Pattern Discussion 12/15 and beyond

[CoastalWx]

This is the Chris storm and he is too modest to credit for seeing this potential. But anyway, I agree there is a threat then. If there is going to be a good storm, it is going to be when the NAO signal fades westward with split flow underneath. You still got to favor New England with this setup, given the teleconnections. If the NAO-west idea becomes legitimate, then perhaps the northern Mid Atlantic will be snowier than I thought.

But I'm still not feeling a west-based NAO yet so I think this ultimately is for you guys.

Yeah he pointed that potential out. I find that feature interesting, but it's there even on the EC which is weakest and most realistic it seems, with the -NAO. Of course those SW plains storms would be a lot more interesting with a -NAO. OV track turns into EC redeveloper. My guess is the more east based look which may feature a thumb ridging knifing in from eastern Greenland. Intensity TBD, but I think it will be there.

[HM]

Bumped from other thread.

It's a good question. I suppose the the warm 30mb temperatures mean a few things:

1. The coldest portion of the tropopause / lower stratosphere is between 150-50mb and rapidly you move into the stratified layer where cross-gradient shear develops, like when you have a +QBO. This enhanced jet could weaken convective areas that are not part of stagnant, walker forcing.

2. The warmer the mid stratosphere, the weaker the uplift process from transitioning water vapor into ozone. This also means weaker subsidence in the Subtropics, possibly aiding in the strong East-Asian Jet. This feedbacks onto the Tropics, limiting forcing to walker cells (-AAM tendency).

3. Internal gravity waves will dominate between walker cells and this too would be a positive feedback against the MJO. The warming aloft and relative warming at 50mb (remember that stratospheric equatorial temperatures bias cooler than normal due to climate change) aid in the subsidence cells of the Walker.

So to sum up...unless you got a good reason to have convection....the stratosphere says no (i.e. Walker Cells and their internal waves).

Hope this helped, my friend.

[CoastalWx]

Thanks man, I was just curious, but you make a good point about the potential temp bias. Perhaps 50mb is warmer than we are led to believe which leads into those factors you mentioned.

[ORH_wxman]

Its still present, AK has been in the freezer for the past couple weeks

http://newsminer.com...ndow_left_top_1

AK can be cold without a death vortex...December 2010 was the coldest December in Fairbanks in 30 years. If the low heights are along the eastern edge of AK and into W Canada...that is not the same as a death vortex sitting over AK/Bering straight. The former is a pattern seen with a poleward aleutian ridge frequently. December 1975 was another frigid Fairbanks December.

The heights havent even beeb below normal in Fairbanks in Nov and first part of Dec here...they have just been on the east side of the ridge which produces cross polar flow.

[leo1000]

Its crazy that the polar vortex keeps coming back so quickly. Where is the sst warming event that will destroy this vortex once and for all?.

[CoastalWx]

If you look at things like GWO, it does support a more -PNA pattern. Don't read into it as anything more than that..lol. Perhaps if we can get the MJO to look like what the EC ensembles have, we can get another burst into the Nino sectors of the diagram.

[HM]

Thanks man, I was just curious, but you make a good point about the potential temp bias. Perhaps 50mb is warmer than we are led to believe which leads into those factors you mentioned.

Yeah you can tell from the CPC maps that the coldest portions are right over walker uplift /convection and where the water vapor flux is highest.

But remember, this all speculation and theory. The cross-tropopause shear involved with +QBO events is valid per research but I'm speculating that currently 30mb is behaving like that due to the temperatures (despite wind).

When Walker Cells are strong, internal waves rule and the MJO usually goes to sleep as everything becomes stagnant.

[Typhoon Tip]

I don't know what you folks are all looking at without reading all these post but that's a truly massive signal between the 15th and 20th - f aw-hasome

[WilkesboroDude]

We've been discussing the pattern with some greay insight from many posters in the general banter thread...but the posts get buried quickly so I decided to start this thread where we can post some thoughts and it will be easier for people to find the posts:

[Jersey Andrew]

Hey Tip, I went back to read your spectacular post from December 5, 2010 that forewarned of the impending winter fun in store. Are you seeing similarities in pattern development this year? What factors are causing you to have such a positive outlook for second half of December?

