Pattern Change thread

[tacoman25]

Looks like the Euro really floods the US with Pacific air...all the cold stays up in Canada.

That's not really the issue...it's more that more energy is held back longer further west, which helps keep the SE ridge on roids longer and prevents the PV from slipping to the east like the GFS showed. I think a compromise between the GFS and the Euro is probably the best bet at this point.

[nzucker]

The T-day storm is a long shot at best. The favorable New England pattern sets in after it. The PV lobe will be forced underneath the NAO block into SE Canada....that's when we'll see our chances.

As I said earlier in the thread last page...if we get the T-day event, a total bonus and gravy, but we certainly aren't counting on it. EC is pretty much an outlier though with its D10 pattern, the ensembles will undoubtedly not support it. I think its too bottled up considering that even the OP EC has a huge greenland block.

It looks like the 0z ECM keeps the PV bottled up in Canada due to zonal flow ahead of the strong negative height anomaly in the GoA; the old polar low is breaking down and a new PV is forming over Siberia which definitely isn't as favorable.

When do the ECM ENS come out?

[weatherwiz]

That's not really the issue...it's more that more energy is held back longer further west, which helps keep the SE ridge on roids longer and prevents the PV from slipping to the east like the GFS showed. I think a compromise between the GFS and the Euro is probably the best bet at this point.

At 240 HR still looks like there would be some sort of temp gradient over the Northeast but yeah it does have some energy back across the OV region with some heights still trying to build into the Northeast but looks like the -NAO tries to fight it

[ORH_wxman]

It looks like the 0z ECM keeps the PV bottled up in Canada due to zonal flow ahead of the strong negative height anomaly in the GoA; the old polar low is breaking down and a new PV is forming over Siberia which definitely isn't as favorable.

When do the ECM ENS come out?

They come out in about half an hour.

[nzucker]

At 240 HR still looks like there would be some sort of temp gradient over the Northeast but yeah it does have some energy back across the OV region with some heights still trying to build into the Northeast but looks like the -NAO tries to fight it

This run isn't impressive at all. The storm in the OH Valley would be much too warm for most of the Northeast, and the Pacific pattern is clearly creating a zonal flow across the CONUS with the main PV reforming in Siberia. You can see that the last bit of remaining cold in North America is totally bottled up near Hudson Bay north of the zonal jet, and it's basically fading as the unfavorable, Niña-like Pacific forces the PV and all its associated cold air back towards Eurasia....we hardly have any -20C 850s left in Canada whereas right now there is -30C there and it's almost two weeks later at the end of the ECM.

[ORH_wxman]

This run isn't impressive at all. The storm in the OH Valley would be much too warm for most of the Northeast, and the Pacific pattern is clearly creating a zonal flow across the CONUS with the main PV reforming in Siberia. You can see that the last bit of remaining cold in North America is totally bottled up near Hudson Bay north of the zonal jet, and it's basically fading as the unfavorable, Niña-like Pacific forces the PV and all its associated cold air back towards Eurasia....we hardly have any -20C 850s left in Canada whereas right now there is -30C there and it's almost two weeks later at the end of the ECM.

The PV lobe even on the 00z OP Euro has to come east...it cant go north with the NAO greenland block. It would become favorable after that period.

[nzucker]

The PV lobe even on the 00z OP Euro has to come east...it cant go north with the NAO greenland block. It would become favorable after that period.

I don't see any mechanism really pushing the cold south such as a +PNA or -EPO...the storm over the OH Valley is going to be a cutter and by then most of the cold airmass will have moderated. Sure, there'll be a few chilly days in New England after the cutter passes, but the gradient will remain too far north for meaningful snows along most of the East Coast. I don't see any signs of cross-polar flow and the NAO block seems to be too weak to battle the dominant SE ridge. Do you really think this is such a great pattern?

In my opinion, the 0z ECM is a step in the wrong direction from what we saw at 12z on the ECM and on the last two runs of the GFS. Do you agree Will?

