The Winter 2010-11 NYC/PHL Medium Range Thread

[JBG]

Yeah, thats what I figured lol-- when you have a large body of water just to your west, you are usually screwed, because you have more of a maritime climate (because weather usually moves west to east.) With a whole continent to our west, we are colder.

Ditto the Sakhalin Peninsula off Russia's east coast.

[Rainshadow]

This is why Im wondering why everyone is talking about a amazingly negative nao and such strong blocking like we had last year-- and yet storms are still cutting?

That's because the ridging on average has been farther to the east or southeast and we don't have the record breaking -ao of last winter. The pacific hasn't been that co-operative either. I can't post the image for some reason, but the 500mb positive anomaly was right over Davis Strait last winter.

[Rainshadow]

It still looks like the players are holding their ground, after next week's cold shot, if we don't start modifying after December 17th, the NAO wins, if we do the MJO/EPO/PNA win. This is working on the assumption that both oceanic teleconnection indice outlooks are correct. Just took a look at the GWO for the first time in a long time, it still is in the circle of death.

[usedtobe]

That's because the ridging on average has been farther to the east or southeast and we don't have the record breaking -ao of last winter. The pacific hasn't been that co-operative either. I can't post the image for some reason, but the 500mb positive anomaly was right over Davis Strait last winter.

It was and we also tended to have a pna pattern along with the negative ao and nao. This year, the block is too fart south and east. There also has been no real southern stream which we had last year and which is usually needed for a miller a type storm.

[Rainshadow]

It was and we also tended to have a pna pattern along with the negative ao and nao. This year, the block is too fart south and east. There also has been no real southern stream which we had last year and which is usually needed for a miller a type storm.

Wes,

Thanks forgot about that part, that is one thing that the current mdt/stg nina has not failed to do.

[nzucker]

It still looks like the players are holding their ground, after next week's cold shot, if we don't start modifying after December 17th, the NAO wins, if we do the MJO/EPO/PNA win. This is working on the assumption that both oceanic teleconnection indice outlooks are correct. Just took a look at the GWO for the first time in a long time, it still is in the circle of death.

6z GFS starts developing an AK block around Day 8, so we might see some positive changes in the Pacific eventually with a shift away from the +EPO regime we've had. That might help establish some split flow in the polar jet if the AK block can set up far enough East.

Despite all the cold air on the map early this winter, it's going to be hard for the cities to get snow with the lack of a STJ and the GOA low injecting shortwaves too far north into the CONUS; the storm track is really terrible for I-95, and will probably stay that way, until a more neutral PNA or -EPO block develops.

[Analog96]

6z GFS starts developing an AK block around Day 8, so we might see some positive changes in the Pacific eventually with a shift away from the +EPO regime we've had. That might help establish some split flow in the polar jet if the AK block can set up far enough East.

Despite all the cold air on the map early this winter, it's going to be hard for the cities to get snow with the lack of a STJ and the GOA low injecting shortwaves too far north into the CONUS; the storm track is really terrible for I-95, and will probably stay that way, until a more neutral PNA or -EPO block develops.

What we could use right now is a strong clipper.

[nzucker]

What we could use right now is a strong clipper.

Yeah hopefully we'll get one around Day 8/9 if the ridge starts pumping into the west with polar jet energy rushing down the backside of the PNA/EPO block. This would be a nice pattern for Miller B redevelopment with the strong NAO blocking showing up in the longer range modeling.

[JBG]

It was and we also tended to have a pna pattern along with the negative ao and nao. This year, the block is too fart south and east. There also has been no real southern stream which we had last year and which is usually needed for a miller a type storm.

How often do you get a Miller A in a moderate-to-strong Niña?

[Chris L]

How often do you get a Miller A in a moderate-to-strong Niña?

February 2006 is an example...

[JBG]

February 2006 is an example...

Wasn't that either a weak Niña or neutral-negative, similar to the February 1967 storm that the February 2006 storm so closely resembled?

[nzucker]

Wasn't that either a weak Niña or neutral-negative, similar to the February 1967 storm that the February 2006 storm so closely resembled?

Yeah it was very weak, basically a neutral winter. Not like this season at all.

[Rainshadow]

Wasn't that either a weak Niña or neutral-negative, similar to the February 1967 storm that the February 2006 storm so closely resembled?

Not that it can't happen, just the chances are lower as you stated. Weather & Forecasting October 2003 paper about it, its not just about NYC & PHL its a general lower incidence of KU type storms in La Nina winters. The last time PHL had a > 10" single snowfall event in a mdt/stg la nina winter was December 1909. Admittedly January 2000 came close.

