Winter 2024/2025 December Thread

[AMZ8990]

Let the speculation begin!  

[Carvers Gap]

Saddle up!  Here we go!!!  The Weeklies ext(Euro) have the Christmas warm-up, but then they move back to seasonal which is plenty good during early January.  I lean warm for winter overall with a cold start.  That said, the weaker this ENSO gets....the more we are dealing with an SST forecasting bust which is in progress.  If this goes Nada...probably still warm.  But....... a weak La Nina has to be accounted for in terms of cold intrusions.  It also brings a new set of analogs into play if one uses analogs.  I guess what I am saying is that my original forecast is probably busted right now as we speak.  If it was Monopoly, I would say, "Bank error in your favor.  Go collect $200."  This first cold shot could be a one-off.  That has certainly been the case for the last few Nina winters....cold until Christmas and then torch.  However, in middle and western areas of the forum, winter returned during a couple of winters to historic levels.  

What I like looking at LR forecasting:

-Sometimes we can't get it to snow at all when the cold comes around.  In LR modeling, snow is accompanying the cold at varying latitudes east of the MS.

-The late landfalling hurricanes do have some correlation to wild winters here. 

-We haven't had any early season snowfalls...seems to be the kiss of death for bad winters IMBY.

-There is cold in North America.\

-I tend to think the EPO is going to be the driver through the first half of winter w/ warm (maybe very warm) interludes.  I did NOT think that several weeks ago.  However, I think winter is showing a bit of its hand.  

-If I was going to re-write my winter forecast, it would be similar.  HOWEVER, I think winter returns during January.  

-I have been super uneasy(and have stated that) about this winter.  We may struggle to get to La Nina status.  Why is that important here?  The SER will have trouble holding all winter IMHO.  A moderate or strong La Nina?  Get out the Bermuda shorts and don't put away the lawn mower.  A weak La Nina?  Wicked cold to the Apps and beyond w/ maybe even some Piedmont ice/snow.  

-Bottom line....climatology for weak La Ninas in this area is IMHO the best, single predictor of cold winters here.  I will take that ENSO state over all others.  And that gives me great, great pause.  I still lean warm for winter, but Mother Nature could yank that carpet out at any time.

What I don't like:

PDO

MJO tendencies towards warm phases(but this winter could be one of those that bucks the trend....if my suspicion about the EPO as the driver is correct....the EPO trumps the entire pattern)

The cold is just a bit early.  I like cold to show up just before or after Christmas.

Analog in play:

95-96....Cold came in waves, and snow moved along that boundary at times during the winter.  

Today's 8-14 analogs:

John and Boone can fish the info out of these.  I think there are some decent ones in there...

19891217
19561202
19511211
19551214
19761203
20081205
19631213
19611210
19641121
20001207

One last note:  

The ingredients are there for an early season snowstorm, and maybe more than one.  No guarantees, but that is wild given how warm it has been.

[fountainguy97]

06z Hrrr has a nice slug of moisture swinging down. This is more than just NW flow. And could give some areas outside the typical regions some snow.

 

[Daniel Boone]

2 hours ago, fountainguy97 said:

06z Hrrr has a nice slug of moisture swinging down. This is more than just NW flow. And could give some areas outside the typical regions some snow.

 

Yeah, as you said, that's not NWF Snow. Really doesn't look like much if any LE will get involved. 

[Daniel Boone]

16 hours ago, Carvers Gap said:

Saddle up!  Here we go!!!  The Weeklies ext(Euro) have the Christmas warm-up, but then they move back to seasonal which is plenty good during early January.  I lean warm for winter overall with a cold start.  That said, the weaker this ENSO gets....the more we are dealing with an SST forecasting bust which is in progress.  If this goes Nada...probably still warm.  But....... a weak La Nina has to be accounted for in terms of cold intrusions.  It also brings a new set of analogs into play if one uses analogs.  I guess what I am saying is that my original forecast is probably busted right now as we speak.  If it was Monopoly, I would say, "Bank error in your favor.  Go collect $200."  This first cold shot could be a one-off.  That has certainly been the case for the last few Nina winters....cold until Christmas and then torch.  However, in middle and western areas of the forum, winter returned during a couple of winters to historic levels.  