[ORH_wxman]

I don't see any mechanism really pushing the cold south such as a +PNA or -EPO...the storm over the OH Valley is going to be a cutter and by then most of the cold airmass will have moderated. Sure, there'll be a few chilly days in New England after the cutter passes, but the gradient will remain too far north for meaningful snows along most of the East Coast. I don't see any signs of cross-polar flow and the NAO block seems to be too weak to battle the dominant SE ridge. Do you really think this is such a great pattern?

In my opinion, the 0z ECM is a step in the wrong direction from what we saw at 12z on the ECM and on the last two runs of the GFS. Do you agree Will?

The cold wont come south without a big +PNA...that was never the idea. NAO will push it east though and should hit New England and the Great Lakes.

I know you are trying to not make it snow here....but the weather will do what it wants. We'll see who is right and who is wrong by Dec 10th. My bet is we end up with a below avg regime after T-day and there will be threats. No guarantee the snow threats work out...but they will be there and the temps should avg below normal.

[ski MRG]

The cold wont come south without a big +PNA...that was never the idea. NAO will push it east though and should hit New England and the Great Lakes.

I know you are trying to not make it snow here....but the weather will do what it wants. We'll see who is right and who is wrong by Dec 10th. My bet is we end up with a below avg regime after T-day and there will be threats. No guarantee the snow threats work out...but they will be there and the temps should avg below normal.

The Zucker Model has an obvious warm bias.

[nzucker]

The cold wont come south without a big +PNA...that was never the idea. NAO will push it east though and should hit New England and the Great Lakes.

I know you are trying to not make it snow here....but the weather will do what it wants. We'll see who is right and who is wrong by Dec 10th. My bet is we end up with a below avg regime after T-day and there will be threats. No guarantee the snow threats work out...but they will be there and the temps should avg below normal.

I don't care if it snows there. I think you are getting the wrong impression about my winter forecast and my feelings regarding December. I predicted a cold/snowy pattern for December, so it would be a bust for my personal forecast if it doesn't happen. I also don't think SNE will get that much snow later in the season, so even if Boston gets 20-25" in December, which would be huge for Logan, I doubt I'd lose my general wagering with Jerry about the winter snowfall total. I was actually getting pretty excited after the 12z ECM and 0z GFS I just think the ECM moved in the wrong direction from 12z to 0z...take a look at it objectively and tell me which is better:

Old run:

New run:

The old run had a much better pattern over the Pacific with the +PNA developing and forcing a much stronger/cold PV farther south; heights were clearly going down over the East Coast as the west-based NAO was strong on 12z and pushed the Bermuda high out of the way. The 0z keeps a more zonal flow over the CONUS, the PV is dissipating and too far north, and the SE ridge is still a player. These are just objective observations and have nothing to do with my personal forecasts or bias.

[ORH_wxman]

The Zucker Model has an obvious warm bias.

He's just protecting his BOS 35-39" snowfall forecast...if they get good snow in December, he knows he is in deep doo-doo.

[NJwinter23]

The T-day storm is a long shot at best. The favorable New England pattern sets in after it. The PV lobe will be forced underneath the NAO block into SE Canada....that's when we'll see our chances.

As I said earlier in the thread last page...if we get the T-day event, a total bonus and gravy, but we certainly aren't counting on it. EC is pretty much an outlier though with its D10 pattern, the ensembles will undoubtedly not support it. I think its too bottled up considering that even the OP EC has a huge greenland block.

I am a little shocked seeing the lack of cold air in the CONUS on this solution of the op Euro by day 10..Differences in what's going on over Alaska and Western Canada in that time frame seems to be a big reason for the different look from previous runs. We are talking about day 10 though so I don't think we should be surprised at some flip-flopping in specifics run to run. What's important is that every run continues to at least show this massive -NAO block. I'd also expect the ensemble mean to be much colder in the CONUS because of the block. Even on the op run at day 10, the intense PV in Central Canada appears to be heading east and about to slip under the Greenland block.