[ORH_wxman]

I don't know what you folks are all looking at without reading all these post but that's a truly massive signal between the 15th and 20th - f aw-hasome

Scott and I were talking about it earlier on the phone....but in caution of getting weenies too riled up, I haven't said anything really...same with Scott. But there is definitely something fishy in that time frame where we could get a good event. Given it is still 10-14 days out, hard to get too bullish.

I told him that week leading up to Christmas looked like December 1970. Of course, it may not materialize like the models show and the same pattern doesn't have to produce great snow....but those are odds you would certainly put in your pocket.

[HM]

I don't know what you folks are all looking at without reading all these post but that's a truly massive signal between the 15th and 20th - f aw-hasome

About a month ago or a little less, Chris and I developed ideas for -NAO blocking developing 12/5-10 and finishing up toward the 20th. While the first part didn't quite work out the way I wanted it to, the second part still has a chance. Chris speculated then that perhaps 12/18-20 or so was the main time frame to watch. As we inch closer, I think he may be right. The only thing preventing me from doing the "usual" is that I'm worried that the stratosphere isn't enough or the tropical forcing. However, those two things can easily change by then to allow for this signal.

On a completely timing related note, the wave behavior may be similar to 2009-10. It is unfortunate that the waves in the Tropics and Stratosphere are weaker.

The cold vortex and disturbed vortex periods that winter may be similar in timing to this winter, even if the results are different.

[Amped]

ORHwxman was looking for something to flatten heights over the Candian Maritimes last week. GFS ensembles show exactly that starting Day7.

SHould be a sharp cutoff with the lack of a PNA. Hard to say where it will be, only safe bet is that DC and Philly will be screwed.

[ORH_wxman]

ORHwxman was looking for something to flatten heights over the Candian Maritimes last week. GFS ensembles show exactly that starting Day7.

SHould be a sharp cutoff with the lack of a PNA. Hard to say where it will be, only safe bet is that DC and Philly will be screwed.

The NAO is what should help that. Dec 1970 had low anomalies there too with an east based -NAO. 2007 had it but in the form of an obnoxiously large vortex in the southern Davis Straight...it was so big that it crushed all the heights into Novia Scotia/New Foundland....one example of a "good" +NAO....but it really acts like a -NAO further north.

[toronto blizzard]

Based on the weeklies for weeks 3&4 they have a -PNA and SE ridge pattern which would develop a la nina gradient pattern. Based on the weeklies how does temp and precip do around here?

[ORH_wxman]

Based on the weeklies for weeks 3&4 they have a -PNA and SE ridge pattern which would develop a la nina gradient pattern. Based on the weeklies how does temp and precip do around here?

Week 4 was a suicide pattern...massive ridge over the east...but week 4 is essentially just fodder and only that. It changes all the time.

[CoastalWx]

Week 4 was a suicide pattern...massive ridge over the east...but week 4 is essentially just fodder and only that. It changes all the time.

He's already going up the elevator in the CN tower.

[OceanStWx]

He's already going up the elevator in the CN tower.

The latest NHL lockout news can't be helping either.

At this point Leaf fans might be flapping in the wind, hanging by their Sudin sweaters.

[Typhoon Tip]

Hey Tip, I went back to read your spectacular post from December 5, 2010 that forewarned of the impending winter fun in store. Are you seeing similarities in pattern development this year? What factors are causing you to have such a positive outlook for second half of December?

If I recall ...not quite similar. That late November/early Dec saw changes at high latitudes of the Asian/N Pacific relay taking place at just about the same time the MJO was about to crank into late phase 7 - the result of a powerful EPO ridge and huge cold loading into the Canadian shield was warranted - then the NAO was step wise forecast to tank some 1 week later. It was about as close to a slam dunk hurry up and wait for the tsunamis as you can get in this business. I think I used a lot of teleconnector annotations for that, but a lot of it was simply real time observations combined.

Here, the signal is almost entirely AO/NAO reliant. We are also is sort of hurry up and wait.

There is another aspect to this, and that is that there is a lot of cold air around. The current air mass is overperformed, and I suspect the one behind the 72 hour system will also be, and set stage for what I believe is likely to be an icy mess as that polar high wedges in overrunning ensues.

[Typhoon Tip]

Scott and I were talking about it earlier on the phone....but in caution of getting weenies too riled up, I haven't said anything really...same with Scott. But there is definitely something fishy in that time frame where we could get a good event. Given it is still 10-14 days out, hard to get too bullish.

