December 2011 General Discussion/Obs

[Chicago Storm]

Might as well get this going.

What will December bring... or ?

[michsnowfreak]

Ahh, "December". What a lovely word!

[SpartyOn]

Another month closer to severe and death ridges. Enjoy it as it flies by. Ready for a blizzard! Bring it on.

[snowstormcanuck]

Well, I will see some accumulating snow this month. Climo guarantees it. For that, I am grateful. That being said, if mother nature could do her best to fashion this December in the mould of a December 2000 or 2008, I would escalate my gratefulness tenfold.

[Chicago WX]

December 2011

Average temp: 33.5º (+3.0º)

Precipitation: 4.50" (+1.99")

Snowfall: 5.0"

Can't say I hate this forecast right now, from my winter stab in the dark for LAF.

[Guru Of Reason]

Lock this in!!!

[Thunder Road]

Looking pretty far out, 12z GFS and Euro seem to support a slight LES threat for northern Indiana for next Friday.

The lake is running about 8-9 C right now, so if we guess it'll be around 7-8 C next Friday, with h85 temps of -8 to -10 C, that's a pretty healthy delta T.

Looking specifically at the GFS BUKFIT for KGYY, sfc-850mb shear is less than 40 degrees most of the time and the winds in that layer max out at 22 knots (which is a little bit high...I think...but still low enough for some banding formation).

12z GFS raw data spits out 0.10" for GYY and VPZ, and the Euro was showing a bit more, generally 0.15-0.175" with a spot over GYY of >0.175". Although I've never paid close attention to LES events before having never lived in a LES zone until now....do the synoptic models handle QPF well, or if the conditions are right, should I just assume there will be more precip than modeled?

Feel free to correct me on this stuff, I'm really just practicing looking at LES conditions since it's new to me.

[Hoosier]

12z GFS raw data spits out 0.10" for GYY and VPZ, and the Euro was showing a bit more, generally 0.15-0.175" with a spot over GYY of >0.175". Although I've never paid close attention to LES events before having never lived in a LES zone until now....do the synoptic models handle QPF well, or if the conditions are right, should I just assume there will be more precip than modeled?

You absolutely do not want to use the QPF on the low-res models to make a forecast...that being said, if they are spitting out decent amounts then you know it's probably going to be a big event. Hi-res models are a better choice for banding location and qpf although they do tend to be a bit too wet at times in my experience.

[Thunder Road]

You absolutely do not want to use the QPF on the low-res models to make a forecast...that being said, if they are spitting out decent amounts then you know it's probably going to be a big event. Hi-res models are a better choice for banding location and qpf although they do tend to be a bit too wet at times in my experience.

Ok thanks.

What would you consider decent?

[Hoosier]

Ok thanks.

What would you consider decent?

Anything more than a quarter inch QPF on a global/lower resolution model is what I'd call significant. Anything over a half inch usually means it's going to be pretty big. That is just a general guideline I use since the hi-res models typically don't go out past 48 hours.

[Thundersnow12]

You absolutely do not want to use the QPF on the low-res models to make a forecast...that being said, if they are spitting out decent amounts then you know it's probably going to be a big event. Hi-res models are a better choice for banding location and qpf although they do tend to be a bit too wet at times in my experience.

Or trying to do it a week away..

[Thunder Road]

Or trying to do it a week away..

Haha true. I just happened to notice that and I wanted to test out the knowledge I got from the MetEd module on LES.

[Thundersnow12]

Haha true. I just happened to notice that and I wanted to test out the knowledge I got from the MetEd module on LES.

those are good, very informative.

[Trent]

You absolutely do not want to use the QPF on the low-res models to make a forecast...that being said, if they are spitting out decent amounts then you know it's probably going to be a big event. Hi-res models are a better choice for banding location and qpf although they do tend to be a bit too wet at times in my experience.

I've also found that the WRFs tend to always overdo the QPF. The banding placement tends to be somewhat accurate, but on a more macro scale. From the NCEP models, I've generally found that the NMM to have more QPF and be more localized, while the ARW generally has a more south and west bias to band placement, with generally lighter QPF and broader bands.

[snowstormcanuck]

The STJ looks pretty anemic on all runs of the GFS the last several days. Even if we do transition into a colder period, it seems difficult to foresee a lot of snowstorm potential (at least not within the first 1-2 weeks of December).

[cyclone77]

The operational GFS has been advertising a storm next weekend on the last several runs. Also, the 12z and new 00z shows things getting active starting around the 10th. Way out in time, but you get the feeling that things will eventually begin to get active as we get deeper into December.

[Organizing Low]

The STJ looks pretty anemic on all runs of the GFS the last several days. Even if we do transition into a colder period, it seems difficult to foresee a lot of snowstorm potential (at least not within the first 1-2 weeks of December).

good point

hopefully something pops us like it usually does, because the pattern is not bad at all as we move forward...but it is odd to see all the models consistently and unanimously pointing to a relatively quiet period, usually there is one with a fantasy storm

[daddylonglegs]

Gfs looks very dry around here through first 10 days of December. Still wouldn't get too excited.

