December Medium/ Long Range

[psuhoffman]

4 hours ago, Ralph Wiggum said:

I remember a pattern like this a few years back sorry I don't recall specifically, but there was a sprawling 500mb ridge across Canada, we'll thought this has got to produce, and I'm almost certain we got shutout due to temp issues and cold air source blocked.

2021 

[rjvanals]

29 minutes ago, psuhoffman said:

2021 

If we’re talking about Jan/Feb 2021 we got unlucky as the storms hit to the south of DC or just north of DC https://www.washingtonpost.com/weather/2023/12/27/dc-snow-hole/

We also had the storm around Presidents’ Day where a small warm layer at ~5000 ft turned a 6-10 inch snow event into a sleet fest around DC despite cold low level temps.

We probably had a bottom 10 percent outcome for that set up and I’d take our chances w it again. 

[psuhoffman]

2 hours ago, CAPE said:

It's a bit wonky the way it forms and as advertised it doesn't become the classic rex block with a low in the 50-50 position(trough is displaced further out in the N Atlantic). No cold air around  until the ridge goes up out west. Lets see how persistent it is as we get colder air in place. If it doesn't block/divert the flow and keep HP locked in to our north with storms tracking underneath then it isn't very useful lol. We have seen this pretty frequently in recent winters.

It's not a block, but it is a high latitude ridge.  Yes there is a difference and a true block which always evolves from retrogression or wave breaking is better and that pattern is the best for HECS hunting.  But not all -AO/NAO periods come from retrogression sometimes they can evolve from progression of a heat ridge into Canada and those correlate to snow here also!  No not as much as the perfect unicorn retrograding block.  But a regular good old high latitude heat ridge is still a legitimate way historically for us to get a snowstorm.  This evolution is actually almost identical to what lead to the Feb storm in 2006.  

The pattern started with a full latitude head ridge in the east which got undercut from the west through pattern progression and lead to this...

It's a baby steps thing...what we are looking at around New Years would have to be step one of a process that could lead to a favorable snowstorm pattern here a week later IF things go the right way.  

As for the hyper focus on the EPO... yea it would be helpful if the EPO delivers cold, but there is a reason the EPO along has absolutely no positive correlation to snowfall here!  NONE, ZERO ZIP.  Actually when I looked at every warning snowfall at BWI since 1950 the EPO of all the major indices I evaluated was the least important.  I think more snowstorms happened with a +EPO than negative.  

The fact is we don't just need cold air, we also need a longwave pattern that favors wave amplification at our longitude!  An EPO ridge absent other factors does not do it.  An EPO with a positive AO/NAO actually places us in a northwest flow and waves are washing out on approach.  It's really hard to get a snowstorm in that look.  Worse, without any AO/NAO help when we do get a jet transition and an amplified wave comes along its not going to meet any resistance and so the return flow ahead of it warms our thermals before it arrives...we are too close to the backside of the trough and the warmth is lurking too close to our west for that to work absent other factors like blocking.   Cold dry, warm wet.  That's a typical EPO driven pattern!  No not every single one, once in a while you get super lucky with a year like 2014 or 2015 or some fluke hits like in 2022, but that is the less likely outcome....its much more likely that pattern does not lead to a snowstorm.   Just because most of our snow the last 8 years has come that way does not mean its now the best way to get snow...that is the reason the last 8 years has been by far not even close the least snowy 8 year period in our regions history!  Yes if that kind of pattern persists over and over and over we will luck and fluke our way to some random snow once in a blue moon...but it will continue to be the way it has the last 8 years with below avg snowfall years and scraping by with long stretches of frustration.  An epo driven pattern is not going to be our most likely path to breaking out of this and having a truly snowy period or getting a legit area wide snowstorm.  And sure we take what we can get, if scraps is all we can get eat them....but we don't control any of this so why not root for more?  It's ok to realize we probably aren't going to win the lottery, but its ok to root for it!  

 

Lastly, if we get a pacific to atlantic ridge bridge up top (and those are rarely blocks) and its just not cold enough...the pattern isn't the problem...its just become too warm is!  This is a matter of degrees, sure you can do the whole move the goalposts thing and say well...if that is too warm now we also need the EPO ridge AND we need there to not be a torch period ahead of the longwave pattern, and we need cross polar flow and we need....OMFG at that point it sounds like we live in Atlanta now and the truth is its just not gonna snow much and its probably not worth even tracking.  I mean even in Florida there is some checklist of anomalous factors that if they all lined up could lead to snow...but the point is their checklist is 25 things long and so its just rarely ever going to happen.  If our checklist starts to go from 3 things to 8 or 10 or 15 at some point we've entered the "its just not gonna snow much" territory.  But just because we have a thermal issue now does not mean the AO and NAO are suddenly less important, there is no evidence of that...it just means we are snowing way less.  We still need those other factors to line up to have a good chance of a snowstorm...we just also now need MORE.  

