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Winter 2024/2025 December Thread


AMZ8990
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56 minutes ago, Carvers Gap said:

American LR extended modeling is much warmer than Euro/Canadian products of similar time ranges.  I wonder if something has been tweaked or updated in with that model.  It is missing cold fronts that it didn't use to....

Agree. Started to mention that yesterday while looking at the GFS snowfall projected output. I noticed clearly the Data from the flawed Pennington gap Station is very evident. It could be just an over time thing but, seemed a bit more of sudden prominence on the layout. At any rate, it looks less smoothed and more micro detailed so, apparently something has been done. Will see what I can find. 

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4 hours ago, Daniel Boone said:

Agree. Started to mention that yesterday while looking at the GFS snowfall projected output. I noticed clearly the Data from the flawed Pennington gap Station is very evident. It could be just an over time thing but, seemed a bit more of sudden prominence on the layout. At any rate, it looks less smoothed and more micro detailed so, apparently something has been done. Will see what I can find. 

Looks like 12z (operational) is more realistic.  But the entire American model suite GFS/CFS is way out of step.  It might be right, but it looks crazy wonky.  I do agree there are times NA is scoured and no cold air remains.  The last time we saw that happen was when the GOA low parked itself off the coast of southern Alaska, and flooded Canada with maritime air.  I don't think American modeling is right, but it certainly could be...I just don't think it is.

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14 minutes ago, John1122 said:

The 12z AI Euro was a major winter storm from Nashville west as a storm ran the Apps. 

Actually, if there's enough amp and forcing from the ph 6 MJO, that would be a viable solution with the Trough probably centered from the Rockies to the Apps. East of typical Ph 6 due to the Eastward forced Pacific State.

Some say that east based Nina's can result in an Eastern Trough with a ph 6 MJO. I couldn't find many studies of significance irt that however.

  Blocking is showing in some model's now in Tandem with a tall PNA Ridge in the long Range. If that were to be the Case that System would probably be a Slider and we'd all get hit.

 

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16 minutes ago, Daniel Boone said:

Actually, if there's enough amp and forcing from the ph 6 MJO, that would be a viable solution with the Trough probably centered from the Rockies to the Apps. East of typical Ph 6 due to the Eastward forced Pacific State.

Some say that east based Nina's can result in an Eastern Trough with a ph 6 MJO. I couldn't find many studies of significance irt that however.

  Blocking is showing in some model's now in Tandem with a tall PNA Ridge in the long Range. If that were to be the Case that System would probably be a Slider and we'd all get hit.

 

18z is an E TN / DC special.  Decent signal for a storm east of the MS.

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53 minutes ago, Carvers Gap said:

18z is an E TN / DC special.  Decent signal for a storm east of the MS.

Yeah, very possible too. weak ph 6 with +TNH . IF PH 6 is near COD like Euro shows, probably the Eastward solution imo. Many Mets are banking on typical run of the mill ph 6 mild end of December. Some even scoffing at the cold runs and those that believe otherwise. 

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The Canadian (which was excellent for this morning's event) had a similar path to the Euro AI model that had an East Coast storm. Pretty classic path for much more of East Tennessee to see snow than was depicted by the model.  Crashing cold and a low that tracks over interior SC and NC a good 90 miles or so from the coast.  GFS is progressive and just sweeps everything out. Something it's been doing a lot of early as winter is starting, before playing catch up late. 

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Maybe what interests me most is an active northern stream which would bring potential upslope snows and clippers into the area between December 20-25th.  Looks like the southern branch might also be active, but with less certainty - if one can have any certainty at this range.  If this look persists, the chances for at less a minor snowfall increase greatly for at least someone in the forum area to have snow on the ground by Christmas Eve.  Travel headache potential would be significant if that persists.

....The Euro AIFS probably gets credit for sniffing out the post Dec 20 cold shot.

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I think American modeling is over-doing the chinook that looks likely just after Christmas.  The Euro AIFS and Weeklies control(from yesterday) both have that chinook ending fairly quickly, and only have chinook air flooding the continent for a brief amount of time.  The 6z AI has the next cold shot plowing right through it.  Again, American modeling is much warmer than any other modeling.  To me, the algorithm looks like it has been changed for the model.  It is almost completely bling to cold fronts outside of ten days....they ensemble is worse.  Anyone have the link to how modeling is scoring?

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2 hours ago, Carvers Gap said:

I think American modeling is over-doing the chinook that looks likely just after Christmas.  The Euro AIFS and Weeklies control(from yesterday) both have that chinook ending fairly quickly, and only have chinook air flooding the continent for a brief amount of time.  The 6z AI has the next cold shot plowing right through it.  Again, American modeling is much warmer than any other modeling.  To me, the algorithm looks like it has been changed for the model.  It is almost completely bling to cold fronts outside of ten days....they ensemble is worse.  Anyone have the link to how modeling is scoring?

