Where we're at, where we're going

[HM]

Do you think the Atlantic blocking is finally going to overcome the poor Pacific to produce a coastal or redeveloping SWFE, HM?

Also, do you feel the NAO is retrograding too far west which is allowing that 50/50 low to move towards the Plains and phase more energy into a potential lakes cutter?

I always liked this period for a solid -NAO and I am glad to see it come to fruition. The -EPO jump-started it and it appears to be a nice battle shaping up. Ultimately, I think this -NAO anomaly retrogrades and this is always a good thing for the East. Models like to alleviate these bubbles any way they can by making continental ridges or simply deamplifying it. Usually, it comes out cold/snowy when they retrograde and sometimes historically snowy.

Imagine a high-frequency wave pattern from the Pacific forced south under a block! What a stormy pattern!

[Ender]

I decided to look at the ncep superensemble mean to see what analogs it spits out. It is a centered mean that covers 5 days and today's prog is centered on November 30th. One of the advantages at looking at a centered mean is that it damps out the shorter less predictable waves and the larger scale waves show up giving and idea of what overall pattern might be in terms of temps, etc but it can't tell you which days will be the coldest or even whether there might be a warm day sandwiched into the period. Last year the product really helped identify possible "windows of opportunity" for snow and really suggestIed that the pattern was one in which the odds of a major snowstorm/s was way above climo.

Where's the NCEP mean map? I've been using the CPC D+8 analogs.

FWIW, they show:

11/19/65: No real snowfall until well into January. Decent winter otherwise. (just thought it'd be an interesting bit of trivia)

11/29/50: 1.6" fell 4dy prior to the analog date, 3.2" fell on 12/10-11. Awful winter.

12/08/81: 1." on 12/14, 1.2" on 12/15 and .4" on 12/16. Decent winter, though...

11/12/63: No snow for at least a month. Great winter.

12/03/54: .1" fell two days later. Horrible winter.

11/24/50: 1.6" the next day...3.2" about 2wk later as above.

11/17/73: It took a month before we saw snow. Not a complete disaster of a winter, tho.

11/17/51: Almost a month until we saw snow. Not all that great a winter.

11/28/54

11/11/90: First snow 1mo later. Abysmal winter.

So...at least one of the more favored analogs had snow about 10 - 15 days later.

[usedtobe]

Where's the NCEP mean map? I've been using the CPC D+8 analogs.

FWIW, they show:

11/19/65: No real snowfall until well into January. Decent winter otherwise. (just thought it'd be an interesting bit of trivia)

11/29/50: 1.6" fell 4dy prior to the analog date, 3.2" fell on 12/10-11. Awful winter.

12/08/81: 1." on 12/14, 1.2" on 12/15 and .4" on 12/16. Decent winter, though...

11/12/63: No snow for at least a month. Great winter.

12/03/54: .1" fell two days later. Horrible winter.

11/24/50: 1.6" the next day...3.2" about 2wk later as above.

11/17/73: It took a month before we saw snow. Not a complete disaster of a winter, tho.

11/17/51: Almost a month until we saw snow. Not all that great a winter.

11/28/54

11/11/90: First snow 1mo later. Abysmal winter.

So...at least one of the more favored analogs had snow about 10 - 15 days later.

Ncep and CPC are the same animal but i used the D+11 instead of the d+8. If I did right. late Nov 1971, early 2005 and late 1950 all had at least and inch at dca. It's interesting that the two products, 3 days apart gave different years. Unless the ensembles are in pretty good agreement like last year, looking at them is more fun than educational.

[Dr No]

Never underestimate the power of 12/5 gents!

Would that make 7 out of the last 10 DC Metro measured snow in the 12/5-12/7 timeframe?

[Feb]

Never underestimate the power of 12/5 gents!

Would that make 7 out of the last 10 DC Metro measured snow in the 12/5-12/7 timeframe?

Even more amazing is two straight runs of the GFS show this.