[Ralph Wiggum]

36 minutes ago, psuhoffman said:

2021 

That's it. Pretty sure that was the year of the epic unicorn LR ensemble pattern as well. That ridging in central Canada was forecast to progress into the NAO region across the ensembles and become an epic block....our savior. Iirc it ended up being too much of a good thing?

[psuhoffman]

BTW, given my modest snowfall forecast for this winter...I did not expect nor predict we do get a big snowstorm...or even a moderate one...to get to those numbers we just need a few minor events.  But that does not mean there is no chance and that I am not rooting for it.  Just because I expect it to be a horrible year doesn't mean I don't want it to turn out better or that I am not looking for the chance it does.  Flukes happen.  2000 was a god awful horrible pattern 90% of that winter...it very well could have ended the same as 2002 or 2008 or 2012 as a complete dud...but we got one week with a decent pattern and hit the lottery.  I am rooting for that again.  That can happen in any year, nina or not.  

[Ralph Wiggum]

3 minutes ago, psuhoffman said:

It's not a block, but it is a high latitude ridge.  Yes there is a difference and a true block which always evolves from retrogression or wave breaking is better and that pattern is the best for HECS hunting.  But not all -AO/NAO periods come from retrogression sometimes they can evolve from progression of a heat ridge into Canada and those correlate to snow here also!  No not as much as the perfect unicorn retrograding block.  But a regular good old high latitude heat ridge is still a legitimate way historically for us to get a snowstorm.  This evolution is actually almost identical to what lead to the Feb storm in 2006.  

The pattern started with a full latitude head ridge in the east which got undercut from the west through pattern progression and lead to this...

It's a baby steps thing...what we are looking at around New Years would have to be step one of a process that could lead to a favorable snowstorm pattern here a week later IF things go the right way.  

As for the hyper focus on the EPO... yea it would be helpful if the EPO delivers cold, but there is a reason the EPO along has absolutely no positive correlation to snowfall here!  NONE, ZERO ZIP.  Actually when I looked at every warning snowfall at BWI since 1950 the EPO of all the major indices I evaluated was the least important.  I think more snowstorms happened with a +EPO than negative.  

The fact is we don't just need cold air, we also need a longwave pattern that favors wave amplification at our longitude!  An EPO ridge absent other factors does not do it.  An EPO with a positive AO/NAO actually places us in a northwest flow and waves are washing out on approach.  It's really hard to get a snowstorm in that look.  Worse, without any AO/NAO help when we do get a jet transition and an amplified wave comes along its not going to meet any resistance and so the return flow ahead of it warms our thermals before it arrives...we are too close to the backside of the trough and the warmth is lurking too close to our west for that to work absent other factors like blocking.   Cold dry, warm wet.  That's a typical EPO driven pattern!  No not every single one, once in a while you get super lucky with a year like 2014 or 2015 or some fluke hits like in 2022, but that is the less likely outcome....its much more likely that pattern does not lead to a snowstorm.   Just because most of our snow the last 8 years has come that way does not mean its now the best way to get snow...that is the reason the last 8 years has been by far not even close the least snowy 8 year period in our regions history!  Yes if that kind of pattern persists over and over and over we will luck and fluke our way to some random snow once in a blue moon...but it will continue to be the way it has the last 8 years with below avg snowfall years and scraping by with long stretches of frustration.  An epo driven pattern is not going to be our most likely path to breaking out of this and having a truly snowy period or getting a legit area wide snowstorm.  And sure we take what we can get, if scraps is all we can get eat them....but we don't control any of this so why not root for more?  It's ok to realize we probably aren't going to win the lottery, but its ok to root for it!  

 

Lastly, if we get a pacific to atlantic ridge bridge up top (and those are rarely blocks) and its just not cold enough...the pattern isn't the problem...its just become too warm is!  This is a matter of degrees, sure you can do the whole move the goalposts thing and say well...if that is too warm now we also need the EPO ridge AND we need there to not be a torch period ahead of the longwave pattern, and we need cross polar flow and we need....OMFG at that point it sounds like we live in Atlanta now and the truth is its just not gonna snow much and its probably not worth even tracking.  I mean even in Florida there is some checklist of anomalous factors that if they all lined up could lead to snow...but the point is their checklist is 25 things long and so its just rarely ever going to happen.  If our checklist starts to go from 3 things to 8 or 10 or 15 at some point we've entered the "its just not gonna snow much" territory.  But just because we have a thermal issue now does not mean the AO and NAO are suddenly less important, there is no evidence of that...it just means we are snowing way less.  We still need those other factors to line up to have a good chance of a snowstorm...we just also now need MORE.  

