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December 2022 Medium-Long Range Disco

WxUSAF

By WxUSAF,
in Mid Atlantic

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brooklynwx99
brooklynwx99

that system around the 23rd has been showing up on modeling for a while now, and it seems like the ensembles are beginning to parse the broad longwave features. with that said, there are actually a lo

brooklynwx99
brooklynwx99

EPS is absolutely gorgeous. this is primed for a high end snowfall event anywhere from BOS to RIC around the 15th through late month

WxUSAF
WxUSAF

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Paleocene

Paleocene

Posted
Posted

So I am a newb, and throwing one out there for any mets who care to respond, but whats up with the feature off baja california that exists in GFS (weak 500mb trough) but is totally nonexistent in the GEM? I was noticing that in the GFS the heights are way higher up the pacific coast towards alaska. For all I know this feature is irrelevant but just trying to learn what to look for, I'm following the discussion on the TPV above... 

gfs_z500a_us_30.png

gem_z500aNorm_us_31.png

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WxUSAF

WxUSAF

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3 minutes ago, WxUSAF said:
20 minutes ago, ORH_wxman said:

PV never makes it eastward on the GEM....the whole thing happens pretty early in the run....like look at 84h at H5 on GEM vs GFS....GFS already diving the PV lobe ESE with some ridging on the west coast while GEM has no ridging there and the PV is just going to park in W Canada with nothing to pin it under the NAO block.

 

FWIW, the NAM at 84h looks like the GFS and not the GEM.

Expand  

Visual.  Not surprisingly, GEFS looks a lot like the GFS.

 

gem_z500a_namer_15.png

gfs_z500a_namer_15.png

gfs-ens_z500a_namer_15.png

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BristowWx

BristowWx

Posted
Posted
1 minute ago, Eskimo Joe said:

Just cover the grass for Christmas. That's all I'm asking for.

of course like it or not this is the new bar being set for this event.  as things adjust lower the tension will get higher.  This is why we all need to get to the ABC store right away

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Maestrobjwa

Maestrobjwa

Posted
Posted

For those like me trying to visualize what you guys mean about that energy separating the TPV or not:

6 minutes ago, ORH_wxman said:

Well one of the sets of models will be wrong....so by deifnition one of them will change a lot. GFS and NAM are similar while GGEM/Ukie are in the other camp. You can see the PV diving SE on the GFS/NAM....here's a comparison between GFS and GEM at 84 hours....you can cleary see the GFS is already sending that piece of PV off to the east and southeast.

 

 

Dec16_12zGFSGGEMcompare.gif

 

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psuhoffman

psuhoffman

Posted
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45 minutes ago, mattie g said:

OK...so is that what I'm seeing happen on the Canadian?

 

33 minutes ago, WxUSAF said:

The lead shortwave that goes through the Lakes is pretty key obviously.  Want that strong, separated, and moving east to get trapped under the Baffin NAO ridge.  

 

28 minutes ago, Heisy said:


Yep. Take a look at newest CMC run and put it in motion and watch our tpv feature. It heads down the EPO ridge and then literally just stops in its tracks in the NW. Guess we’ll find out soon…

I was bored this morning and went back to see which model did better with the current ULL at day 6. GFS was way more accurate.


.

It actually diverges by hr 54, believe it or not.  The key seems to be the strength of the first SW that amplified around the TPV in western Canada. Both camps do a fujiwara dance between several features rotating around that TPV. But on the Icon/CMC/Euro/Ukmet the initial amplification around 54 hours is much stronger and the whole thing remains consolidated and just kinda spins in place. That means when the next piece of energy comes in (what becomes the storm) everything is anchored in western Canada and it dives in way too far west. 
 

The GFS and some previous runs of the euro and Cmc were weaker with the initial amplification in western Canada.  That seems to allow the TPV to be impacted by the flow under the stronger vortex to the north and slide east, not remain anchored. 
 

