11/30/2006 FCST: IL / MI / IL / MO / KS / OK (WINTER PRECIP)

[Brandon Sullivan]

Latest model runs continue to indicate a possible winter storm setup on the 29th through the 1st. Critical thickness data shows a favorable setup for accumulating snows. Thermal profiles show freezing temps at BG level, thus any precip that could fall would be able to be all snow. Post frontal precip would be changed to snow as low pressure builds into the area. Still a ways out, and models can't really agree, couple of hundred miles of deviation would have a big effect. Also, passage time and strength of the front in the day 2-3 period will impact the possibilities. Have to wait it out. But we wouldnt complain if we got a big one.

 

[Brandon Sullivan]

First major winter storm still looks to be on track for the 29-31. Kansas city first to pull the triggger and issue the winter stomr watch. Both surrounding offices are mentioning the same possibility. Latest HPC outlooks place a narrow band from MO-IL in the risk for .25 inches of ice accumulations. Also, HPC does have the area in the slight chance of snow>12 inches. Based on timing and models threat would most likely begin as significant ice accumulations, until precip can make the complete change over. Wouldnt be surprised to see new watches come out with this evenings shift or tommorow morning.

 

[Jim Bishop]

This looks like the first major winter storm of the season. I'd expect to see a good 6 inch swatch from Tulsa, Oklahoma northeast to Chicago, Illinois. The way the dynamics are setting up and the timing of the cold air it looks like the northern half of Illinois will see the greatest accumulations. I'd go for 8-12 inches in Chicago, but some isolated areas in northern Illinois, northeast Missouri and eastern Iowa will probably see well over 12 inches.

 

[Robert Dewey]

Latest 12Z NAM still has the system considerably eastward. This is in line with the previous SREF runs, and a "middle of the road" solution when compared to the GFS's no-show system. I'm thinking a SFC low will eventually track from AR to just east of CLE. The models should be getting a pretty good sample of the system now, and I expect the 12Z GFS to come back to its senses with a system probably similar to what the NAM is currently showing.

What I really like is the very tight baroclinic zone. The 850MB T's are in the -8C to -10C region within 50 miles of the front / 0C isotherm, so some pretty good snow growth should occur. I also suspect that snow ratios would be bumped up to 10:1 or 12:1 in those areas.

 

[rdale]

Note the incredible amount of spread on possible low-pressure centers Thursday night / Friday -- http://www.spc.noaa.gov/exper/sref/gifs/forecasts/SREF_Spaghetti_Low_Centers_f072.gif

GFS now taking it's more typical Appalachian route with the 12Z run, leaving MI dry (while NAM has 12-18" for the southeast quarter.) With such a spread, I still can't get excited about much happening around here...

 

[Robert Dewey]

Well, I'm going to stick with the NAM for now... The past three runs of the GFS have been absolutely horrible.

00Z - Farthest west with the system.
06Z - No system at all - open wave
12Z - Weaker system, much further east

The NAM has at least some continuity, but SREF is all over the place. With such a tight baroclinic zone, I can't help but think at least something will develop - whether it's a NAM or a GFS system remains to be seen.

 

[Brandon Sullivan]

I agree with rdewey. i think a sfc low should develop somewhere
along the front and move into the tn valley by 01/12z. warm
advection patterns ahead of the low would set up conditions
favorable for snow...freezing rain and/or sleet in the transition
zone from srn mo north into il...with a risk of lesser amounts of
snow extending up into the wrn great lakes. Agree with rdale too. Soo much spread in the models, its hard to stick my neck out. But do think it will be a big event somewhere

 

[Robert Dewey]

FWIW... The latest 12Z GGEM is pretty consistent with it's 00Z run. It also has an easterly track, completely bypassing everything from CLE westward... The 12Z run is just a *touch* deeper at 500MB, but otherwise it's very close to the previous run. The 12Z UKMET has a similar track to the NAM but is about 6 hours slower.

Not sure what's up with model continuity, but I would say odds are going against a strong winter storm right now.

 

[Danny Neal]

FWIW... The latest 12Z GGEM is pretty consistent with it's 00Z run. It also has an easterly track, completely bypassing everything from CLE westward... The 12Z run is just a *touch* deeper at 500MB, but otherwise it's very close to the previous run. The 12Z UKMET has a similar track to the NAM but is about 6 hours slower.

Not sure what's up with model continuity, but I would say odds are going against a strong winter storm right now.

which model proves to be most accurate normally??? like i said in another thread im new to all the models and im trying to learn so i was wondering what proves to be most accurate 9 times out of 10 if any?

 

[Robert Dewey]

which model proves to be most accurate normally??? like i said in another thread im new to all the models and im trying to learn so i was wondering what proves to be most accurate 9 times out of 10 if any?

That's the problem... There isn't one specific model that's more accurate than the other. Usually, you go with the "majority"... If 3 out of the 4 major models are showing a strong storm, then you can bet that there will be a strong storm (often middle of the road between the two extremes). However, when you have 4 models showing 4 different solutions with each run, it's pretty complicated.

As you can see from the link Rob Dale posted above, even the various runs of the same model (ensembles) aren't lining up.

 

[Brian Stertz]

probably can pull the plug on the ws watch for any wild winter wx in much of the Pleasant Hill CWA. It does look interesting in the I-44 corridor, but even that window is pretty short as progressive as things have changed up over the 00z runs last night.

 

[rdale]

probably can pull the plug on the ws watch for any wild winter wx in much of the Pleasant Hill CWA.

I think you may have jumped the gun going with a watch this early - in these preseason events, especially those with such a large variety of solutions, you should hold off until you're more certain.

Not saying your forecast is a bust yet ;> as we still have a few more runs...

 

[Danny Neal]

just watched the 1230 skilling forecast, he points out all the models except the "navy" one point the "major winter storm" as being a bust and if one does form it would pass south of chicago, still aways out but it went from being nothing to something and now back to nothing, looks like more of a severe weather event

 

[Robert Dewey]

just watched the 1230 skilling forecast, he points out all the models except the "navy" one point the "major winter storm" as being a bust and if one does form it would pass south of chicago, still aways out but it went from being nothing to something and now back to nothing, looks like more of a severe weather event

I think he means bust for his forecast area... The NAM certainly isn't a bust for the Great Lakes, and the GFS isn't a bust for areast further south and east.

 

[Danny Neal]

well thats what i meant im sorry i wasnt more specific on that, although he didnt use the words "major winter storm" anymore for anyone in the midwest, thats usually something he does is emphasize the fact that sometimes chicago "misses a major winter storm" hmmm....sorry for the confusion