Epic post PSU.

[psuhoffman]

Just now, Ralph Wiggum said:

That's it. Pretty sure that was the year of the epic unicorn LR ensemble pattern as well. That ridging in central Canada was forecast to progress into the NAO region across the ensembles and become an epic block....our savior. Iirc it ended up being too much of a good thing?

Also 2019, its happened a few times lately, it also happened in Dec more recently.  The combo of our source regions being torched and mid latitude warmth caused the SER to link up with the NAO block multiple times recently.  But we still need that longwave configuration we just need it to not be too warm when it happens, and no I don't know how we magically make that happen...but a pattern that puts us on the backside of a trough with no blocking to hold the cold in when an amplification happens is not a winning formula either.  

[brooklynwx99]

23 minutes ago, Ralph Wiggum said:

That's it. Pretty sure that was the year of the epic unicorn LR ensemble pattern as well. That ridging in central Canada was forecast to progress into the NAO region across the ensembles and become an epic block....our savior. Iirc it ended up being too much of a good thing?

there was a HECS in Feb 2021 that just missed you guys to the north

[CAPE]

3 hours ago, psuhoffman said:

It's not a block, but it is a high latitude ridge.  Yes there is a difference and a true block which always evolves from retrogression or wave breaking is better and that pattern is the best for HECS hunting.  But not all -AO/NAO periods come from retrogression sometimes they can evolve from progression of a heat ridge into Canada and those correlate to snow here also!  No not as much as the perfect unicorn retrograding block.  But a regular good old high latitude heat ridge is still a legitimate way historically for us to get a snowstorm.  This evolution is actually almost identical to what lead to the Feb storm in 2006.  

The pattern started with a full latitude head ridge in the east which got undercut from the west through pattern progression and lead to this...

It's a baby steps thing...what we are looking at around New Years would have to be step one of a process that could lead to a favorable snowstorm pattern here a week later IF things go the right way.  

As for the hyper focus on the EPO... yea it would be helpful if the EPO delivers cold, but there is a reason the EPO along has absolutely no positive correlation to snowfall here!  NONE, ZERO ZIP.  Actually when I looked at every warning snowfall at BWI since 1950 the EPO of all the major indices I evaluated was the least important.  I think more snowstorms happened with a +EPO than negative.  

The fact is we don't just need cold air, we also need a longwave pattern that favors wave amplification at our longitude!  An EPO ridge absent other factors does not do it.  An EPO with a positive AO/NAO actually places us in a northwest flow and waves are washing out on approach.  It's really hard to get a snowstorm in that look.  Worse, without any AO/NAO help when we do get a jet transition and an amplified wave comes along its not going to meet any resistance and so the return flow ahead of it warms our thermals before it arrives...we are too close to the backside of the trough and the warmth is lurking too close to our west for that to work absent other factors like blocking.   Cold dry, warm wet.  That's a typical EPO driven pattern!  No not every single one, once in a while you get super lucky with a year like 2014 or 2015 or some fluke hits like in 2022, but that is the less likely outcome....its much more likely that pattern does not lead to a snowstorm.   Just because most of our snow the last 8 years has come that way does not mean its now the best way to get snow...that is the reason the last 8 years has been by far not even close the least snowy 8 year period in our regions history!  Yes if that kind of pattern persists over and over and over we will luck and fluke our way to some random snow once in a blue moon...but it will continue to be the way it has the last 8 years with below avg snowfall years and scraping by with long stretches of frustration.  An epo driven pattern is not going to be our most likely path to breaking out of this and having a truly snowy period or getting a legit area wide snowstorm.  And sure we take what we can get, if scraps is all we can get eat them....but we don't control any of this so why not root for more?  It's ok to realize we probably aren't going to win the lottery, but its ok to root for it!  