I told him that week leading up to Christmas looked like December 1970. Of course, it may not materialize like the models show and the same pattern doesn't have to produce great snow....but those are odds you would certainly put in your pocket.

Yeah I was holding back some, but I saw your thread here and figured you guys cutting out the bullcrap by having analysis only.

It has to do with piling up the wave spacing from the N Atlantic backward in the flow. This quasi negative PNA jet has to go somewhere, and it breaks into a giant deep vortex (potentially) and quite close to our lat/lon.

It's a mammoth signal, yeah, but that doesn't say anything about a confidence interval - haha

[michsnowfreak]

Scott and I were talking about it earlier on the phone....but in caution of getting weenies too riled up, I haven't said anything really...same with Scott. But there is definitely something fishy in that time frame where we could get a good event. Given it is still 10-14 days out, hard to get too bullish.

For the last few days, several gfs ensembles have hinted at a major winter storm/blizzard hitting the midwest or northeast in the Dec 17-20 timeframe. Obviously anything far out is literally a fantasy, but its just interesting that each run has had at least a few ensembles point towards such a nice storm.

The weeklies look cold through New Years per Harry, which is great as long as some snow comes. Anytime a cold airmass is in place clippers are a distinct possibility, but as for bigger storms, any thoughts on storminess (or lack of?) in the eastern Lakes with this pattern? Sometimes we seem to get affected by the same storms as ne, other times (noreasters) not.

[NJwinter23]

This is the Chris storm and he is too modest to credit for seeing this potential. But anyway, I agree there is a threat then. If there is going to be a good storm, it is going to be when the NAO signal fades westward with split flow underneath. You still got to favor New England with this setup, given the teleconnections. If the NAO-west idea becomes legitimate, then perhaps the northern Mid Atlantic will be snowier than I thought.

But I'm still not feeling a west-based NAO yet so I think this ultimately is for you guys.

Lol hey I appreciate the praise, but i tend to think this threat materializing was more luck in the end, since the pattern isnt progressing quite how I imagined it when first mention of an 18th-20th threat.

[Typhoon Tip]

About a month ago or a little less, Chris and I developed ideas for -NAO blocking developing 12/5-10 and finishing up toward the 20th. While the first part didn't quite work out the way I wanted it to, the second part still has a chance. Chris speculated then that perhaps 12/18-20 or so was the main time frame to watch. As we inch closer, I think he may be right. The only thing preventing me from doing the "usual" is that I'm worried that the stratosphere isn't enough or the tropical forcing. However, those two things can easily change by then to allow for this signal.

On a completely timing related note, the wave behavior may be similar to 2009-10. It is unfortunate that the waves in the Tropics and Stratosphere are weaker.

The cold vortex and disturbed vortex periods that winter may be similar in timing to this winter, even if the results are different.

Interesting ... perhaps we come to the same conclusion, but differently.

By the way folks, -4 AO on deck, and with the NAO trying to drill west across the D. Straight, that is precisely what you want to see prior to a major arctic outbreak on THIS side of the hemisphere.

[ORH_wxman]

For the last few days, several gfs ensembles have hinted at a major winter storm/blizzard hitting the midwest or northeast in the Dec 17-20 timeframe. Obviously anything far out is literally a fantasy, but its just interesting that each run has had at least a few ensembles point towards such a nice storm.

The weeklies look cold through New Years per Harry, which is great as long as some snow comes. Anytime a cold airmass is in place clippers are a distinct possibility, but as for bigger storms, any thoughts on storminess (or lack of?) in the eastern Lakes with this pattern? Sometimes we seem to get affected by the same storms as ne, other times (noreasters) not.

Well if the pattern shakes out like the ensembles want it to...then we'd probably share a lot of the same storms. A Great Lakes to New England pattern is exactly what is favored. It does not look like a favorable pattern for Nor' Easters unless it redeveloped pretty late which is always possible, but not probable.

OH Valley runners would want to be the main storm track. But we are still a ways out and obviously the usual caveats are in place. Don't expect epic snow at this range....but make a note that the 12/16-12/25 period could be pretty interesting and hope it stays that way.

[Ginx snewx]

Can not deny the AO. Looking better every day. But don't want to get the Mets riled up so keep it on the low.