What I like looking at LR forecasting:

-Sometimes we can't get it to snow at all when the cold comes around.  In LR modeling, snow is accompanying the cold at varying latitudes east of the MS.

-The late landfalling hurricanes do have some correlation to wild winters here. 

-We haven't had any early season snowfalls...seems to be the kiss of death for bad winters IMBY.

-There is cold in North America.\

-I tend to think the EPO is going to be the driver through the first half of winter w/ warm (maybe very warm) interludes.  I did NOT think that several weeks ago.  However, I think winter is showing a bit of its hand.  

-If I was going to re-write my winter forecast, it would be similar.  HOWEVER, I think winter returns during January.  

-I have been super uneasy(and have stated that) about this winter.  We may struggle to get to La Nina status.  Why is that important here?  The SER will have trouble holding all winter IMHO.  A moderate or strong La Nina?  Get out the Bermuda shorts and don't put away the lawn mower.  A weak La Nina?  Wicked cold to the Apps and beyond w/ maybe even some Piedmont ice/snow.  

-Bottom line....climatology for weak La Ninas in this area is IMHO the best, single predictor of cold winters here.  I will take that ENSO state over all others.  And that gives me great, great pause.  I still lean warm for winter, but Mother Nature could yank that carpet out at any time.

What I don't like:

PDO

MJO tendencies towards warm phases(but this winter could be one of those that bucks the trend....if my suspicion about the EPO as the driver is correct....the EPO trumps the entire pattern)

The cold is just a bit early.  I like cold to show up just before or after Christmas.

Analog in play:

95-96....Cold came in waves, and snow moved along that boundary at times during the winter.  

Today's 8-14 analogs:

John and Boone can fish the info out of theses.  I think there are some decent ones in there...

19891217
19561202
19511211
19551214
19761203
20081205
19631213
19611210
19641121
20001207

One last note:  

The ingredients are there for an early season snowstorm, and maybe more than one.  No guarantees, but that is wild given how warm it has been.

I'm with you on your thinking now. I am much cooler on my thoughts than previously however. SST changes in the Pacific and Atlantic key Domains along with what looks like the tendency for Alaskan Ridging and some Greenland blocking.

    The west pac hot blob has cooled considerably lately. The GOA is still cool but, so is the SST around the Aleutians. That can alter a constant GOA LP setup. Nina is basically non existent with a semblance more east based if recognized at all. 

The Atlantic cooled rapidly just south of the desired 50-50 area. That favors LP stalling more often around there. That would pump ridging toward Greenland as we have saw recently. There may be times we get that modern -NAO/SER Linkage. Hopefully, that won't be the case. From what I remember that happened when there was no 50-50 and the SST'S there were unfavorable.

     As far as those analogues Carvers, most were decent, average to good in Snowfall. A Couple of the less favorable. 2000-01 was about avg Temperature but below avg snow. 89-90, great record cold December with above avg Snow here but don't think at KTRI. Did a 360 last couple days of Dec and was very mild then on with way below avg. Snow. 2008-9 , near avg. Temp, slightly below Snow. The other's near avg to cold with avg to above Snow.

      

[matt9697]

17 hours ago, Carvers Gap said:

Saddle up!  Here we go!!!  The Weeklies ext(Euro) have the Christmas warm-up, but then they move back to seasonal which is plenty good during early January.  I lean warm for winter overall with a cold start.  That said, the weaker this ENSO gets....the more we are dealing with an SST forecasting bust which is in progress.  If this goes Nada...probably still warm.  But....... a weak La Nina has to be accounted for in terms of cold intrusions.  It also brings a new set of analogs into play if one uses analogs.  I guess what I am saying is that my original forecast is probably busted right now as we speak.  If it was Monopoly, I would say, "Bank error in your favor.  Go collect $200."  This first cold shot could be a one-off.  That has certainly been the case for the last few Nina winters....cold until Christmas and then torch.  However, in middle and western areas of the forum, winter returned during a couple of winters to historic levels.  

What I like looking at LR forecasting:

-Sometimes we can't get it to snow at all when the cold comes around.  In LR modeling, snow is accompanying the cold at varying latitudes east of the MS.

