December 21st-23rd Winter Storm

[IWXwx]

[IllinoisWedges]

12z GFS 

[Snowstorms]

The GFS and CMC are worlds apart and is clearly evident on the vort maps, lol. 

In turn, the GFS completely decimates the risk of any "Christmas storm". 

[HillsdaleMIWeather]

12Z GFS is another step in the right direction 

[Snowstorms]

Wow @ 12z CMC!! Hard to make a firm conclusion on what to expect starting this Friday and beyond given the high model variability. Hopefully we get a clearer picture by tonights 00z runs as we get better sampling. 

[Frog Town]

15 minutes ago, Snowstorms said:

Wow @ 12z CMC!! Hard to make a firm conclusion on what to expect starting this Friday and beyond given the high model variability. Hopefully we get a clearer picture by tonights 00z runs as we get better sampling. 

My thoughts exactly!  How often does the CMC verify more than 4 days out, is the big question.  

[RCNYILWX]

Despite the large difference in surface low track and also timing on the GFS and GGEM, they both went strongly toward the general idea portrayed by the 00z Euro suite of a stronger southern stream system (which ironically the GEM was the first to show a few days ago). The GGEM hangs it back more and is therefore slower and tracks farther southeast.

 

Ideally for my coverage area (northern IL and northwest IN) the wave would strengthen even quicker to consolidate and deepen the 850 mb low quicker. Using the 12z GFS and 00z Euro as a reference, the poor antecedent air mass messes things up for us despite a climatologically favorable surface low track.

 

But we can get this improved (assuming a still favorable sfc low track) by an earlier maturing and tucked in 850 mb low, which will surge the cold enough air in quicker northwest of the sfc low. You can see that the 850 mb low starts out very broad even as sfc low is deepening rapidly at 06z Saturday but then becomes more more consolidated 6 hours later over MI. To get this outcome, we'd want to see a trend toward an even stronger wave that would deepen the whole system quicker while not cutting too far west.

 

 

 

 

 

 

[Jim Martin]

Early Christimas Eve morning off this morning's Canadian forecast model run.

[hawkeye_wx]

The 12z UK doesn't do a lot with the southern system.

[UMB WX]

Chicago is due and Detroit is a snow magnet. I don't have high hope for the new worst climo, MKE.

At least part one is turning pretty meh  ATM which in return seems to get some excitement going on the GFS closer to the GL'S instead of saying congrats Canada mostly

[RCNYILWX]

The 12z UK doesn't do a lot with the southern system.

It doesn't deepen it as much as GFS and Euro but still appears to be a shift from 00z run looking at the available 24 hour panels at this range. 1005 mb low over Lake Erie 12z Saturday. The lack of any data other than the surface makes it hard to discern the trends.

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[josh_4184]

12Z GFS crushes Northern Mi

[UMB WX]

^ 0 for MKE - lock it in

[Jonger]

This is soooo sexy for northern Michigan snowhounds like myself. I just fear it moving north more.

The fact that it's so strong leads me to believe that the only thing that can happen is weakening.

 

[Hoosier]

3 hours ago, RCNYILWX said:

Nice writeup there. Hoping for positive trends on the modeling today. The 06z operational GFS made a step toward the 00z Euro, with several 06z GEFS members also jumping more substantially toward a Euro/EPS like solution. Hoosier, are we allowed to post the EPS ensemble low position graphics on here?

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Go ahead.  I'm curious.

[Hoosier]

Doing a dprog/dt on the GFS, pretty remarkable shift over the last couple runs.  

NAM at 84 hours (yeah I know) doesn't look that close to the GFS/GEM.

[UMB WX]

3 minutes ago, Jonger said:

This is soooo sexy for northern Michigan snowhounds like myself. I just fear it moving north more.

The fact that it's so strong leads me to believe that the only thing that can happen is weakening.

 

It's spooky how far taint could get.  I can deal with a miss to the south....that's the rule here the past few winters.  A miss to the north/W would irk me much more. 

[RCNYILWX]

Go ahead.  I'm curious.

Valid time 06z Saturday 12/23
1st image: 00z 12/19 EPS
2nd image: 12z 12/18 EPS

Considering the trends in the modeling already today after the jump on 00z Euro, including 12z GEFS, I'm inclined to believe the trend is real with this, but we'll see what 12z Euro suite shows. The parent wave coming ashore on the Pacific coast was partially sampled by RAOBs for 12z run and should be fully sampled for 00z cycle.

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[ams30721us]

22 minutes ago, RCNYILWX said:

Valid time 06z Saturday 12/23
1st image: 00z 12/19 EPS
2nd image: 12z 12/18 EPS

Considering the trends in the modeling already today after the jump on 00z Euro, including 12z GEFS, I'm inclined to believe the trend is real with this, but we'll see what 12z Euro suite shows. The parent wave coming ashore on the Pacific coast was partially sampled by RAOBs for 12z run and should be fully sampled for 00z cycle.

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WSI Exp. Thunder model is very similar to the 12z GFS  with the two wave (stronger 2nd wave) idea...

