Pattern Change thread

[weatherwiz]

Sadly you are very misinformed, NAO rules the roost around here.

No doubt the NAO rules but I think the Pacific is a bigger player, especially in La Nina's.

[weatherMA]

Some of the local mets on Boston tv talked about it.

lol. Oh no Honey they said there will be a snowstorm in 10 days, I dont think we can travel!

[CoastalWx]

Harvey broke down the potential pattern nicely. Mentioned how the se ridge could flex, but also how the nao may influence out weather. He went for snowfall a little below normal with temps a little above normal, but mentioned he could bust in the snowier direction, and also said NNE would be very snowy potentially. He actually talked about a strong gradient in snowfall.

[MaineJayhawk]

Harvey broke down the potential pattern nicely. Mentioned how the se ridge could flex, but also how the nao may influence out weather. He went for snowfall a little below normal with temps a little above normal, but mentioned he could bust in the snowier direction, and also said NNE would be very snowy potentially. He actually talked about a strong gradient in snowfall.

I am Harvey's newest fan.

The things he outlined there ... that's been the talking points of many of the more respected mets and hobbyists here. Where there's smoke, there's fire. Keep the good vibes going, y'all.

[Tropopause_Fold]

Harvey broke down the potential pattern nicely. Mentioned how the se ridge could flex, but also how the nao may influence out weather. He went for snowfall a little below normal with temps a little above normal, but mentioned he could bust in the snowier direction, and also said NNE would be very snowy potentially. He actually talked about a strong gradient in snowfall.

one way or the other it'll be an interesting ride and another learning experience.

could be a lot of regional board warfare in the coming months. going to be tough when it's 60 in a spot like ACY or BWI and its 30F in BOS.

[ORH_wxman]

one way or the other it'll be an interesting ride and another learning experience.

could be a lot of regional board warfare in the coming months. going to be tough when it's 60 in a spot like ACY or BWI and its 30F in BOS.

It got pretty bad in December 2007. I don't know if you were lurking unregistered on eastern yet back then, but it was ugly for a few weeks there.Esp the further south crowd near DC because they hadn't had much since '02-'03 at that point.

[MaineJayhawk]

one way or the other it'll be an interesting ride and another learning experience.

could be a lot of regional board warfare in the coming months. going to be tough when it's 60 in a spot like ACY or BWI and its 30F in BOS.

Nah, the MAers will be cool with us getting buried in snow. They're a kind and understanding group.

[nzucker]

Low level cold undercutting high 5 h heights, sw flow, heavy heavy low level cold ala 94

The cold in 93-94 had little to do with the NAO and actually contradicts the point you are trying to make. 93-94 had a +NAO but was favorable because there was a big +PNA, so it was mostly the Pacific cooperating that made the winter frigid, along with the fact that the +NAO vortex was positioned pretty far south near Hudson Bay...but the main thing driving the cold pattern was the Pacific state.

Without a doubt, the Pacific is more important for arctic outbreaks and the NAO is more important for snowfall along the East Coast. A strong -NAO block like the one modeled on the 12z ECM can help counteract a poor Pacific, but it obviously depends on how unfavorable the Pacific is. In this case, the brief period of -EPO blocking happening now allows cold to drain into central Canada which sticks around for a while; even as the Pacific reverts to its natural +EPO state in the strong Niña, the cold remains for a few days and can be tapped by the powerful -NAO that the GFS and Euro are showing. So in this case, it's actually both basins cooperating for a couple of weeks to allow us to realize below normal temperatures and snow threats in the long range.

The million dollar question is what will happen as the La Niña continues to strengthen. It lost some of its cold anomalies due to the recent MJO progression, but it can do nothing but intensity now that the MJO has returned to the circle of death, the AAM is dropping precipitously, and trade winds are increasing around 150E initially and then back into the heart of the ENSO regions about 140W. Region 3.4 is currently sitting at -1.35C while the eastern regions are much colder; we'll see these cold anomalies grow in the next 2-3 weeks. This will make it exponentially harder to get a significant -EPO block to form later in the winter, and it will also team up with the low solar activity and +QBO to strengthen the PV. It may be easier to get a cold pattern in late November/early December since the PV is still relatively undeveloped, but as this features grows in importance, the pattern will naturally turn warmer in the mid-latitudes. Even when cold air does descend into the CONUS, it will be mostly in the Plains and Rockies which have colder climo in a La Niña, with high heights over the SE dominating most of the winter.

