to see how the models try to phase the northern and southern streams together, most appear to be doing a reasonable job this time. But I am leaning towards a UKMET/ECMWF/GEM solution which are generally in the middle of a westerly NAM solution and an easterly GFS solution. There have been a few models trending towards that westerly NAM solution, we'll see how much those change at 00z.

I'll be keeping a close eye on this event. Solutions from the models should start coming together even more tonight with the 00z run. Update then.

 

[Robert Dewey]

18z NAM is weaker / further east... It's also amazing how dry the models are on the cold side of the system. At best, 18z NAM would have 100 mile-wide stripe of 4-6 inches tops. Not bad for this early in the season, but not that impressive either. 12z GFS is even worse; 2-4 inches over portions of IN/MI.

Unless models start bulking up the amount of QPF generated on the cold side, this will probably be nothing more than a nuisance storm.