 

Lastly, if we get a pacific to atlantic ridge bridge up top (and those are rarely blocks) and its just not cold enough...the pattern isn't the problem...its just become too warm is!  This is a matter of degrees, sure you can do the whole move the goalposts thing and say well...if that is too warm now we also need the EPO ridge AND we need there to not be a torch period ahead of the longwave pattern, and we need cross polar flow and we need....OMFG at that point it sounds like we live in Atlanta now and the truth is its just not gonna snow much and its probably not worth even tracking.  I mean even in Florida there is some checklist of anomalous factors that if they all lined up could lead to snow...but the point is their checklist is 25 things long and so its just rarely ever going to happen.  If our checklist starts to go from 3 things to 8 or 10 or 15 at some point we've entered the "its just not gonna snow much" territory.  But just because we have a thermal issue now does not mean the AO and NAO are suddenly less important, there is no evidence of that...it just means we are snowing way less.  We still need those other factors to line up to have a good chance of a snowstorm...we just also now need MORE.  

I'm rooting for 2009-10 style blocking, but I doubt it happens. Guidance has been depicting a -EPO tendency going back months with the seasonal tools. And its happening. That's the reality. Ofc we don't want a +AO/NAO. But if you go back and look at some of the good snow events of recent Nina years, we did have a transient -NAO in some, which helped. A legit HL block is probably not in the cards this winter, but something bootleg/transient could work. Getting back to the early Jan period, most ens/extended guidance depict a strongly -EPO, with a modestly negative AO/NAO. All these features wax and wane, which is not easily detected on a mean. So as usual, we will need some luck with timing. Also seeing hints of split flow with a bit of a southern stream.

[psuhoffman]

20 minutes ago, CAPE said:

I'm rooting for 2009-10 style blocking, but I doubt it happens. Guidance has been depicting a -EPO tendency going back months with the seasonal tools. And its happening. That's the reality. Ofc we don't want a +AO/NAO. But if you go back and look at some of the good snow events of recent Nina years, we did have a transient -NAO in some, which helped. A legit HL block is probably not in the cards this winter, but something bootleg/transient could work. Getting back the early Jan period, most ens/extended guidance depict a strongly -EPO, with a modestly negative AO/NAO. All these features wax and wane, which is not easily detected on a mean. So as usual, we will need some luck with timing. Also seeing hints of split flow with a bit of a southern stream.

100!  What has my interest is that we might get a window where there is enough ridging up top that combined with the EPO actually increases our chances of a snowstorm.  Enough that maybe we have a slight chance to buck the odds and get that one hit that can make a season.  That's realistically all I am rooting for...yea we might eek our way to a few minor events, whatever...but honestly what will make or break this season is if we can get lucky, find a small window, and hit big one time.  

[87storms]

18 minutes ago, CAPE said:

I'm rooting for 2009-10 style blocking, but I doubt it happens. Guidance has been depicting a -EPO tendency going back months with the seasonal tools. And its happening. That's the reality. Ofc we don't want a +AO/NAO. But if you go back and look at some of the good snow events of recent Nina years, we did have a transient -NAO in some, which helped. A legit HL block is probably not in the cards this winter, but something bootleg/transient could work. Getting back the early Jan period, most ens/extended guidance depict a strongly -EPO, with a modestly negative AO/NAO. All these features wax and wane, which is not easily detected on a mean. So as usual, we will need some luck with timing. Also seeing hints of split flow with a bit of a southern stream.

09/10 was a fluke with blocking starting by early to mid-Fall and several east coast systems already hitting "the wall".  It was only a matter of time before it snowed in that pattern.

Imo, this winter is showing its hand pretty early as a potentially "run of the mill" winter.  I've already had a couple of snow events, but as typical in December, nothing to go 4 wheeling in.  It's been cold at times and mild at times, but nothing extreme.

[CAPE]

3 minutes ago, 87storms said:

09/10 was a fluke with blocking starting by early to mid-Fall and several east coast systems already hitting "the wall".  It was only a matter of time before it snowed in that pattern.

Imo, this winter is showing its hand pretty early as a potentially "run of the mill" winter.  I've already had a couple of snow events, but as typical in December, nothing to go 4 wheeling in.  It's been cold at times and mild at times, but nothing extreme.

It was epic is what it was. Proper. It developed early in large part from a retrograding Scandi ridge and persisted. True atmospheric block.

Maybe next winter we get the elusive Modoki Nino with blocking, and see how it goes.

[MillvilleWx]

I’ve been thinking if we get any breaks in the LR pattern for snow potential, it would likely occur during January-March. Still thinking we miss on a big one, but as @psuhoffmannoted, it only takes one stroke of timing luck and we can get the goods. I’m out on anything until after the New Years, but I’ll of course keep peeking at what’s to come. 

[87storms]

48 minutes ago, CAPE said:

It was epic is what it was. Proper. It developed early in large part from a retrograding Scandi ridge and persisted. True atmospheric block.

