November 2012 Observations and Discussions

[andyhb]

The OP GFS isn't worth a look in the long range, let alone the medium range. But yeah, it's pretty bad. The ensembles offer a much better look into things at that range. Seeing the Euro ensembles improve each run the last day or two has been very encouraging.

Yeah, if any OP model to look into the long(er) ranges is to be used, I'd go to the Euro and before that, the ensembles, so it's not that much of a deal at all.

[Weathergun]

0z GEFS is colder than the OP. But there is no west-based block, on the 11-15 day range:

[Snow_Miser]

06z GFS is a lot better than the 00z GFS. Develops a -NAO on the 19th of November per the Raleigh WX maps.

[FPizz]

06z GFS is a lot better than the 00z GFS. Develops a -NAO on the 19th of December per the Raleigh WX maps.

December?

[famartin]

December?

Didn't you hear? They just extended the GFS out to 2,000 hours

[earthlight]

DGEX brings it ... this storm is bookended by 10 days of high cirrus on either side.

http://www.meteo.psu.edu/~fxg1/DGEXEAST_6z/dgexloop.html

[Snow_Miser]

December?

Wow, I hadn't even realized that I had typed December. Thanks for the catch.

Anyways, the 12z GFS had a pretty robust west based NAO developing in the mid to long range:

The 12z ECMWF flipped back to showing a +NAO for almost the entire forecasting period.

[IsentropicLift]

DGEX brings it ... this storm is bookended by 10 days of high cirrus on either side.

http://www.meteo.psu...z/dgexloop.html

Nothing like 6" of rain on Thanksgiving to brighten the holiday spirits!

[IsentropicLift]

ICE...COLD...RAIN!

[NorEaster27]

looks pretty dry and uneventful for the next two weeks, a welcome break.

[IsentropicLift]

looks pretty dry and uneventful for the next two weeks, a welcome break.

Well now that you said that, expect a Hurricane followed by 30" of snow the next day.

The tail end of the 12z GFS is also churping right around the time that most people suspect that things will get interesting.

[bluewave]

That block really dominates the pattern to the point that the coastal development gets shunted out the east.

[FPizz]

Didn't you hear? They just extended the GFS out to 2,000 hours

Haha, Nice!

[Isotherm]

12Z ECMWF pretty much confirms my concern, namely that it's too early to bite on the idea of a big -NAO. We've seen this happen too many times with models -- get pulled into the D 7-10 proggs, only to have the -NAO move farther and farther into the future like a mirage in the desert. Until I see an NAO blocked progged under D 7, I'm not going to buy into it as other global indicators really aren't all that conducive for a -NAO just yet. Models tend to variate from one extreme to another in times of pattern change, and they also tend to feedback and develop a certain pattern too early. We may have a situation where we wait until the 2nd week or middle of December before we get a favorable storm pattern going. This is when climo gets good anyway, so folks shouldn't want the "snowy" pattern to initiate at Thanksgiving. Of course another option is we don't flip to the strong -NAO block at all in December. Will be very interesting to see how we evolve through late Nov.

[earthlight]

12Z ECMWF pretty much confirms my concern, namely that it's too early to bite on the idea of a big -NAO. We've seen this happen too many times with models -- get pulled into the D 7-10 proggs, only to have the -NAO move farther and farther into the future like a mirage in the desert. Until I see an NAO blocked progged under D 7, I'm not going to buy into it as other global indicators really aren't all that conducive for a -NAO just yet. Models tend to variate from one extreme to another in times of pattern change, and they also tend to feedback and develop a certain pattern too early. We may have a situation where we wait until the 2nd week or middle of December before we get a favorable storm pattern going. This is when climo gets good anyway, so folks shouldn't want the "snowy" pattern to initiate at Thanksgiving. Of course another option is we don't flip to the strong -NAO block at all in December. Will be very interesting to see how we evolve through late Nov.