[OKpowdah]

It got pretty bad in December 2007. I don't know if you were lurking unregistered on eastern yet back then, but it was ugly for a few weeks there.Esp the further south crowd near DC because they hadn't had much since '02-'03 at that point.

Wasn't there some significant interaction between much of the Mid Atlantic gang and Kevin? lol

[Tropopause_Fold]

It got pretty bad in December 2007. I don't know if you were lurking unregistered on eastern yet back then, but it was ugly for a few weeks there.Esp the further south crowd near DC because they hadn't had much since '02-'03 at that point.

i would occasionally read the board but not enough to really follow the warfare. i can recall some pretty serious battles even in 08-09...my first real winter here.

overall...i think you have to feel OK about where we are heading for the next few weeks. how long it lasts is beyond me but the dominance and resiliency of the NAO leaves me optimistic.

[Tropopause_Fold]

The cold in 93-94 had little to do with the NAO and actually contradicts the point you are trying to make. 93-94 had a +NAO but was favorable because there was a big +PNA, so it was mostly the Pacific cooperating that made the winter frigid, along with the fact that the +NAO vortex was positioned pretty far south near Hudson Bay...but the main thing driving the cold pattern was the Pacific state.

Without a doubt, the Pacific is more important for arctic outbreaks and the NAO is more important for snowfall along the East Coast. A strong -NAO block like the one modeled on the 12z ECM can help counteract a poor Pacific, but it obviously depends on how unfavorable the Pacific is. In this case, the brief period of -EPO blocking happening now allows cold to drain into central Canada which sticks around for a while; even as the Pacific reverts to its natural +EPO state in the strong Niña, the cold remains for a few days and can be tapped by the powerful -NAO that the GFS and Euro are showing. So in this case, it's actually both basins cooperating for a couple of weeks to allow us to realize below normal temperatures and snow threats in the long range.

The million dollar question is what will happen as the La Niña continues to strengthen. It lost some of its cold anomalies due to the recent MJO progression, but it can do nothing but intensity now that the MJO has returned to the circle of death, the AAM is dropping precipitously, and trade winds are increasing around 150E initially and then back into the heart of the ENSO regions about 140W. Region 3.4 is currently sitting at -1.35C while the eastern regions are much colder; we'll see these cold anomalies grow in the next 2-3 weeks. This will make it exponentially harder to get a significant -EPO block to form later in the winter, and it will also team up with the low solar activity and +QBO to strengthen the PV. It may be easier to get a cold pattern in late November/early December since the PV is still relatively undeveloped, but as this features grows in importance, the pattern will naturally turn warmer in the mid-latitudes. Even when cold air does descend into the CONUS, it will be mostly in the Plains and Rockies which have colder climo in a La Niña, with high heights over the SE dominating most of the winter.

looks rough from about dobbs ferry points SW.

[nzucker]

looks rough from about dobbs ferry points SW.

The gradient is me

[dryslot]

It got pretty bad in December 2007. I don't know if you were lurking unregistered on eastern yet back then, but it was ugly for a few weeks there.Esp the further south crowd near DC because they hadn't had much since '02-'03 at that point.

Yeah, I remember it got pretty nasty with some from the mid atlantic trolling our threads up this way, They really got offended when we had started the so many inch club threads, But last year, They were just as bad, Not all but some as they scored the coup on snowfall......

[dryslot]

Wasn't there some significant interaction between much of the Mid Atlantic gang and Kevin? lol

Yeah, He poured some gas on the fire......

[weatherwiz]

0z GFS pretty interesting for around thanksgiving...develops a pretty potent storm on Friday but we are in the warm sector.

