January 2021 Medium/Longterm Pattern Discussion.

[Daniel Boone]

1 minute ago, Carvers Gap said:

Saw a post on another forum(maybe MA), where the strat warm stuff may be causing some of this for early January modeling.  Seems like 2-3 winters ago, we had a January that looked great on LR modeling, and the strat warm pretty much wrecked havoc on that.  Makes me wonder if we are about to see large scale changes(could be really good or the opposite) after mid-January.  The SSW could have a hand in that look as well.  

Ah, I remember now(forgive the stream of thought post!)...the MA referenced a tweet about the eastern US being warmer than normal during the events leading up to a strat warm.   LOL- heck, I have even talked about it, but always forget when it happens in modeling.   When there is a massive ridge along the east coast of NA(basically a WAR on steroids...talking like Cuba to Greenland), that has preceded the last 2-3 SPV splits.  

Have to admit, I am not excited about this strat split scenario...but it does open the door for very cold air(due to the NAO) to enter the east after the split.  Just going to depend on which side of the globe the coldest air goes.

  yep. Like you brother,  I'd read on it somewhere a few days ago and it had completely slipped my mind. ( product of being an antique on my part I guess. I'll blame it in that anyway). With the current pattern, I'd about rather it not happen as well.  That one you mention actually ruined a good pattern for us. It helped the Rockies. ( as if they need any irt Snow, lol.).

[Daniel Boone]

42 minutes ago, Carvers Gap said:

Saw a post on another forum(maybe MA), where the strat warm stuff may be causing some of this for early January modeling.  Seems like 2-3 winters ago, we had a January that looked great on LR modeling, and the strat warm pretty much wrecked havoc on that.  Makes me wonder if we are about to see large scale changes(could be really good or the opposite) after mid-January.  The SSW could have a hand in that look as well.  

Ah, I remember now(forgive the stream of thought post!)...the MA referenced a tweet about the eastern US being warmer than normal during the events leading up to a strat warm.   LOL- heck, I have even talked about it, but always forget when it happens in modeling.   When there is a massive ridge along the east coast of NA(basically a WAR on steroids...talking like Cuba to Greenland), that has preceded the last 2-3 SPV splits.  

Have to admit, I am not excited about this strat split scenario...but it does open the door for very cold air(due to the NAO) to enter the east after the split.  Just going to depend on which side of the globe the coldest air goes.

Isotherm just posted an excellent explanation on what we're discussing Carvers, in the MA forum. Makes sense.

[PowellVolz]

Saw a post on another forum(maybe MA), where the strat warm stuff may be causing some of this for early January modeling.  Seems like 2-3 winters ago, we had a January that looked great on LR modeling, and the strat warm pretty much wrecked havoc on that.  Makes me wonder if we are about to see large scale changes(could be really good or the opposite) after mid-January.  The SSW could have a hand in that look as well.  
Ah, I remember now(forgive the stream of thought post!)...the MA referenced a tweet about the eastern US being warmer than normal during the events leading up to a strat warm.   LOL- heck, I have even talked about it, but always forget when it happens in modeling.   When there is a massive ridge along the east coast of NA(basically a WAR on steroids...talking like Cuba to Greenland), that has preceded the last 2-3 SPV splits.  
Have to admit, I am not excited about this strat split scenario...but it does open the door for very cold air(due to the NAO) to enter the east after the split.  Just going to depend on which side of the globe the coldest air goes.

Was that the year where the cold was 2 weeks away the whole winter until March?


.

[John1122]

The EURO shifted south with it's frozen shield at 12z and isn't bad for West Tennessee. I suspect it and the GFS will eventually meet. It seems like it's been folding towards the GFS this winter.  

[Carvers Gap]

1 hour ago, PowellVolz said:

Was that the year where the cold was 2 weeks away the whole winter until March?


.

Can't remember.  We had one winter where it was pushed back and pushed back...then had an and SSW...and had more snow in March than the rest of winter.  I am thinking this(the one where the SSW screwed things up) was 17-18 when we had that really cold last half of December.  Then, it went to crap.  LOL.   That said, some truly great winters have had SSWs during early January.  

[Carvers Gap]

2 hours ago, Daniel Boone said:

  yep. Like you brother,  I'd read on it somewhere a few days ago and it had completely slipped my mind. ( product of being an antique on my part I guess. I'll blame it in that anyway). With the current pattern, I'd about rather it not happen as well.  That one you mention actually ruined a good pattern for us. It helped the Rockies. ( as if they need any irt Snow, lol.).

After a decade and a half of really bad winters, the Mountain West had some great winters in the 2010s...stellar type stuff.

[John1122]

GFS shifted towards the Euro that run.  Might have a thread called "AMZ's New Years Rockin Eve" or something like that if the west shifts can stop now.

[John1122]

After getting .20 to .60 or so of freezing rain West Tennessee, West KY and NE Arkansas gets this. 