[ski MRG]

He's just protecting his BOS 35-39" snowfall forecast...if they get good snow in December, he knows he is in deep doo-doo.

Extreme model hugging.

[ORH_wxman]

I don't care if it snows there. I think you are getting the wrong impression about my winter forecast and my feelings regarding December. I predicted a cold/snowy pattern for December, so it would be a bust for my personal forecast if it doesn't happen. I also don't think SNE will get that much snow later in the season, so even if Boston gets 20-25" in December, which would be huge for Logan, I doubt I'd lose my general wagering with Jerry about the winter snowfall total. I was actually getting pretty excited after the 12z ECM and 0z GFS I just think the ECM moved in the wrong direction from 12z to 0z...take a look at it objectively and tell me which is better:

Old run:

New run:

The old run had a much better pattern over the Pacific with the +PNA developing and forcing a much stronger/cold PV farther south; heights were clearly going down over the East Coast as the west-based NAO was strong on 12z and pushed the Bermuda high out of the way. The 0z keeps a more zonal flow over the CONUS, the PV is dissipating and too far north, and the SE ridge is still a player. These are just objective observations and have nothing to do with my personal forecasts or bias.

Obviously the old run was better, but you are sticking a deterministic model run in front of me at 240 hours and using it to prove a point when in reality theres a good chance it will show us with -15C 850 temps tomorrow at 12z. That's pretty poor reasoning.

I want to hear actual physical reasons why the pattern wont be favorable for a snow event in the 10 days past Thanksgiving here.

[ORH_wxman]

Also if you are actually predicting nearly 2 feet of snow at Logan airport in December and still saying they will finish below average, that is a first in recorded history....tough to do obviously if its a first.

[ORH_wxman]

I am a little shocked seeing the lack of cold air in the CONUS on this solution of the op Euro by day 10..Differences in what's going on over Alaska and Western Canada in that time frame seems to be a big reason for the different look from previous runs. We are talking about day 10 though so I don't think we should be surprised at some flip-flopping in specifics run to run. What's important is that every run continues to at least show this massive -NAO block. I'd also expect the ensemble mean to be much colder in the CONUS because of the block. Even on the op run at day 10, the intense PV in Central Canada appears to be heading east and about to slip under the Greenland block.

As I told NZucker, I wouldn't put much stock into a deterministic run at 240 hours. Even if its right, that PV lobe has to come east with the NAO block. But I also don't think its right.

[nzucker]

He's just protecting his BOS 35-39" snowfall forecast...if they get good snow in December, he knows he is in deep doo-doo.

I actually think Boston will get some decent snow in December; I'm just counting on the rest of the winter to be crappy except for maybe one good storm in March. I just don't see Logan Airport getting more than 15" or so even in a favorable pattern during December, since it sticks out too much towards the warm Atlantic SSTs which is a major disadvantage early season especially if we get a gradient pattern with SW flow events that feature easterly surface winds and marginal 850s due to the Pacific not allowing Canada to build arctic air. I could easily see BOS getting 45" this winter, just not the 70" with two KU events that some weenies on this board are predicting. I'm not saying the winter will be horrible for them, just around normal snowfall with slightly above average temperatures. I think that is reasonable given the strong La Niña and poor SST configuration in the GoA. Even Jerry's three main analogs averaged out to around 42" of snow for Logan, which doesn't justify a 73" forecast in my opinion. You can't just magically add two KUs to your forecast because of an SST pattern that doesn't even exist anymore. I think my winter forecast is pretty solid, and nothing about this "great pattern" coming up is going to sway me. It is late November/early December when average highs are still in the mid-upper 40s for the coastal plain, and the Pacific pretty much sucks. A storm just cut to the west of us, another one is going to do so next Tuesday/Wednesday, and then the ECM shows a third cutter with the cold air dissipating. What is so wonderful about that?