-The late landfalling hurricanes do have some correlation to wild winters here. 

-We haven't had any early season snowfalls...seems to be the kiss of death for bad winters IMBY.

-There is cold in North America.\

-I tend to think the EPO is going to be the driver through the first half of winter w/ warm (maybe very warm) interludes.  I did NOT think that several weeks ago.  However, I think winter is showing a bit of its hand.  

-If I was going to re-write my winter forecast, it would be similar.  HOWEVER, I think winter returns during January.  

-I have been super uneasy(and have stated that) about this winter.  We may struggle to get to La Nina status.  Why is that important here?  The SER will have trouble holding all winter IMHO.  A moderate or strong La Nina?  Get out the Bermuda shorts and don't put away the lawn mower.  A weak La Nina?  Wicked cold to the Apps and beyond w/ maybe even some Piedmont ice/snow.  

-Bottom line....climatology for weak La Ninas in this area is IMHO the best, single predictor of cold winters here.  I will take that ENSO state over all others.  And that gives me great, great pause.  I still lean warm for winter, but Mother Nature could yank that carpet out at any time.

What I don't like:

PDO

MJO tendencies towards warm phases(but this winter could be one of those that bucks the trend....if my suspicion about the EPO as the driver is correct....the EPO trumps the entire pattern)

The cold is just a bit early.  I like cold to show up just before or after Christmas.

Analog in play:

95-96....Cold came in waves, and snow moved along that boundary at times during the winter.  

Today's 8-14 analogs:

John and Boone can fish the info out of theses.  I think there are some decent ones in there...

19891217
19561202
19511211
19551214
19761203
20081205
19631213
19611210
19641121
20001207

One last note:  

The ingredients are there for an early season snowstorm, and maybe more than one.  No guarantees, but that is wild given how warm it has been.

I like my chances in Middle TN; most of the Winters in the 60's were good for my area; 1976-1977 was the first of the trifecta winters I recall from childhood! 

[Carvers Gap]

The 12z Euro AI is just ridiculously cold for day 10-16.

[matt9697]

49 minutes ago, Carvers Gap said:

The 12z Euro AI is just ridiculously cold for day 10-16.

Are those negative numbers? That is crazy, bound to have snow on the ground to get that

[beavis1729]

1 hour ago, Carvers Gap said:

The 12z Euro AI is just ridiculously cold for day 10-16.

Yeah, very impressive. Of course it’s an operational run way out there, but here are the Day 14 temp departures.

 

[Daniel Boone]

21 minutes ago, beavis1729 said:

Yeah, very impressive. Of course it’s an operational run way out there, but here are the Day 14 temp departures.

 

Looks like it wants to continue a-EPO and -NAO. 

[Carvers Gap]

1 hour ago, beavis1729 said:

Yeah, very impressive. Of course it’s an operational run way out there, but here are the Day 14 temp departures.

 

Good catch.  I was thinking this setup is purely PAC driven.  That being crazy cold to this area.  The 18z ensembles generally supports that look. Edit: Sorry, I though that was the 18z GFS which John notes (Below) is powerful.

[John1122]

The GFS also ended with a power house cold front pressing into the area. One of those that has 65 degrees on one side and 20 on the other side, with below zero temps in Missouri. 

[Carvers Gap]

Modeling could be a bit too quick, but they generally are showing a very cold regime Dec 1-7 at least.  

[Carvers Gap]

This is pretty cold for a 7-day ensemble at range.  That means reality could be much colder.  Almost 20 degrees below normal at this range is a big number.  Now, this could change, and we have seen these looks evaporate or just be a 7-10 days too early.  Something to watch, but super impressive.  That is an overrunning look if I have ever seen one.  Somewhere between I-40 to the Ohio River looks like it could be the track.

 

[Carvers Gap]

Surface pressure (Euro Weeklies ext) is very much EPO driven.  Cold goes down the front range and spread quickly eastward.  The only thing to watch is if modeling tucks that trough under the EPO ridge into the Mountain West.  That means cold would come down the west slopes of the Rockies.  However, I feel given the time of year that the cold will drain down the front range and race eastward.  This is a cold and storm pattern.  Precip is normal to above for the forum area during December.  This would allow for a January thaw and potentially winter returning later in January.  It is a good thing that we are seeing this in November as the winter will often repeat November patterns.