It seems it simply comes down to how strongly the vortex that drops into south western Canada in about 48 hours is. Too strong and it resists the flow, gets stuck and the next lobe dives into the west. Weaker and it slides east and sets up a possible eastern storm. 

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Heisy

Heisy

Posted
Posted
It actually diverges by hr 54, believe it or not.  The key seems to be the strength of the first SW that amplified around the TPV in western Canada. Both camps do a fujiwara dance between several features rotating around that TPV. But on the Icon/CMC/Euro/Ukmet the initial amplification around 54 hours is much stronger and the whole thing remains consolidated and just kinda spins in place. That means when the next piece of energy comes in (what becomes the storm) everything is anchored in western Canada and it dives in way too far west. 
 
The GFS and some previous runs of the euro and Cmc were weaker with the initial amplification in western Canada.  That seems to allow the TPV to be impacted by the flow under the stronger vortex to the north and slide east, not remain anchored. 
 
It seems it simply comes down to how strongly the vortex that drops into south western Canada in about 48 hours is. Too strong and it resists the flow, gets stuck and the next lobe dives into the west. Weaker and it slides east and sets up a possible eastern storm. 

This is an awesome post.

Will be fun to see which one caves.

My opinion based on watching model wars play out over 20+ years…

If GFS does cave don’t expect a step down trend. It will go from what it just showed today at 12z to a full on cutter in one run because of how important this feature is.

Get me 2 more runs, 18 & 00z with similar TPV handling and I’ll jump on board with GFS


.
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Chris78

Chris78

Posted
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4 minutes ago, nj2va said:

I feel like the UK used to be a better model but the last few years has been a trainwreck for events I can remember.  And don't get me started on the ICON.  Two models IDGAF what they show.

Uk is probably a little better than the Icon. Which isn't saying much. Only reason anyone looks at the icon is because it's available on TT.

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Bob Chill

Bob Chill

Posted
Posted
7 minutes ago, nj2va said:

I feel like the UK used to be a better model but the last few years has been a trainwreck for events I can remember.  And don't get me started on the ICON.  Two models IDGAF what they show.

The ukie only gets attention when it shows snow in the face of everything else. Otherwise, imho, it usually adds confusion and uncertainty instead clearing up gfs/euro divergence. I keep it simple in mid to short range. Euro/gfs blend, hedging towards which one makes the most sense (subjective). Nams are good t add 48 hours in for clearing up qpf/temp details when things are dicey. There are magnitudes more old threads with post storm discussion that says euro/gfs blend was good from 4 days out or whatever. Rarely if ever does the cmc or ukie end up being the best mid range solution. ICON should be ctrl-alt-deleted

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mattie g

mattie g

Posted
Posted
39 minutes ago, H2O said:

I don't really care for a massive jacked storm cause this is always a concern IMBY.  

image.thumb.png.8df81832bef9d5f972adfa378bbf836c.png

It would be really annoying to flip for a little bit, but I think this run would be just that - a super quick flip before temps crash as the CCB cranks.

Same panel for me has me at 33F at the surface, so I might *just* be snow, but either way that flip would be frustrating but not make too terribly much difference in the end.

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IUsedToHateCold

IUsedToHateCold

Posted
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1 minute ago, mattie g said:

It would be really annoying to flip for a little bit, but I think this run would be just that - a super quick flip before temps crash as the CCB cranks.

Same panel for me has me at 33F at the surface, so I might *just* be snow, but either way that flip would be frustrating but not make too terribly much difference in the end.

We flip or dry slot down here in the swamps for all the big ones. No biggie, we still get 1-2 feet from a storm like this. 

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87storms

87storms

Posted
Posted
1 minute ago, Bob Chill said:

From what I see, the gefs lost a # of deep western solutions run over run. Could be follow the leader bug good news either way. However, there was also a less than small shift north with the heaviest precip. My guess is there are prob more misses with late cyclogenesis 

A late developing Miller B seems like the biggest risk at this point, at least to this hobbyist.  I've always been of the mindset that we do precip pretty well here, so get the cold first and roll the dice on a wave.

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