[Holston_River_Rambler]

In 18-19 the Jan SSW seemed to help fuel the convection of the MJO in the 4/5/6 areas.  Hopefully, if there is a connection between the cooler temps at high altitudes in the tropics and enhanced convection, we can time it better just as some convection flares up over the western Pac areas:

 

If it happened right now, and the above helps reignite convection, I'm not sure it wouldn't just sit over the areas it is now looks like mostly 5 to me:

 

 

I think the strat. is a done deal now. Something is going to happen to mess with it. As to how it unfolds, whether or not it qualifies as a SSWE, whether or not there is a displacement or split,  and if it helps NA pattern or not, those are the big questions. 

The 17-18 happened around mid Feb or so, and that one did result in a nice pattern, it just took a month for the eastern areas on North America to benefit from its repercussions, and by them we just had a grey, rainy, cold, spring. 

For now the Pac jet extension is coming and until we navigate that I think the ensembles will look nasty at times in the LR. That's not to say there isn't a chance of the storm we've been seeing for New Years, I don't mean to imply that at all. Just blah ensemble means like this:

 

For reference and discussion (if any are interested in looking at them) here is the pattern in mid Feb 2018 that proceeded the SSW:

 

~A month later:

A low can't cut, but it is a bit late in climo for us. 

 

I will try to dredge up some more of these type of gifs while we wait for the strat to do its thang. Maybe we can try to get a hint at what could happen.

 

 

 

[Holston_River_Rambler]

 

Recent article (as in Dec. 2020) (no paywall) by Drs. Amy Butler and Daniela Domiesen on SSWEs and their tropospheric impacts

https://www.nature.com/articles/s43247-020-00060-z

 

There'll be a pop quiz on Monday, lol. 

I'll be honest, I haven't read it yet, but though some of us might be interested. I'll probably read it in the AM. 

[Carvers Gap]

SSW is going to be a real pain in the butt from a model standpoint.  The GFS successfully forecast an SSW split in March of 2018 from 16 days out.  March was frigid.  Think the following winter (18-19), we had a good pattern forecast at some point that winter...the SSW "split" and we lost that look in the LR.  We had a great start to winter in 2018 here in TRI, and then the pattern evaporated. All of that said, early season strat splits in late December and early January have led to some great winter patterns in the East which featured very abrupt changes.  Right now, we are about to substitute a decent pattern(like early Dec 2018) for one that could be great or could be spring.  I have seen modeling flip on a dime to really cold or really warm.  They are quite random in where they place the lobes of cold which break off - like going to Vegas.  I really don't like the trends of LR modeling during the past 36 hours.  They could flip back once the strat warm is "felt," but I lost my enjoyment of SSW stuff in 18-19. LOL.  Give me March 2018 in January...but not a fan of LR modeling trends right now.  That said, if the SSW is going to be felt, count forward a couple of weeks from the SPV split(assuming the TPV also splits), and that should be when we see changes at our latitude.  @Holston_River_Rambler, when is the exact time frame of that split.

[Holston_River_Rambler]

This is kinda what I've been looking for on Twitter (my gifs don't go back far enough to see the pattern from 17 - 18 or 18 - 19:

Here are the key images from his presentation:

 

 

 

 

 

 

 

[Holston_River_Rambler]

@Carvers Gap

Butler actually has a nice plot to answer the timing question and she seems encouraged that this one might couple with the troposphere, unlike the one in 18 - 19

 

Here is the 12z Euro OP. Looks like it gets cranking around Jan 3 - 5. 

[Holston_River_Rambler]

Looking at Ventrice's research, it looks like this one is being generated over Siberia (like the one we don't like: 2018 - 2019).

Compare Ventrice's images form 2019, to that EPS gif above, very, very similar. 

 

That one never coupled though with the troposphere though. Will this one? 

 

 

[Carvers Gap]

I think the 18-19 coupled with the TPV - is that the year we got the twin vortices or was that last year?

....Very much looks like the lobes of the TPVs go to western Europe and the other rotates into Alasks(and then retrogrades back into eastern Siberia).  I really cannot overstate my disdain for what I am seeing with this SSW.  Ugh.  

[Holston_River_Rambler]

I don't think the 18-19 one coupled and that was why it didn't do much. I could be misremembering though. Yeah, if this one happens like that one, it could just crank up the Nina base state. Isotherm and Griteater remain optimistic for January though, so I'll trust them and wait and see. 

[Carvers Gap]

What we want to see is what the 18z GEFS did.  The eastern ridge fires during week 2 of January, but a trough sneaks in underneath it.  That allows a western ridge to fire.  Once could imagine that allowing very cold air during the second half of January to slide into that trough.  That said, I am not chasing cold into the second half of January this year.  If it happens, it happens...but I won't be tracking that(not after last year's persistent fail on that). The  worst case scenario is the 12z EPS and 12zCVSv2 extended....-NAO connects to an eastern ridge and never relents.  Like Boone, runs counter-intuitive for a summer pattern to develop during winter, but I have seen it happen.  However, La Nina climatology favors a trough in the West.  Enough Grinch from me this evening.  LOL.  Needless to say, I don't like the trends after d10, but as we know...that can still change.  This will flip quickly if it is going to change.  That flip might not be seen for another week or two(speaking of cold if the split occurs).