[snowstormcanuck]

Kinda sucks that the models seem to be in agreement that the s/w coming in to the BC coast on D3 ends up retrograding to Baja. We have that nice low level baroclinic zone setting up across the mid MS valley around D5 that would be a prime path for a winter storm.

[cyclone77]

The GFS/GEM throw a bone to those of us to the west that are missing the big storm Tuesday/Wednesday. Shows a decent little wave moving across WI/IL late Thursday with some light snow. Better than nothing lol.

[snowstormcanuck]

Through 240, the 12z EURO looks much cooler than its past couple of runs. But like the GFS, it's northern stream dominant. No storm potential to speak of.

[toronto blizzard]

Through 240, the 12z EURO looks much cooler than its past couple of runs. But like the GFS, it's northern stream dominant. No storm potential to speak of.

I wouldn't necessarily say that. Looking at 192 there appears to be some type of frontal boundary setting up like you said which would promote an overrunning potential plus you have to consider it's bias of leaving too much energy in the SW.

[snowstormcanuck]

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I wouldn't necessarily say that. Looking at 192 there appears to be some type of frontal boundary setting up like you said which would promote an overrunning potential plus you have to consider it's bias of leaving too much energy in the SW.

But if you check 216, the front is off the EC. The whole pattern is composed of progressive northern stream s/ws. Not really conducive for hefty overrunning snows. i'll give you the EURO bias of leaving too much energy in the SW, but the GGEM and GFS seem to agree, which increases the probabilities that the depiction is not in error.

It's not impossible that something will pop up, but this isn't like Dec 2008 where the parade of storms was well advertised by the models 10 days in advance.

[Chicago WX]

I actually think the upcoming pattern can produce nicely. Maybe not a "huge" storm in there, but there's enough energy in the SW along with cold enough air to get some moderate storms. I'm not sure that any one single run is going to pin point it at this stage. But I also think the farther north you are, the better (i.e. I-80 north). At least it's not a complete torch or numbing cold/dry look.

[toronto blizzard]

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But if you check 216, the front is off the EC. The whole pattern is composed of progressive northern stream s/ws. Not really conducive for hefty overrunning snows. i'll give you the EURO bias of leaving too much energy in the SW, but the GGEM and GFS seem to agree, which increasesthe probabilities that the depiction is not in error

Ya but the GGEM did have a pretty decent wave as did the nogaps. Anyway you look at it should be a interesting week watching the models. Ahh it's that time of the year again.

It's not impossible that something will pop up, but this isn't like Dec 2008 where the parade of storms was well advertised by the models 10 days in advance.

[toronto blizzard]

To SSC just read the second paragraph I wrote. I messed up when I was writing

[Snowstorms]

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But if you check 216, the front is off the EC. The whole pattern is composed of progressive northern stream s/ws. Not really conducive for hefty overrunning snows. i'll give you the EURO bias of leaving too much energy in the SW, but the GGEM and GFS seem to agree, which increases the probabilities that the depiction is not in error.

It's not impossible that something will pop up, but this isn't like Dec 2008 where the parade of storms was well advertised by the models 10 days in advance.

It has similarities to Dec 2007/1975. Dec 2007 was quite dry generally speaking with only two snowstorms. One beast around Dec 16ish which dropped 30-40cm or 12-16" in my area while somehow YYZ only recorded 20cm.

The jet stream is too zonal for any big storms to form atleast thru the next 7-10 days but If we can develop a weak trough perhaps that can change but lets see how the S/W energy develops. Certainly the Euro is alot cooler than the GFS in December. There's the possibility for some kind of storm to develop between Dec 5 and 10 IMO.

[snowstormcanuck]

It has similarities to Dec 2007/1975. Dec 2007 was quite dry generally speaking with only two snowstorms. One beast around Dec 16ish which dropped 30-40cm or 12-16" in my area while somehow YYZ only recorded 20cm.

No debate Pearson sucks at measuring snow. But in that case I can verify that it was close. I had only 22cm (9") here in central Etobicoke. I know downtown picked up 30-35cm (12-14") due to lake enhancement on Saturday the 15th. You must have got into some type of meso-band up there in Vaughan.

[wisconsinwx]

Can someone elaborate on how Twisterdata's snowfall map is created? I keep looking at how Thursday night's light snow will accumulate, and I see this continual bubble over the SE corner of WI (Milwaukee, Racine, and Kenosha); this bubble is not even over Chicago, which if anything should be the location that would see a mix or rain from the minor disturbance. Are we more of a snow bubble than anywhere, or is Twisterdata just kinda weird?

[Chicago WX]

Can someone elaborate on how Twisterdata's snowfall map is created? I keep looking at how Thursday night's light snow will accumulate, and I see this continual bubble over the SE corner of WI (Milwaukee, Racine, and Kenosha); this bubble is not even over Chicago, which if anything should be the location that would see a mix or rain from the minor disturbance. Are we more of a snow bubble than anywhere, or is Twisterdata just kinda weird?

Snow bubble, seriously? I wouldn't concern yourself with any clown map, be it Twisterdata or Earl Barker, etc.