[WinterWxLuvr]

Never underestimate the power of 12/5 gents!

Would that make 7 out of the last 10 DC Metro measured snow in the 12/5-12/7 timeframe?

Cool thing about that is the 12z was showing the same thing, maybe even a little better. Bad thing is I need 12/2 for the first snow contest.

Here's where I wish we had the ask a pro section. I distinctly remember last November very early in the month, the models started showing a dramatic change to cold that kept getting pushed back and back and back. Then it finally showed a decent cold shot around Thanksgiving which turned out to be about a one day cold shot. On the Sunday after Thanksgiving here in Winchester it was in the low 60's and the next Sunday, I was shoveling my driveway. I don't know anything about how the pattern this year relates to last year's, but there's some deja vu feeling here. I wonder how this advertised cool down will play out, and what will follow it.

Edit: I see Feb beat me to it.

[Alpha5]

Both beyond 240 hours, I wouldn't put too much stock into them. I suspect that they may be gone by the 18Z run but could always show up again on a later run.

http://www.americanw...40-the-pattern/

There both there on the 18z

Too bad the Euro looks nothing like the GFS at day 10

[atownwxwatcher]

Only problem is verbatim this would not be a snow event...

Not that details like that matter at this time..the important thing is the storm is still there....

[tombo82685]

There both there on the 18z

Too bad the Euro looks nothing like the GFS at day 10

i think its all what hm said. You can see the gfs really develops the 50/50 low and traps it under the block, while the euro doesn't

[HM]

Only problem is verbatim this would not be a snow event...

Not that details like that matter at this time..the important thing is the storm is still there....

2m-temps at day 2 are useless. The solution, verbatim, is actually a snowstorm. The flow is mainly N/W at lower levels and there is a beautiful 50/50 in place. But like you said, this stuff doesn't matter now...just that we have something to watch. I would feel more comfortable if the ECMWF took on a more classic look, too. A hybrid scenario or not-so-classic setup may become more likely if these two models keep opposing one another.

[HM]

i think its all what hm said. You can see the gfs really develops the 50/50 low and traps it under the block, while the euro doesn't

Exactly. Not only does the PV have to get to that position but it has to stay a formidable force. It cannot weaken because then the upstream ridge from the developing wave can easily knock it out of place. It is either GFS or a big mess.

[HM]

2m-temps at day 2 are useless. The solution, verbatim, is actually a snowstorm. The flow is mainly N/W at lower levels and there is a beautiful 50/50 in place. But like you said, this stuff doesn't matter now...just that we have something to watch. I would feel more comfortable if the ECMWF took on a more classic look, too. A hybrid scenario or not-so-classic setup may become more likely if these two models keep opposing one another.

Although, I can see why you said it with the improper track of the 850mb low. But, I would have to imagine that it wouldn't track like that with the scenario the GFS is painting in the upper levels. Then again, it is a lousy La Niña winter and this is the type of thing that happens to screw you (just when you thought it was looking good).

[Ji]

Crazy blocking on 00z Gfs tonight. New CFS says below normal cold dec-feb

[MJO812]

Crazy blocking on 00z Gfs tonight. New CFS says below normal cold dec-feb

Yep. It shows below normal temps in the east and above normal temps in the west.

[Ellinwood]

Interesting to see the GFS put in the East Coast Dec. 5 storm/Nor'easter somewhat consistently over the last 3 runs. It must know the rule-of-thumb for the Mid-Atlantic

[tombo82685]

0z euro looks like it trended more towards the gfs in developing a stronger 50/50 low that gets stuck under the block keeping the northern mid atlantic and northeast cold. The only problem is, well what it looks to me is a -pna in response to a goa low. Which is not allowing the deep trof the gfs has.

[tombo82685]

0z euro might have the most epic block that i have seen so far. The block day 9-10 centered over baffin island. Only problem is still the pacific with the -pna and goa low

[tombo82685]

Post day 10 looks interesting with a storm coming out of the midwest. Not sure where it would go though, because its got a good amount of ridging out ahead of it, but the block is squashing that also.