Obviously the old run was better, but you are sticking a deterministic model run in front of me at 240 hours and using it to prove a point when in reality theres a good chance it will show us with -15C 850 temps tomorrow at 12z. That's pretty poor reasoning.

I want to hear actual physical reasons why the pattern wont be favorable for a snow event in the 10 days past Thanksgiving here.

I'm not saying the 10 day ECM forecast is entirely right, but I think it makes more sense than the weenie panels of the 0z GFS that show some insane block with -15C 850s for NYC and heavy snow in RIC during the first days of December. When the Pacific is cooling, we usually get an unfavorable pattern for most of the East Coast except perhaps NNE and some elevated areas of SNE like your house. The burst of trade winds and lack of activity from the MJO argues that a -PNA/+EPO will be in place with a strong SE ridge. SSTs in the North Pacific support this pattern and will serve to enhance it. Most model guidance shows that the cold air is fading from Canada and returning to the Siberian side, which makes sense considering what the Pacific is doing. I agree that the Atlantic is somewhat favorable which should allow for a gradient pattern, but that may not be enough for snow in late November or early December, especially for places like Boston on the coast or even Worcester. Obviously elevated parts of NNE like the Green Mtns are a different story as they are climatologically favored to see snow at this time of year.

[NJwinter23]

I actually think Boston will get some decent snow in December; I'm just counting on the rest of the winter to be crappy except for maybe one good storm in March. I just don't see Logan Airport getting more than 15" or so even in a favorable pattern during December, since it sticks out too much towards the warm Atlantic SSTs which is a major disadvantage early season especially if we get a gradient pattern with SW flow events that feature easterly surface winds and marginal 850s due to the Pacific not allowing Canada to build arctic air. I could easily see BOS getting 45" this winter, just not the 70" with two KU events that some weenies on this board are predicting. I'm not saying the winter will be horrible for them, just around normal snowfall with slightly above average temperatures. I think that is reasonable given the strong La Niña and poor SST configuration in the GoA. Even Jerry's three main analogs averaged out to around 42" of snow for Logan, which doesn't justify a 73" forecast in my opinion. You can't just magically add two KUs to your forecast because of an SST pattern that doesn't even exist anymore. I think my winter forecast is pretty solid, and nothing about this "great pattern" coming up is going to sway me. It is late November/early December when average highs are still in the mid-upper 40s for the coastal plain, and the Pacific pretty much sucks. A storm just cut to the west of us, another one is going to do so next Tuesday/Wednesday, and then the ECM shows a third cutter with the cold air dissipating. What is so wonderful about that?

I'm not saying the 10 day ECM forecast is entirely right, but I think it makes more sense than the weenie panels of the 0z GFS that show some insane block with -15C 850s for NYC and heavy snow in RIC during the first days of December. When the Pacific is cooling, we usually get an unfavorable pattern for most of the East Coast except perhaps NNE and some elevated areas of SNE like your house. The burst of trade winds and lack of activity from the MJO argues that a -PNA/+EPO will be in place with a strong SE ridge. SSTs in the North Pacific support this pattern and will serve to enhance it. Most model guidance shows that the cold air is fading from Canada and returning to the Siberian side, which makes sense considering what the Pacific is doing. I agree that the Atlantic is somewhat favorable which should allow for a gradient pattern, but that may not be enough for snow in late November or early December, especially for places like Boston on the coast or even Worcester. Obviously elevated parts of NNE like the Green Mtns are a different story as they are climatologically favored to see snow at this time of year.

I'm not going to get in the middle of this, but concerning the bolded comment..The "insane block" you speak of on the 00z gfs is every bit as strong/insane (whatever you want to call it) on the op 00z euro. So when you say the EC day 10 makes more sense then the gfs day 10 for that reason , well that doesnt really make any sense to me.