[michsnowfreak]

Well if the pattern shakes out like the ensembles want it to...then we'd probably share a lot of the same storms. A Great Lakes to New England pattern is exactly what is favored. It does not look like a favorable pattern for Nor' Easters unless it redeveloped pretty late which is always possible, but not probable.

OH Valley runners would want to be the main storm track. But we are still a ways out and obviously the usual caveats are in place. Don't expect epic snow at this range....but make a note that the 12/16-12/25 period could be pretty interesting and hope it stays that way.

I notice many of the periods you guys talk about as being awesome were awesome here as well, but a few others you guys rave about absolutely sucked here (snow-wise), and in those instances I can always connect it to a noreaster (rather than a cutter, runner, etc). You guys are always talking 1968-69...that is the last time Detroit saw under 20" in a winter (just 17.1" that season ). But then a lot of the other years you guys talk about were pure bliss here too.

Im on vacation Dec 14-25...I could not draw up a more perfect scenario than the 12/16-25 period, so I will DEFINITELY hope it stays that way. And Im fine without epic snow. I look at it like this...we have the next 4.5 months to get big snowstorms. Just give me snow for Christmas/Christmas season and Ill be happy. Once the busy schedules of the holidays cease, winter is a much slower pace of life, so THATS the time to worry about big snowstorms. And I actually have a feeling that maybe this WILL be the year to get a massive storm here, because we just went through our snowiest - in fact by far our snowiest - 4-year period on record at Detroit (2007-08 thru 2010-11) with no storm bigger than 10.3", just a ton of 6-10" storms. I said after the wonderful 2010-11 winter that within 3 years we would get that massive storm and it would come in a winter thats not necessarily that impressive in terms of seasonal total. So I have 2 more years to make it happen .

[Typhoon Tip]

Well if the pattern shakes out like the ensembles want it to...then we'd probably share a lot of the same storms. A Great Lakes to New England pattern is exactly what is favored. It does not look like a favorable pattern for Nor' Easters unless it redeveloped pretty late which is always possible, but not probable.

OH Valley runners would want to be the main storm track. But we are still a ways out and obviously the usual caveats are in place. Don't expect epic snow at this range....but make a note that the 12/16-12/25 period could be pretty interesting and hope it stays that way.

I have one problem with this sort of thinking though, and that storm tracks west of NE are not well correlated with -NAO, particularly when the NAO block flavors west. The NAO back drills the flow lower in latitude, often times to forecaster chagrin, too, because the models don't see that, and consummately will butt heads with it in late middle range/extended visions, only to capitulate eventually. Miller B in there perhaps

We'll have to see if that transpires, but it is possible to ledge up a slow moving cut-off sort of scenario with flattish west structure, and the west-based NAO is paramount in getting that to happen. Check Kocin/Ucellini

[Typhoon Tip]

Can not deny the AO. Looking better every day. But don't want to get the Mets riled up so keep it on the low.

Lol - good one!

[ORH_wxman]

I have one problem with this sort of thinking though, and that storm tracks west of NE are not well correlated with -NAO, particularly when the NAO block flavors west. The NAO back drills the flow lower in latitude, often times to forecaster chagrin, too, because the models don't see that, and consummately will but heads with it in late middle range/extended visions, only to capitulate eventually.

We'll have to see if that transpires, but it is possible to ledge up a slow moving cut-off sort of scenario with flattish west structure, and the west-based NAO is paramount in getting that to happen. Check Kocin/Ucellini

Well I wasn;t implying that the storms would be cutting up into Ottawa...but OH Valley runners are common in a -NAO if the PNA is negative...they just often redevelop south of us and scoot east....not a "Nor Easter" per say...but sfc pressure getting squeezed south of us ala 12/13/07, 12/19/08, 12/20/70, etc....an overrunning storm that may "normally" be a cutter, but it gets stuffed going in for the layup and pushed east by the low height anomaly to our northeast induced by the -NAO. (or in the case of the 2007 systems...the "pseudo -NAO" which was really just a massive west based +NAO so big that it caused low heights north of Maine)

[OSUmetstud]

Its still present, AK has been in the freezer for the past couple weeks

http://newsminer.com...ndow_left_top_1

cold ak is not the same as an Ak vortex