This is a 30 day map!  That is Alaska cold with a great mechanism to get it south eastward.

 

[*Flash*]

I do think our warmer periods will be more frequent throughout the winter but I also think our source regions won't struggle to get fed, fill up, and overflow thanks to that -EPO. The visual that comes to mind ironically stems from the summer months during which I take my kids to the splash pad often. Those big buckets? They're filling up every 50 seconds as hyper littles scatter beneath. But those 10 seconds from the point the bucket starts to tilt to complete splashdown are glorious. Our 2024-25 winter in a nutshell.

[Daniel Boone]

1 hour ago, *Flash* said:

I do think our warmer periods will be more frequent throughout the winter but I also think our source regions won't struggle to get fed, fill up, and overflow thanks to that -EPO. The visual that comes to mind ironically stems from the summer months during which I take my kids to the splash pad often. Those big buckets? They're filling up every 50 seconds as hyper littles scatter beneath. But those 10 seconds from the point the bucket starts to tilt to complete splashdown are glorious. Our 2024-25 winter in a nutshell.

The current -EPO, the longer it holds the more those SSTS warm in the GOA . The more these LP's continue to traverse over the area around Newfoundland and off the NE Coast, the colder those SST'S will get and in turn should feedback and allow for better odds of a colder Winter than pretty much all of us have been expecting due to it pumping up Greenland blocking. The building +QBO will resist that the further we get in Winter though. 

   if some mechanism locks the opposite pattern in long enough it could go back to where we were going . In 89-90 that actually happened after a solid cold December. The Pattern did an unusual sudden 360 flip by New Years day. The MJO will probably foul us up a few times but, it appears as of now it may be more prone to be low amp with less influence. Hopefully that's the case. 

  Just my antique 2 cents worth (if that).

[John1122]

GFS opens December with the big winter event again this run. The Canadian looks like it was heading that way too. The GFS had the same storm in the 11-29 to Dec 1stish time frame the other day too.

[Save the itchy algae!]

Glad to be out of my slumber, bring on December!


.

[Carvers Gap]

The 6z GEFS ensemble is about as cold as one can get at this range.  Some questions that I don't have the answer to regarding this cold air intrusion...

1.  Duration of the event?  Best guess is very late November into mid-December, and maybe right up to the week prior to Christmas.  Then we see a thaw o sorts.

2.  Does the pattern reload with more than one cold air mass or is this just a 7-10 day cold shot, and then done ?

3.  How much frozen precip falls?  There is certainly an active precip pattern predicted.  I think the risk of an overrunning event for middle and west TN is increasing.  However, an ana front like we saw at Christmas(but not Christmas this time) a few years ago is probably also on the table.

4.  Does winter return(if it arrives) after December?  Big question w/ lots of differing opinions.  With the ENSO forecast busting badly, I think that will cause some unseen downstream forecast problems, especially in LR ext modeling(as it continues to change in order to handle the new SST data).  The climatology changes IMHO if this is a very weak Nina.  My original winter forecast....climatology might not apply.  Weak Nina climatology argues for a mid-winter thaw, and then more snow and cold later in January and early Feb.

For now, I remain cautiously optimistic(if one can say that given the human suffering left by Helene) that winter is on its way, and that some in the forum area will see wintry precip.  This season I do pause a bit with the celebration of the return of winter.  I know folks in the mountains are in a tremendously bad spot - roads, homes, heating sources still being put into place.  The good thing lately is that it has been dry, but extreme cold would add insult to injury.  Hopefully responding agencies are looking at longterm forecasts for December, and are moving heat sources into place.  Those warm interludes between cold shots would definitely be helpful.  So, if it gets warm at times during the winter....it is probably appreciated by those impacted by Helene.  Mountain people are tough though.  They have lived through severe cold before.  

On a final note, I know JB talks a lot about late season hurricanes being correlated to December cold...that looks to possibly verify.  Some of the cold showing up on modeling would be cold even in the middle of winter.