[nzucker]

Do you have the ENS Will?

[ORH_wxman]

I agree that the Atlantic is somewhat favorable which should allow for a gradient pattern, but that may not be enough for snow in late November or early December, especially for places like Boston on the coast or even Worcester. Obviously elevated parts of NNE like the Green Mtns are a different story as they are climatologically favored to see snow at this time of year.

I'll remember this the next time we get killed by SSTs in an early event at 900 feet and 40 miles inland.

I might have to wait a while though.

[nzucker]

I'm not going to get in the middle of this, but concerning the bolded comment..The "insane block" you speak of on the 00z gfs is every bit as strong/insane (whatever you want to call it) on the op 00z euro. Just other details are different. So when you say the EC day 10 makes more sense then the gfs day 10 for that reason , well that doesnt really make any sense to me.

What I am saying is that the ECM Pacific pattern makes more sense considering what's currently going on with ENSO/AAM/MJO. The GFS also builds a hefty block into the Pacific side and allows for cold air to drain down into the CONUS from Canada when combined with the -NAO, whereas this run of the ECM shows a more normal Niña-like Pacific which seems logical given what's happening. The models have obviously been waffling a lot so I'm not prepared to buy into every single run, but I'd like to see more consistency in the +PNA/-EPO depiction before I embrace the idea of a pattern change with cold temperatures and snow.

EDIT: And no, Will, you won't get killed by SSTs in your location...it's just the warmer 850s that'll make it harder to snow.

[nzucker]

Looks pretty decent...GoA low but somewhat of a +PNA and some cold air from the PV over Canada entering the Northeast.

Getting so far out though. Does it still show the cutter at Day 10 like the OP, Will?

[NJwinter23]

What I am saying is that the ECM Pacific pattern makes more sense considering what's currently going on with ENSO/AAM/MJO. The GFS also builds a hefty block into the Pacific side and allows for cold air to drain down into the CONUS from Canada when combined with the -NAO, whereas this run of the ECM shows a more normal Niña-like Pacific which seems logical given what's happening. The models have obviously been waffling a lot so I'm not prepared to buy into every single run, but I'd like to see more consistency in the +PNA/-EPO depiction before I embrace the idea of a pattern change with cold temperatures and snow.

EDIT: And no, Will, you won't get killed by SSTs in your location...it's just the warmer 850s that'll make it harder to snow.

I assumed when you said block you were talking about the NAO. Pacific block on the gfs? Are you referring to beyond day 10 now?

[ORH_wxman]

Looks pretty decent...GoA low but somewhat of a +PNA and some cold air from the PV over Canada entering the Northeast.

Getting so far out though. Does it still show the cutter at Day 10 like the OP?

No, it forces it south....doesn't mean the OP is wrong though. But that system is question mark anyway. Its the pattern after that which is the key. If we get snow/ice out of that first system its all gravy.

[Dsnowx53]

I didn't know the ensemble means came out this early...thanks for indulging us

[nzucker]

No, it forces it south....doesn't mean the OP is wrong though. But that system is question mark anyway. Its the pattern after that which is the key. If we get snow/ice out of that first system its all gravy.

Thanks for all the help and updates Will...bedtime for me now. We'll see what the models show tomorrow.

[Ice Warrior commander]

Will, Thanks for the peek at the ENS

[ORH_wxman]

The main point the EC ensembles have been hammering is the PV lobe gets forced into SE Canada. Thats a cold pattern for the east, and especially NE....it could mean some clipper/redevelopers too. That type of pattern supports a snow threat here in the 10 days beyond T-day.

[ORH_wxman]

That is also a ridiculous -NAO signal for that far out on a smoothed ensemble mean...you can clearly see how much it wants to raise heights over Greenland.

[dendrite]

Will, Thanks for the peek at the ENS

Allan's are out.

http://raleighwx.americanwx.com/models/ecmwfens.html