Without a doubt. The models have been bouncing back and forth with what's going to happen at the higher latitudes especially in regard to the blocking. There seems to be some developing agreement for a monster Aleutian ridge and at least some positive anomalies in the Northwest Atlantic. The new GFS super ensemble now has lower heights over the pole, Greenland, and the Davis straight through Days 8-10 and beyond which will at the very least delay any excitement we might have for big time west based blocking. I am still encouraged about the potential for a major blocking event at some point this winter. But we need to watch carefully the next few weeks, which should give us an idea of whether it will occur sooner or later.

[Storm At Sea]

Model bouncing would be expected with a pattern change. It's almost a given of at least a three day period with -NAO starting around Nov. 19. The question is: what's next after that?

Without a doubt. The models have been bouncing back and forth with what's going to happen at the higher latitudes especially in regard to the blocking. There seems to be some developing agreement for a monster Aleutian ridge and at least some positive anomalies in the Northwest Atlantic. The new GFS super ensemble now has lower heights over the pole, Greenland, and the Davis straight through Days 8-10 and beyond which will at the very least delay any excitement we might have for big time west based blocking. I am still encouraged about the potential for a major blocking event at some point this winter. But we need to watch carefully the next few weeks, which should give us an idea of whether it will occur sooner or later.

[Isotherm]

Model bouncing would be expected with a pattern change. It's almost a given of at least a three day period with -NAO starting around Nov. 19. The question is: what's next after that?

What's your basis for a -NAO beginning the 19th? I see a +NAO on both the GFS and Euro valid early next week.

In fact the pattern on the ECMWF is +NAO throughout..

Edit -- looks like the GFS ensembles are in good agreement for a -NAO beginning around early next week, so there's definitely disagreement in the modelling.

[Storm At Sea]

Postive NAO this cycle has likely reached its peak today and should be decreasing over the next several days. Ensemble schemes continue to be very steadfast with a negative NAO (0 to -0.1) starting around Nov. 19-20 and gradually dropping until around the 23-24. The variability of the GFS and Euro have been quite erratic so I'm hesitant to predict the NAO based on them alone.

What's your basis for a -NAO beginning the 19th? I see a +NAO on both the GFS and Euro valid early next week.

In fact the pattern on the ECMWF is +NAO throughout, so I'd like to know where you're getting all this confidence for a -NAO developing within the next week.

[Isotherm]

Postive NAO this cycle has likely reached its peak today and should be decreasing over the next several days. Ensemble schemes continue to be very steadfast with a negative NAO (0 to -0.1) starting around Nov. 19-20 and gradually dropping until around the 23-24. The variability of the GFS and Euro have been quite erratic so I'm hesitant to predict the NAO based on them alone.

Yeah I made an edit in my last post re the ensembles being persistent w/ the -NAO idea.

Side note -- if this winter ends up being a -NAO overall, that's 4 out of the last 5 winters w/ a -NAO dominant, 08-09, 09-10, 10-11, and this one. No doubt that we've returned to the -NAO decadal phase, but the freqenecy and magnitude of blocking episodes has been extreme. The low solar constant is playing a significant role in this IMO. The next solar cycle should be even weaker than the current one, and given the state of other global indices (-PDO, declining AMO), I think we could be in for an interesting ride the next 10 years.

[earthlight]

We're definitely entering a -NAO decadal phase...there's almost no doubt left in my mind. It will be very interesting to see how things play out over the next few weeks. The last couple of winters we've had a pretty good idea what the deal will be by the third week of november. In 2010 we knew things were going to go wild by mid-December...I remember many people (you and I included) were honking about the potential late-Dec period for weeks before the event. And last year, of course, we know that by mid-november we were all well aware that we were dead in the water until the holidays at the earliest. So this year is a little different in that we have to watch carefully how things behave over the next week or two.

[nzucker]

We're definitely entering a -NAO decadal phase...there's almost no doubt left in my mind. It will be very interesting to see how things play out over the next few weeks. The last couple of winters we've had a pretty good idea what the deal will be by the third week of november. In 2010 we knew things were going to go wild by mid-December...I remember many people (you and I included) were honking about the potential late-Dec period for weeks before the event. And last year, of course, we know that by mid-november we were all well aware that we were dead in the water until the holidays at the earliest. So this year is a little different in that we have to watch carefully how things behave over the next week or two.