[Rainshadow]

Just looking at the ensemble solutions, the fcst collapse of the -wpo opens up the Pacific Jet. Most of the MJO outlooks collapse it too soon other than the Brazilian Centre for Time and Climate Studies which at least makes the latter logically consistent. The -nao "is suppose to" die a slow death over Canada. I'm waiting on that one. Wes is much better at this than I am, the former would still force some cold air into the Conus with what still looks like a +epo don't know how south we get in trouble with this in spite of the configuration above.

[earthlight]

[am19psu]

Just looking at the ensemble solutions, the fcst collapse of the -wpo opens up the Pacific Jet. Most of the MJO outlooks collapse it too soon other than the Brazilian Centre for Time and Climate Studies which at least makes the latter logically consistent. The -nao "is suppose to" die a slow death over Canada. I'm waiting on that one. Wes is much better at this than I am, the former would still force some cold air into the Conus with what still looks like a +epo don't know how south we get in trouble with this in spite of the configuration above.

I keep waiting and waiting for the tropical forcing to win. It's why I've been quiet all week, because I can't figure out "why" the MJO hasn't exerted more of an influence. I keep hoping you or Wes or HM will enlighten me

Roundy's stuff suggests we'll go to Phase 6 by next weekend or so, which is still a fairly warm phase for the east, but I'm not holding my breath.

[Rainshadow]

I keep waiting and waiting for the tropical forcing to win. It's why I've been quiet all week, because I can't figure out "why" the MJO hasn't exerted more of an influence. I keep hoping you or Wes or HM will enlighten me

Roundy's stuff suggests we'll go to Phase 6 by next weekend or so, which is still a fairly warm phase for the east, but I'm not holding my breath.

I keep on waiting for Wes or HM to enlighten me also. Yeah can't see next week "averaging" warm, the cold shot might get truncated somewhat, I wouldn't go that far either. I thought Matt from MDA once posted for the MJO to be an effective force of change it has to rotate through phase 8/1 from where it is now. The same may be true for initiating a warm phase, probably can't just come out of the circle of death. 12/17 is the calendar day I estimated for a change, so if its still cold that weekend, the props would go to the NAO for holding the Pacific at bay.

[tombo82685]

I keep on waiting for Wes or HM to enlighten me also. Yeah can't see next week "averaging" warm, the cold shot might get truncated somewhat, I wouldn't go that far either. I thought Matt from MDA once posted for the MJO to be an effective force of change it has to rotate through phase 8/1 from where it is now. The same may be true for initiating a warm phase, probably can't just come out of the circle of death. 12/17 is the calendar day I estimated for a change, so if its still cold that weekend, the props would go to the NAO for holding the Pacific at bay.

tony what does it mean when the mjo is in the circle of death? Is it that its not the dominating teleconnector and other teleconnectors take over?

[SnowGoose69]

How often do you get a Miller A in a moderate-to-strong Niña?

2/11/06 and 3/15/99 are the the only examples I can think of as Chris L said....2/1989 was sort of a Miller A as was 1/2000 but both of those lows sort of formed more so off the the SC/GA coast so they were not really true Miller As if you ask me...just far south forming Miller Bs....if its gonna happen its comes late in the season generally....the southern Plains region generally is a good area to key in on for southern stream action since all of their winter weather events in southern KS and MO, all of OK, AR, and N TX are generally induced that way, hence why 87/88, 72-73 and 09/10 are in those regions top 5 snowiest winters on record, but they almost always see a massive winter storm in March during every La Nina winter as it wears off....often that very same storm can give the NE/MA a big snow event as well afterwards...3/15/99 and 3/7/89 are two examples of storms that dropped record snows in Kansas and Oklahoma during La Nina winters that gave snow to the NE though they were not widespread snow events and the amounts were quite variable everywhere.

[am19psu]

tony what does it mean when the mjo is in the circle of death? Is it that its not the dominating teleconnector and other teleconnectors take over?

this.

[tombo82685]

this.

yea i know that the circle of death, but when it gets in there what does that mean? Like that the mjo isnt the dominating force?