[nzucker]

Post day 10 looks interesting with a storm coming out of the midwest. Not sure where it would go though, because its got a good amount of ridging out ahead of it, but the block is squashing that also.

Yeah it's going to be a close call for New England and maybe the Northern Mid Atlantic...there's a 50/50 moving into place with a strong west-based -NAO, but the Pacific is just god awful and trying to raise heights across the East. 0z ECM definitely isn't a disaster although not a great pattern with the monster +EPO/-NAO.

[Road Runner]

Interesting to see the GFS put in the East Coast Dec. 5 storm/Nor'easter somewhat consistently over the last 3 runs. It must know the rule-of-thumb for the Mid-Atlantic

I am highly confident that the next pattern is much easier to forecast and what you are referring to is not the actual nor'easter potential. That is the pattern changer. The nor'easter potential is most likely near or on December 11th, 2010. Keep watching. Nevertheless, it is an active pattern for nor'easters and the pattern does have plenty of cold air to boot (with similarities to Nov 27th-Dec 11th 2008). This next one might be exciting for sure!

[NJwinter23]

This looks like a fun pattern for the models to try and forecast lol.

[Alpha5]

This looks like a fun pattern for the models to try and forecast lol.

Either the GFS or the Euro is going to bust really bad...

[Ellinwood]

I am highly confident that the next pattern is much easier to forecast and what you are referring to is not the actual nor'easter potential. That is the pattern changer. The nor'easter potential is most likely near or on December 11th, 2010. Keep watching. Nevertheless, it is an active pattern for nor'easters and the pattern does have plenty of cold air to boot (with similarities to Nov 27th-Dec 11th 2008). This next one might be exciting for sure!

1) Gray?

2) Oh God that terminology again! Is the "Nor'easter potential is most likely" part just part of your theory, or do you have other evidence of it being better on Dec. 11th?

[Yeoman]

2) Oh God that terminology again! Is the "Nor'easter potential is most likely" part just part of your theory, or do you have other evidence of it being better on Dec. 11th?

It's based on the number of toes he counted on his feet.

[tombo82685]

looks like the gfs has lost the 50/50 low, hence the warm up after a transient shot of cold air after t giving.

[Dr No]

Even the GFS ensemble members are pretty diverse for the handling of the Thurs-Friday storm and front.... not surprising the great flips and flops after that time frame.

[HM]

Just when the GFS loses it, the ECMWF jumps on it. The blocking that retrogrades out of Greenland on the 12z ECMWF is jaw-dropping. It is the type of anomaly where "anything goes" as far as storm potential and phasing.

It almost looks like the Heather A. signal at 240h with a complete retrogression. Seems fast again, but hey...I'm glad the ECMWF is on board.

[Ellinwood]

BRB buying a dart board and using it for >120h

[usedtobe]

Just when the GFS loses it, the ECMWF jumps on it. The blocking that retrogrades out of Greenland on the 12z ECMWF is jaw-dropping. It is the type of anomaly where "anything goes" as far as storm potential and phasing.

It almost looks like the Heather A. signal at 240h with a complete retrogression. Seems fast again, but hey...I'm glad the ECMWF is on board.

Still, even with that, we have to wait until after the 240 hour when the vortex shifts east a little before we have much hope of anything at your or my latitudes but then climo in late nov and early dec is pretty dsimal anyway except for dec 5th during recent years.

[HM]

Still, even with that, we have to wait until after the 240 hour when the vortex shifts east a little before we have much hope of anything at your or my latitudes but then climo in late nov and early dec is pretty dsimal anyway except for dec 5th during recent years.

That's true. There may be one more storm that ends up the H.A. signal around December 5th with the 240h storm acting as a 50-50 low.

Too bad this pattern won't happen even a month later.