[Holston_River_Rambler]

The patterns the ensembles were spitting out for the 10 - 15 day range for the SSWE in 2018 - 19 look good. I can't remember if they ever materialized though:

 

 

I feel like we got a nice arctic front and the "Dayton leeside micro low storm" that produced for some eastern areas (n. sevier and blount counties) I'll have to go back and look. 

[Carvers Gap]

Areas of "blue" for the SPV don't necessarily imply cold at the surface - sometimes it is the opposite right?  I was looking at the GFS with its split at 18z....looks like the cold in NA is under the warmer strat anomalies. .  50mb will tell us a little better where the split goes, but for now...we need to be hoping this doesn't couple with the TPV IMHO.   Again, there can be great years with TPVs and modeling could flip cold at the last minute.  IMHO(and it is only an opinion) is that this SSW would not be an improvement to the pattern which we are currently in.  It might be time to get my seed order prepped ASAP if this SSW goes the way I think it could.    I will still hold out hope that it goes the way of some great winters.  Be a tough pill to swallow if this SSW ruins this pattern.

 

[Holston_River_Rambler]

Yeah. I just look at the SPV to see what’s up with it, not for cold or anything like that. IMO we are gonna have to just wait it out and see what happens after the “event” (whatever that turns out to be for the SPV). I’ll try to dig through some analogues tomorrow for a similar situation, but we should probably weight the 2019 one pretty heavily, given SSTs. 

[Carvers Gap]

Just now, Holston_River_Rambler said:

Yeah. I just look at the SPV to see what’s up with it, not for cold or anything like that. IMO we are gonna have to just wait it out and see what happens after the “event” (whatever that turns out to be for the SPV). I’ll try to dig through some analogues tomorrow for a similar situation, but we should probably weight the 2019 one pretty heavily, given SSTs. 

See what you can find.  Seems like opinions are split(pun intended) on whether this is good for eastern NA.  Watching the GEFS extended run right now.  Look like a very warm week 2 of Jan with some hope for week 3.  Will update in a bit.  Watching Liberty and Coastal Carolina.  Thanks for your updates!

[Carvers Gap]

Yeah, the GEFS extended has flipped warm with a ridge along the eastern seaboard after the first week of Jan.  I would imagine there would be intrusions of cold west of the Apps...colder the further west one goes.  Maybe a Montana to Tennessee special at times.  Overall, warm look(after Jan 7th) w a maybe one trough rolling through after the 7th.  Pretty big changes, but it does bounce around some.  

[John1122]

Looking at SSW events between 1958 and 2002, if the SSW happened in December/January in most cases the 60 day snowfall here was above average. If it happened in February or another month, snowfall was more often below average for the next 60 days. 

[Daniel Boone]

I'm not saying alot now other than along the lines of earlier opinion and Carvers in that Id rather the SSW wouldn't happen.  Pattern we have been steadily moving n2 would be great going into January. 

[Carvers Gap]

The 18z CFSv2 Extended has flipped back to cooler for the last three weeks of January...but it has a much different MJO. Good point, @John1122.  Yeah, this pattern would have been gold in Jan, @Daniel Boone.  Let's hope this is one of these winters where the warm just never shows up in real time.  It may well be that the pattern we move to would be that of 95-96(lite) where the cold stretches from MT to TN...models just aren't there yet.  GEFS extended does hint at that after a couple of weeks of ridging in the East for weeks 2-3 of Jan.

[John1122]

This is the composite 0-60 day snowfall from 1958-2014 after all SSW events, both splits and disruptions. The lightest blue is a 10 percent increase in average snowfall the darkest is up to a 50 percent increase. I had to drop and rotate to get a decent look at the United States. 

Our forum region does as well as any other area in North America after a SSW. 

[John1122]

Looking at that image, the biggest snow drought area is basically over the NAO region. I wonder if that's a result of a -NAO there after SSWs?

[Carvers Gap]

6 minutes ago, John1122 said:

Looking at that image, the biggest snow drought area is basically over the NAO region. I wonder if that's a result of a -NAO there after SSWs?

Would about have to be...I think.  

[Carvers Gap]

Again, the 18z GEFS (or some variation) is a possibility for continued winter or a tough that extends from say Calgary to Kentucky.  Those two set-ups have some prior precedent with a -NAO be a constant.  

[jaxjagman]

My storms never work out,i'm still looking at the storm towards the 2nd week of Jan.The pattern looks up and down.We should have a trough new years which looks imminent right now  then a warm up then a system towards the end of week one into two.Right now it's just meh looking