Maybe next winter we get the elusive Modoki Nino with blocking, and see how it goes.

I'm in.  This weather is getting boring lol

[WxUSAF]

16 minutes ago, MillvilleWx said:

I’ve been thinking if we get any breaks in the LR pattern for snow potential, it would likely occur during January-March. Still thinking we miss on a big one, but as @psuhoffmannoted, it only takes one stroke of timing luck and we can get the goods. I’m out on anything until after the New Years, but I’ll of course keep peeking at what’s to come. 

Gfs kinda has this at the end, but I’d expect one or even a couple really wound up cutters around NYD that helps reset the pattern toward a more favorable configuration. If we’re lucky, a proclivity for big precip producers will continue after cold air returns.

[cbmclean]

2 hours ago, Ralph Wiggum said:

That's it. Pretty sure that was the year of the epic unicorn LR ensemble pattern as well. That ridging in central Canada was forecast to progress into the NAO region across the ensembles and become an epic block....our savior. Iirc it ended up being too much of a good thing?

Yes!  2020-21 was a dead ratter from the start.  PSU called it in an epic (and soul-crushing) post on December 30th.  However, at some point in late Jan or early Feb I think all guidance was showing a major pattern improvement which then collapsed when one small detail in the run-up went differently than they foresaw...PSU had an epic post about that as well.  Lot of epic posts from PSU over this bad period.  These years have been bad for snow but good for his literary output.  And I mean that in an appreciative way.

[Maestrobjwa]

6 minutes ago, cbmclean said:

Yes!  2020-21 was a dead ratter from the start.  PSU called it in an epic (and soul-crushing) post on December 30th.  However, at some point in late Jan or early Feb I think all guidance was showing a major pattern improvement which then collapsed when one small detail in the run-up went differently than they foresaw...PSU had an epic post about that as well.  Lot of epic posts from PSU over this bad period.  These years have been bad for snow but good for his literary output.  And I mean that in an appreciative way.

I thought that was 2019-20 that he called the dead ratter? Seems like his outlook was slightly more optimistic for 20-21.

[cbmclean]

3 minutes ago, Maestrobjwa said:

I thought that was 2019-20 that he called the dead ratter? Seems like his outlook was slightly more optimistic for 20-21.

Hmm, I believe you may be right.  We've had so many duds lately they are all beginning to run together.

[brooklynwx99]

this is what you want to see for legit snow opportunities in early Jan

[Eskimo Joe]

6 minutes ago, brooklynwx99 said:

this is what you want to see for legit snow opportunities in early Jan

That's how you get a Feb 2007 over running event.

[WEATHER53]

Other than for 1-2 days I don’t see any protracted warmth until at least 1/10/25 

[WxUSAF]

39 minutes ago, brooklynwx99 said:

this is what you want to see for legit snow opportunities in early Jan

Yes. This I like.

[Eskimo Joe]

1 hour ago, WEATHER53 said:

Other than for 1-2 days I don’t see any protracted warmth until at least 1/10/25 

Need 12/30 to be warm. Trying to pour concrete.

[brooklynwx99]

1 hour ago, WxUSAF said:

Yes. This I like.

even a 50/50 signal as the block decays

[Ji]

14 minutes ago, brooklynwx99 said:

even a 50/50 signal as the block decays

the block is decaying one day after it forms?

[brooklynwx99]

7 minutes ago, Ji said:

the block is decaying one day after it forms?

no, it's actually forming at the end of Dec. this is also a block. it just advects northward and retrogrades. kind of a weird evolution but still a valid one

note the LP dipole in the Atlantic. it's jamming stuff up downstream, so it's not one of those bootleg positive anomalies that does nothing to slow the flow down

[brooklynwx99]

lol this is ridiculous too. 50/50 signal at 2-3 weeks out is kinda wild. this is the kind of stuff we were looking for last year

[cbmclean]

1 hour ago, Eskimo Joe said:

Need 12/30 to be warm. Trying to pour concrete.

We love you EJ, but if necessary we will trade your entire house for the snow...no offence.

[Terpeast]

12 minutes ago, brooklynwx99 said:

lol this is ridiculous too. 50/50 signal at 2-3 weeks out is kinda wild. this is the kind of stuff we were looking for last year

Lets hope the wheels don't come off this one like last Feb.

[brooklynwx99]

4 minutes ago, Terpeast said:

Lets hope the wheels don't come off this one like last Feb.

considering the blocking doesn’t rely on a cutter and the Pacific seems a lot more favorable, this seems a bit more solid

i’d like to give this another week though