All I could find is what looks like was done back in September and that was to GFS MOS Output.

https://www.nco.ncep.noaa.gov/pmb/changes/

Only changes to GFS itself were June ' 21.  So, don't know the problem unless not let out to the public . I'll see if KMRX knows anything.

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1050+ HP coming down the Plains has been a good setup lately for this forum.  The 12z GFS has 2 potential winter storms inside of 9 days.  The EURO AIFS has been hinting at this 1-2 punch for a few days...maybe 1-2-3.   Cold supply and storms appear to be in the system.  We just need them in the same place at the same time.

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The interesting thing about recent Nina patterns, they have kind produced these one-off storms.  Then, we are done.  This pattern is a nickel and dime one.  That adds up over time.  We got more snow in my neighborhood last night.  I have nearly lost count of the number of light dustings we have had so far.  That is pretty rare in my local for December 12th!   It has also been really windy of late which implies variability in the weather pattern.  Variability might be what works in this day and age - the deck gets reshuffled almost weekly.  Cold patterns don't hit and hold...so maybe small doses are better???  Either way, no complaints from me on what the GFS has been cooking up inside of d10 for several runs now.

I just don't want what it is cooking after Christmas!!!!

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These setups with 2 systems back to back always get confusing to follow along with.  Can't look at the 22nd until the 19th is set.  Gfs pushes the 19th trough so far east the later event is suppressed OTS and shredded.  That's actually a pretty common evolution of this pattern. Seen it many times.

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I am just watching this big hp around the 21-22nd.  If it stays at that strength, I would be really surprised if some in the forum area don't see at least minor accumulations of snow w/ either a slider, clipper, and/or inland runner.  We live in the Upper South, so there plenty of ways to miss...but that is a good setup.  

Looks like maybe a warm-up after that, but the warm-up has been getting pushed back quite a bit.  I do think a western chinook is on tap and spread eastward.  Looks like maybe cold returns after the first week of January...and that might be true winter at that point.

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He's been making some good vids as of late compared to some of his in the past.

Right now the SPV the last few days has been just  displaced and tilted.But there is as least some some signs by the Euro it could change in upcoming days.But right now its fairly like a rock.Going into 2014 the SPV was weak and let cold air pour into NA

2014 i think it was Daniel and i was talking about that year several days ago with the record proportion +TNH and +EA in 2014,excuse me if i got that poster wrong,i'm to lazy to go back and look.

But that winter in Jan., 2014 it got extremely cold into even parts of Ky dropping down into the -30s.

But 2013-2014 winter does have some similarity going for it compared to this winter.Even if you look at the ONI both these winters into S-O-N were both -0.2,if we we get a repeat of 2014,who knows ATM,we know how things can change in our parts

Tropical-Monitoring-North-Carolina-Institute-for-Climate-Studies-12-13-2024_11_06_AM.png

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9 hours ago, jaxjagman said:

He's been making some good vids as of late compared to some of his in the past.

Right now the SPV the last few days has been just  displaced and tilted.But there is as least some some signs by the Euro it could change in upcoming days.But right now its fairly like a rock.Going into 2014 the SPV was weak and let cold air pour into NA

2014 i think it was Daniel and i was talking about that year several days ago with the record proportion +TNH and +EA in 2014,excuse me if i got that poster wrong,i'm to lazy to go back and look.

But that winter in Jan., 2014 it got extremely cold into even parts of Ky dropping down into the -30s.

But 2013-2014 winter does have some similarity going for it compared to this winter.Even if you look at the ONI both these winters into S-O-N were both -0.2,if we we get a repeat of 2014,who knows ATM,we know how things can change in our parts

Tropical-Monitoring-North-Carolina-Institute-for-Climate-Studies-12-13-2024_11_06_AM.png

Seemingly what the Euro is showing today is the PV is headed towards the Baffin Sea but it still looks like a brick but either way,no reason to nicpick right now,see what it shows in a couple days or so,ill move this into winter thread,no need to keep it into Dec

Modal-view-of-atmospheric-circulation-Modes-12-13-2024_09_06_PM.png

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27 minutes ago, Daniel Boone said:

0Z GFS is a slap in the face for any hopes of a white Christmas . Terrible run compared to recent one's. Totally breaks down PNA Ridge. Looks like it's showing effects of MJO . 

That's my thinking also but it might not be t-shirt weather...lol..but if you want snow better go up north,not promising for us

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