I think that block over Hudson Bay/SE Canada could turn into a bona fide -NAO if a low can slide underneath and bring down that cold air sitting in NW Canada/Alaska. What's virtually assured is a strong Aleutian ridge which will keep northern Canada cold. Whether we see the mechanism to bring down the cold is still in question, but temperatures look to average slightly below normal through Thanksgiving with a weakness over the Southeast coast. Whether anything more significant than a meandering cut-off in the southern stream develops is anyone's guess. But the Aleutian ridge definitely reminds me of late December and early January in Winter 10-11. We also had that favorable blocking pattern over AK in 08-09 when the NAO wasn't cooperating.

As wavelengths grow longer, the Aleutian ridge will grow more powerful in its ability to bring down cold.

[Weathergun]

Last year, around this time, we pretty much knew how December would play out. With the Euro weeklies showing the MJO, most of December, in warmer phases 2-6 in a La Nina winter:

[Storm At Sea]

So did I when I was walking around Manhattan in a suit on my way to an interview in mid 60 temps while sweating.

Last year, around this time, we pretty much knew how December would play out. With the Euro weeklies showing the MJO, most of December, in warmer phases 2-6 in a La Nina winter:

[WeatherX]

So did I when I was walking around Manhattan in a suit on my way to an interview in mid 60 temps while sweating.

Uncomfortable itching in the crotch area? Man pads-check them out......

[Storm At Sea]

I believe that I'm the physician in this forum...you didn't get the memo?

Uncomfortable itching in the crotch area? Man pads-check them out......

[earthlight]

I think that block over Hudson Bay/SE Canada could turn into a bona fide -NAO if a low can slide underneath and bring down that cold air sitting in NW Canada/Alaska. What's virtually assured is a strong Aleutian ridge which will keep northern Canada cold. Whether we see the mechanism to bring down the cold is still in question, but temperatures look to average slightly below normal through Thanksgiving with a weakness over the Southeast coast. Whether anything more significant than a meandering cut-off in the southern stream develops is anyone's guess. But the Aleutian ridge definitely reminds me of late December and early January in Winter 10-11. We also had that favorable blocking pattern over AK in 08-09 when the NAO wasn't cooperating.

As wavelengths grow longer, the Aleutian ridge will grow more powerful in its ability to bring down cold.

The GFS Superensemble is going through the roof with the Aleutian ridge which is certainly not a bad sign moving forward. There are plenty of people starting to get concerned over the GOA vortex, but it needs to be stressed that that feature is a trough as a result of the big Aleutian ridge, and is actually pretty far south and east...so much so that in an amplified pattern it could cause a big west coast ridge between the Pac NW and Boise that pushes up into British Columbia.

When you start talking about Hudson Bay//West Based -NAO blocking with a huge Aleutian ridge...you start talking big cold and potential storminess.

[Neblizzard]

The GFS Superensemble is going through the roof with the Aleutian ridge which is certainly not a bad sign moving forward. There are plenty of people starting to get concerned over the GOA vortex, but it needs to be stressed that that feature is a trough as a result of the big Aleutian ridge, and is actually pretty far south and east...so much so that in an amplified pattern it could cause a big west coast ridge between the Pac NW and Boise that pushes up into British Columbia.

When you start talking about Hudson Bay//West Based -NAO blocking with a huge Aleutian ridge...you start talking big cold and potential storminess.

[Neblizzard]

John is it better to have a massive Aleutian Ridge or low? I always thought an Aleutian Low Teleconnects to a ridge over the West Coast (+PNA)

[andyhb]

John is it better to have a massive Aleutian Ridge or low? I always thought an Aleutian Low Teleconnects to a ridge over the West Coast (+PNA)

The persistent Bering Sea/Strait Vortex was one of the main reasons why last winter was...let's just say...sub-par.

[Stormlover74]

At the halfway mark EWR is a full 4.0 degrees below normal. Will be quite difficult to get this month at or above normal (barring some kind of 3-4 day torch)