[Hoosier]

3 minutes ago, ams30721us said:

WSI Exp. Thunder model is very similar to the 12z GFS  with the two wave (stronger 2nd wave) idea...

I've heard good things about that Deep Thunder model but don't know much about it.  Does it seem fairly reliable?

[hlcater]

That WSI run appears it's keeping more of the north(initial) wave around, which would have implications; likely affecting how hard it cuts. The less of the initial system there is, I feel like the harder this storm will cut because the second wave would end up being stronger in such a case as less energy is "spent"/ejected with the initial wave.

[Hoosier]

12z Euro is slower than the GFS, but it looks like it's about to start deepening fairly quickly by 96 hours.

[Hoosier]

Euro is just a bit too slow to really crank it.  Lack of cold air keeps snow amounts minimal with the southern wave.

[Hoosier]

There may be a way for the Euro type solution to work, but it would perhaps need to slow down some a la GEM.  If you notice the GEM, it doesn't really deepen the surface low much but there's enough cold air on the northern side for some good snow.

[Thundersnow12]

3 minutes ago, Hoosier said:

Euro is just a bit too slow to really crank it.  Lack of cold air keeps snow amounts minimal with the southern wave.

It took a nice step to a less sheared wave ejecting into the plains and then dampens it quickly.

Also looks to be suffering from some convective feedback looking at SLP locations compared to s/w locations.  

[Tarheel17]

1 hour ago, Hoosier said:

Doing a dprog/dt on the GFS, pretty remarkable shift over the last couple runs.  

NAM at 84 hours (yeah I know) doesn't look that close to the GFS/GEM.

*I am visiting family in SE MI hence I am posting here*

I think it is worth keeping an eye on the NAM. I know it has a bad rap and often goes very over-amped on systems, but following the SE boards it's had two cases recently where it was much better than the global models.

1) Sniffing out a warm nose in a strong synoptic setup. This is very prevalent in the SE from Atlantic/GOM air. Last January the NAM sniffed out a warm nose 3 days out that the EURO/GFS/GEM all missed, even with the event right on top of us.

2) Marginal temperature/precipitation event along a frontal passage. The NAM and other short range, meso-scale models predicted the precipitation field and temperature viability 3 days in advance  during our Dec 8 event as cold air pushed over the mountains. The globals completely missed a relatively narrow band of 8-12 inches of snow in that environment.

I am not saying to trust the NAM by any means, but it has shown enough recently in the SE to at least merit observation and consideration, even in the ~3 day range. Not sure if it was upgraded or what.

 

[Hoosier]

17 minutes ago, Tarheel17 said:

*I am visiting family in SE MI hence I am posting here*

I think it is worth keeping an eye on the NAM. I know it has a bad rap and often goes very over-amped on systems, but following the SE boards it's had two cases recently where it was much better than the global models.

1) Sniffing out a warm nose in a strong synoptic setup. This is very prevalent in the SE from Atlantic/GOM air. Last January the NAM sniffed out a warm nose 3 days out that the EURO/GFS/GEM all missed, even with the event right on top of us.

2) Marginal temperature/precipitation event along a frontal passage. The NAM and other short range, meso-scale models predicted the precipitation field and temperature viability 3 days in advance  during our Dec 8 event as cold air pushed over the mountains. The globals completely missed a relatively narrow band of 8-12 inches of snow in that environment.

I am not saying to trust the NAM by any means, but it has shown enough recently in the SE to at least merit observation and consideration, even in the ~3 day range. Not sure if it was upgraded or what.

 

NAM scores every so often... the problem is that you never really know when it will be lol.  Seriously though, it does have some uses... one of the things I like it for is the situations when mesoscale banding is a significant player.

[Hoosier]

18z NAM is a tad colder and hinting at some freezing rain in northern IL.  The globals have been slower to break out precip there.

[Hoosier]

18z NAM should come north with the southern system.  Wave looks sharper at 60 hours.

[jlauderdal]

1 hour ago, Tarheel17 said:

*I am visiting family in SE MI hence I am posting here*

I think it is worth keeping an eye on the NAM. I know it has a bad rap and often goes very over-amped on systems, but following the SE boards it's had two cases recently where it was much better than the global models.

1) Sniffing out a warm nose in a strong synoptic setup. This is very prevalent in the SE from Atlantic/GOM air. Last January the NAM sniffed out a warm nose 3 days out that the EURO/GFS/GEM all missed, even with the event right on top of us.

2) Marginal temperature/precipitation event along a frontal passage. The NAM and other short range, meso-scale models predicted the precipitation field and temperature viability 3 days in advance  during our Dec 8 event as cold air pushed over the mountains. The globals completely missed a relatively narrow band of 8-12 inches of snow in that environment.

I am not saying to trust the NAM by any means, but it has shown enough recently in the SE to at least merit observation and consideration, even in the ~3 day range. Not sure if it was upgraded or what.

 

im visiting from south florida, will be in chicago and was looking for a snowstorm, maybe end of next week..oh well