[Dsnowx53]

The 0z GFS seems to be favoring the split-flow idea at the end of its run, not unlike what some of the Euro Ensembles were apparently showing. Not sure if that's a coincidence.

And of course, the PV says hello. As does a west-based -NAO...which all helps to establish the split-flow in the first place.

[dryslot]

0z GFS pretty interesting for around thanksgiving...develops a pretty potent storm on Friday but we are in the warm sector.

Still a long ways out, It will move east, Euro looked to have it tracking off the coast, They locked the thread back up over at eastern......

[dryslot]

The 0z GFS seems to be favoring the split-flow idea at the end of its run, not unlike what some of the Euro Ensembles were apparently showing. Not sure if that's a coincidence.

And of course, the PV says hello. As does a west-based -NAO...which all helps to establish the split-flow in the first place.

Well, That may also help to dislodge the cold over canada and move it east.....

[ORH_wxman]

The 00z GFS looks like an El Nino pattern in the long range. All this chaotic split flow and blocking all over the place.

It would certainly be interesting if it happened, but I highly doubt it works like that. The PAC jet will definitely be a lot more furious than its trying to show there. I hope its right though because that would be an interesting pattern...but I'll stick to the high octane PAC jet idea...maybe a hint of a split flow, but not a blocked up pattern like the GFS shows.

[Dsnowx53]

The 00z GFS looks like an El Nino pattern in the long range. All this chaotic split flow and blocking all over the place.

It would certainly be interesting if it happened, but I highly doubt it works like that. The PAC jet will definitely be a lot more furious than its trying to show there. I hope its right though because that would be an interesting pattern...but I'll stick to the high octane PAC jet idea...maybe a hint of a split flow, but not a blocked up pattern like the GFS shows.

I'm starting to think that this might be a pattern where more than just interior New England cashes in. The signal for this huge blocking is overwhelming, and if there is any semblance of a split-flow, that could lead to a Miller A/B hybrid, rather than just a stream of SW-flow overrunning events.

[ORH_wxman]

I'm starting to think that this might be a pattern where more than just interior New England cashes in. The signal for this huge blocking is overwhelming, and if there is any semblance of a split-flow, that could lead to a Miller A/B hybrid, rather than just a stream of SW-flow overrunning events.

The blocking is good, but its still not very west based on the ensembles (in fact, its east on the ensemble mean)...it tries to get there near the end, but that is a long ways out. The OP run of the GFS is really blocky, but that could like be 1000% different next run.

The PAC side still favors a SE ridge trying to fight this generally east based -NAO (which may try and get more central based or even possibly west based)...we've seen this before...it happened in extremely late December 2008 and the first 10 days of Jan 2009.

I'm skeptical of a huge split flow for a coastal bomb that goes up the whole east coast as long as the PAC looks like that. We might get a miller B, but even that is not easy in this overall setup...if the GFS verifies, then yes, we could get all sorts of fun. But that is the OP GFS beyond 240h which is about as useful as throwing darts blind folded.

We'll see though, there's a lot of uncertainty with the details of the blocking on the Atlantic side after about 240 hours. The PAC side doesn't like big amplification though from what I see.

[tacoman25]

The 00z GFS looks like an El Nino pattern in the long range. All this chaotic split flow and blocking all over the place.

It would certainly be interesting if it happened, but I highly doubt it works like that. The PAC jet will definitely be a lot more furious than its trying to show there. I hope its right though because that would be an interesting pattern...but I'll stick to the high octane PAC jet idea...maybe a hint of a split flow, but not a blocked up pattern like the GFS shows.

I don't know man...big-time blocking about to commence (both sides of the continent), bigger than we've seen overall I think in any recent moderate/strong Nina. Certainly not a good sign for those in the late 90s analogs crowd.

[weatherwiz]

I think we'll see more of an overrunning type pattern than anything else, with the way the Pacific is the -NAO if it does indeed get that negative and sets up east-based will really try to fight the SE ridge so we'll have a nice battle ground and temp gradient setup over the Northeast. NNE should be able to cash in extremely well in this setup. As for places further south it's all going to depend on where exactly the gradient sets up.