[Rainshadow]

2/11/06 and 3/15/99 are the the only examples I can think of as Chris L said....2/1989 was sort of a Miller A as was 1/2000 but both of those lows sort of formed more so off the the SC/GA coast so they were not really true Miller As if you ask me...just far south forming Miller Bs....if its gonna happen its comes late in the season generally....the southern Plains region generally is a good area to key in on for southern stream action since all of their winter weather events in southern KS and MO, all of OK, AR, and N TX are generally induced that way, hence why 87/88, 72-73 and 09/10 are in those regions top 5 snowiest winters on record, but they almost always see a massive winter storm in March during every La Nina winter as it wears off....often that very same storm can give the NE/MA a big snow event as well afterwards...3/15/99 and 3/7/89 are two examples of storms that dropped record snows in Kansas and Oklahoma during La Nina winters that gave snow to the NE though they were not widespread snow events and the amounts were quite variable everywhere.

I'd have to look at it more closely, but it does look like this nina is peaking or leveling early, which would fit the back end m.o., especially since 1955-56 as an analog (not one of mine ) is getting off to a good start.

[am19psu]

yea i know that the circle of death, but when it gets in there what does that mean? Like that the mjo isnt the dominating force?

Yeah, it just means that tropical forcing is weak or non-existent. Same thing when the GWO is in the center for AAM forcing.

[tombo82685]

Yeah, it just means that tropical forcing is weak or non-existent. Same thing when the GWO is in the center for AAM forcing.

ok thanks, i appreciate the help.

[Rainshadow]

ok thanks, i appreciate the help.

Tombo,

Lettuce is still alive, broccoli rabe, so-so. There is always next week...

[Rainshadow]

Yeah, it just means that tropical forcing is weak or non-existent. Same thing when the GWO is in the center for AAM forcing.

Yeah the GWO has been pretty much a non force for a while.

[tombo82685]

Yeah the GWO has been pretty much a non force for a while.

thats insane tony, everything has croaked her from last weeks cold

[Isotherm]

The December 13th-14th system should set-up a more conducive pattern for snow, and here's why:

1) First off, although the NAO is technically negative, this is another situation where the orientation of the block is more important than the modality of the index. East based -NAO's are generally no good w/ a strong La Nina and poor nroth pacific signal. SE ridging comes into play, and thus the short wave is allowed to cut inland/through the Lakes.

Here's the H5 appearance for early next week:

After this system bombs out, it will form a new 50-50 low in SE Canada which aids in pulling the -NAO orientation further west. So in effect, although the Dec 13th event is a lost cause for I-95, it'll play a significant role in turning the regime to a more favorable one.

Note the H5 set-up for next Thursday:

-NAO west, complete with a 50-50 low, tanking AO, and also an improving PNA. All these factors mean incoming short waves will be forced to track underneatht he blocking feature, thus a better shot at wintry precip for our neck of the woods. The GFS is already hinting at overrunning, W-E propagating, gradient type systems beginning late next week through the holiday period.

Hold onto your hats as I think the first real shot at accum snow may arrive after the 13th event.

[Isotherm]

I keep waiting and waiting for the tropical forcing to win. It's why I've been quiet all week, because I can't figure out "why" the MJO hasn't exerted more of an influence. I keep hoping you or Wes or HM will enlighten me

Roundy's stuff suggests we'll go to Phase 6 by next weekend or so, which is still a fairly warm phase for the east, but I'm not holding my breath.

In my view the solar influence has and will continue to be a major player in the Arctic/Atlantic pattern. The record low geomagnetic activity of the past two years has weakened the jet in the north atlantic and thus -NAO blocks can form with much greater ease than would typically be the case in a strong nina. The actual temp and H5 pattern over the CONUS recently has not reflected the MJO forcing at all, and this is probably because the AO/NAO are currently the major players, due in large part to the solar activity (lack thereof). Add on top of that Nina climo for the coldest period historically at the front part of the winter, and we've got pretty good reason to lock in the colder than normal pattern the rest of December. IMO as the winter wears on, particularly post mid January, the NAO/AO will exert less influence and the tropical forcing from the strong nina will eventually take over the pattern.

[Chris L]

I'd have to look at it more closely, but it does look like this nina is peaking or leveling early, which would fit the back end m.o., especially since 1955-56 as an analog (not one of mine ) is getting off to a good start.

I am sure March 1956 would be pretty ideal for the NYC area.

But generally, weak nina truly the best for the East as weak Nino also. (Save January 1996 Blizzard in a weak Nina, that was just because the setup was absolutely perfect with the Polar Jet digging to the ideal spot).

But last year tells us: our biggest snow events are Ninos.Feb 83, Feb 03, Jan 2005, Feb '78. March '93.