Pattern Changing: Early December threats?

[ORH_wxman]

As we already talked about a lot on the first pattern change thread for late November, we see a major dump of cold air into Canada late November and then a mega -NAO block is going to try and filter some of this eastward and southward as we move into early December.

It will not be the Siberian Express like it was for the northern plains, but it should be some modified arctic air that is cold enough to produce some legit snow threats.

The GFS ensemble mean and Euro ensemble mean have generally been in pretty close agreement with eachother for the early December time frame. Using the GFS ensembles, here is an analog composite pattern for December 1st

You can clearly see the huge -NAO block in conjunction with a solidly negative PNA.

This should provide a fairly active storm pattern across the CONUS but with a tendency to not allow storms to cut west of New England....that said, there is no guarantee that cannot happen in any individual perfect setup. Just look at the T-day event. But all else being equal this far out, you'll take your chances.

[CoastalWx]

Like you said, all you can ask for is a chance, and I think we definitely will have our chances.

[MaineJayhawk]

Like you said, all you can ask for is a chance, and I think we definitely will have our chances.

It's a guarantee (ironclad, even) that some weenie will twist your words and have you saying you were locking in 6-12 for 12/3.

[Tropopause_Fold]

MJO charts sort of differ between uk and gfs based products, but could be argued that either is OK. GFS/GEFS (shown) are pushing it into favorable positions (phase 8/1) for New England snow events per the research that Will did (someplace I have a graphic of this that I put together last winter) and for cold per the CPC correlation charts.

UK just sort of stalls the MJO in the circle of death...which could be OK with the coming pattern locking in.

EDIT: let's keep the thread posts solely about the pattern change if possible?

[CoastalWx]

MJO charts sort of differ between uk and gfs based products, but could be argued that either is OK. GFS/GEFS (shown) are pushing it into favorable positions (phase 8/1) for New England snow events per the research that Will did (someplace I have a graphic of this that I put together last winter) and for cold per the CPC correlation charts.

UK just sort of stalls the MJO in the circle of death...which could be OK with the coming pattern locking in.

EDIT: let's keep the thread posts solely about the pattern change if possible?

It's all sort of related.

Here is the work that Gibbs and Will did.

http://www.easternuswx.com/bb/index.php?/topic/212672-snow-events-for-bosorh-by-mjo-phase/

[CoastalWx]

That was some good stuff put together in there. Really neat to see.

[Tropopause_Fold]

It's all sort of related.

Here is the work that Gibbs and Will did.

http://www.easternuswx.com/bb/index.php?/topic/212672-snow-events-for-bosorh-by-mjo-phase/

cool. nice grab. here's the image.

[CoastalWx]

Clearly phases 4-6 are not the best, but it also proves we can do it up this way, thanks to our latitude. That graph would look much difference south of NYC...heck even for NYC.

[ski MRG]

It's a guarantee (ironclad, even) that some weenie will twist your words and have you saying you were locking in 6-12 for 12/3.

Glad Scott's locked us in. His opinion carries a lot of weight with me.

[Tropopause_Fold]

It's all sort of related.

Here is the work that Gibbs and Will did.

http://www.easternuswx.com/bb/index.php?/topic/212672-snow-events-for-bosorh-by-mjo-phase/

which part were you talking about? i think i know what you are saying here, but want to make sure.

[CoastalWx]

which part were you talking about? i think i know what you are saying here, but want to make sure.

Oh, I thought you were questioning bringing in the MJO and Will's research. I figured it's all related to the pattern change stuff.

[cpickett79]

cool. nice grab. here's the image.

i think ralieghwx had that mojo phase 500mb anomaly map by winter month but site is missing?

b/c if i remember correctly it would show...(ex. that a phase 6 may be VERY good in december.....but not so much in march) based on 500mb anomaly maps

[Tropopause_Fold]

Oh, I thought you were questioning bringing in the MJO and Will's research. I figured it's all related to the pattern change stuff.

OH, haha. no. i thought you were talking about the forcings. and kind of saying "duh, Phil - it's obvious".

[CoastalWx]

i wonder how much a difference there is in say phase 6 is for december than say march (i.e months with fairly similiar snowfall ave's). typical 500mb anomalies and such. and so on and so forth with other phases

is this covered in there....and yes i'm looking.

i.e is phase 2 more bullish for snow in dec vs. march and so on

Well, from a physical standpoint, I think there are some differences. In December wavelengths are increasing, while in March they are usually decreasing for one thing. That may have an impact. I'm not sure if we have enough of a sample size to specifically determine what exact phase of the MJO is best for sne in December or March. That's why you always see the trimonthly composites like NDJ, DJF, etc.

[CoastalWx]

OH, haha. no. i thought you were talking about the forcings. and kind of saying "duh, Phil - it's obvious".

LOL not at all. I guess I just interpreted the edit you made as something else.

[weatherwiz]

Woah...there are some pretty good years in the analog composite box...some pretty ****ty years also but the majority of those years were pretty awesome.