[nzucker]

I don't know man...big-time blocking about to commence (both sides of the continent), bigger than we've seen overall I think in any recent moderate/strong Nina. Certainly not a good sign for those in the late 90s analogs crowd.

I never thought this winter would be nearly as warm nationally as 98-99 or 99-00, but the general signal on the 0z GFS is that the SE ridge remains intact until Day 11, with most of the cold air from the polar vortex spilling into the Pacific Northwest and Rockies. It's an impressive pattern out near you with -10C 850s approaching Las Vegas and some snow for Seattle, as well as heavy snow for the Montana, Utah, and Colorado mountain ranges, but we don't get much benefit from the initial Alaska block. I think this could be a pretty cold winter out in the PAC NW/Northern Rockies, but it just seems that the SE ridge is winning out for I-95. No hint of below average temperatures on the GFS or ECM until the uber long-range. I'm liking analogs that had a colder west like 54-55 and 88-89 more, but also throwing in some elements of 55-56 (NAO blocking and potential for big March in East Coast) as well as 73-74 (temperatures not too far above average in the Northeast, icy winter).

[ORH_wxman]

I never thought this winter would be nearly as warm nationally as 98-99 or 99-00, but the general signal on the 0z GFS is that the SE ridge remains intact until Day 11, with most of the cold air from the polar vortex spilling into the Pacific Northwest and Rockies. It's an impressive pattern out near you with -10C 850s approaching Las Vegas and some snow for Seattle, as well as heavy snow for the Montana, Utah, and Colorado mountain ranges, but we don't get much benefit from the initial Alaska block. I think this could be a pretty cold winter out in the PAC NW/Northern Rockies, but it just seems that the SE ridge is winning out for I-95. No hint of below average temperatures on the GFS or ECM until the uber long-range. I'm liking analogs that had a colder west like 54-55 and 88-89 more, but also throwing in some elements of 55-56 (NAO blocking and potential for big March in East Coast) as well as 73-74 (temperatures not too far above average in the Northeast, icy winter).

Its not looking good for Dobbs Ferry southwestward.

Just make sure you keep the good Boston analogs out of there that also screwed NYC.

[nzucker]

Its not looking good for Dobbs Ferry southwestward.

Just make sure you keep the good Boston analogs out of there that also screwed NYC.

But I am at 341' elevation so all is good. NYC mountains FTW

[ORH_wxman]

But I am at 341' elevation so all is good. NYC mountains FTW

Elevation gets trumped in most strong Ninas.

[nzucker]

Elevation gets trumped in most strong Ninas.

Yeah, I'm thinking snowfall will be slightly below normal here, maybe 25-30". I'm expecting some good arctic shots but a large variety in storm track and a mild pattern later in the winter. I do think ice storms will be a threat for NYC metro this season; we saw minor icing events in 08-09 but haven't had anything devastating recently. Interestingly enough, December 1973 had a huge ice storm for NYC in the strongest La Niña on record.

[weatherwiz]

Given how negative the NAO looks around the 28th I find it hard to believe the storm would track like that...

Although if the PNA/EPO pattern are supporting a SE ridge I could see the SE ridge doing it's best to win out, in which case maybe we would see some sort of overrunning situation.

[nzucker]

Given how negative the NAO looks around the 28th I find it hard to believe the storm would track like that...

Although if the PNA/EPO pattern are supporting a SE ridge I could see the SE ridge doing it's best to win out, in which case maybe we would see some sort of overrunning situation.

There's too much of a SE ridge to see a coastal, and it looks to me as if some energy is trying to phase into the PV over the Canadian Prairies, which is causing the system to strengthen rapidly and turn into a cutter. It needs to be weaker and have lower heights ahead of it if we want a more favorable overrunning situation.

Also, it's early in the season, which means the jet is naturally farther north and thus favors the inland/cutter solution. The storm occurs before meteorological winter even begins.