[dryslot]

I prefer the modified arctic air over the frigid polar air, Seems more time then not when we get the bone chilling variety we end up dry as well as storms end up getting shunted to the SE here, The signals do remain for a colder 1st part of Dec which looks to be active as well, Thats really all we can ask if the ingredients are there we should be able to get something to come together and fall in place for some Dec snows.........

[ORH_wxman]

Woah...there are some pretty good years in the analog composite box...some pretty ****ty years also but the majority of those years were pretty awesome.

There's several snow events within a few days of each analog too...you have a couple minor events (moderate where Phil is on the Cape) near that 2005 date, and of course if you roll it forward 6 days....

1971 Thanksgiving interior snowstorm is there....Dec 16, 1989 storm is there....a few other smaller events in the composite, but they certainly show that similar patterns have produced something in the past.

[weatherwiz]

There's several snow events within a few days of each analog too...you have a couple minor events (moderate where Phil is on the Cape) near that 2005 date, and of course if you roll it forward 6 days....

1971 Thanksgiving interior snowstorm is there....Dec 16, 1989 storm is there....a few other smaller events in the composite, but they certainly show that similar patterns have produced something in the past.

I feel quite confident in the upcoming pattern, it may not exactly produce right away but we should definitely get our chances.

[Damage In Tolland]

Looks like we'll kick things off with the wintry threat for the holiday and if things break right several nickel and dime events in the week to 10 days after that. My kind of pattern. Don't need the coastal bombs just nice 3-6 inchers

[nzucker]

Looks like we'll kick things off with the wintry threat for the holiday a cutterand if things break right several nickel and dime events cutters in the week to 10 days after that. My kind of pattern. Don't need the coastal bombs just nice 3-6 inchers

You got it buddy.

I actually think your area will see some decent snows in early December although I am never enthusiastic about marginal SWFE in the first days of winter. The -NAO block is trying to get something going but the Pacific is just putrid.

[ORH_wxman]

You got it buddy.

I actually think your area will see some decent snows in early December although I am never enthusiastic about marginal SWFE in the first days of winter. The -NAO block is trying to get something going but the Pacific is just putrid.

It doesn't have to be a SWFE though...could easily be a clipper type storm that is forced to redevelop south of here because of the block or some impulse rotating around the stalled vortex in SE Canada. There's multiple ways to get an event in those types of patterns as the analog dates in the first post indicated.

We don't know how the individual storm setups will look though until we are much closer.

[HoarfrostHubb]

I prefer the modified arctic air over the frigid polar air, Seems more time then not when we get the bone chilling variety we end up dry as well as storms end up getting shunted to the SE here, The signals do remain for a colder 1st part of Dec which looks to be active as well, Thats really all we can ask if the ingredients are there we should be able to get something to come together and fall in place for some Dec snows.........

I agree with this, but I have no way of figuring out if it is true or not...

[nzucker]

I agree with this, but I have no way of figuring out if it is true or not...

Not necessarily...PDII and January 1996 were huge snowstorms with brutally cold airmasses.

I think people are underestimating how cold it needs to be to snow in late November/early December. This is not the time of year to be counting on marginal airmasses.

[CoastalWx]

Not necessarily...PDII and January 1996 were huge snowstorms with brutally cold airmasses.

I think people are underestimating how cold it needs to be to snow in late November/early December. This is not the time of year to be counting on marginal airmasses.

Maybe for you and I, but the pattern def works for the interior. I'd like to see 850 temps colder than -4 for my backyard.

[Damage In Tolland]

Not necessarily...PDII and January 1996 were huge snowstorms with brutally cold airmasses.

I think people are underestimating how cold it needs to be to snow in late November/early December. This is not the time of year to be counting on marginal airmasses.

Not in a downsloping River Valley below sea level in SE NY..no it's not

[ORH_wxman]

Not necessarily...PDII and January 1996 were huge snowstorms with brutally cold airmasses.

I think people are underestimating how cold it needs to be to snow in late November/early December. This is not the time of year to be counting on marginal airmasses.

Dude, both of those snowstorms whiffed dryslot to the south and barely got far enough north here.

We don't need -12C 850s to get snow events here in late Nov or early Dec.

It may not work out, there's never any guarantees the pattern will unfold exactly how we think or the individual storms will set up the way we want, but I'm not under estimating what it takes to get a snow event around Dec 1st. I've been doing this for 7 years and know the area climo fairly well. Yes, I wouldn't feel good if I was on Cape Cod or out in a boat in Boston Harbor, but a chunk of the population may want to stay tuned for some potential in the 2 weeks following Thanksgiving.

[CoastalWx]

The 12z gfs ensembles have all sorts of storminess.

[ORH_wxman]

The 12z gfs ensembles have all sorts of storminess.

They love Dec 4-5 for a potential miller B....and there's several other nice looking setups. Very active and favorable look on the ensembles. Lets just hope that one of them can work out.

[CoastalWx]

They love Dec 4-5 for a potential miller B....and there's several other nice looking setups. Very active and favorable look on the ensembles. Lets just hope that one of them can work out.

Yeah clearly there are some warmer solutions as well. I guess we should strap in and go with the flow. I'm sure there will be some interesting up and down periods on here in the next 2 weeks.