Pattern Changing: Early December threats?

[moneypitmike]

At least it's something within the realm of reason (and time!) that we can follow. Maybe for a suprise, maybe for a let down. But either way, we're moving in the right direciton. I'm actually feeling pretty good about it at the moment.

Meanwhile, happy, happy Thanksgiving!

[Damage In Tolland]

Euro looks like a nice snow to ice event for most of SNE save the coast as we thought might happen this winter

[CoastalWx]

Euro looks like a nice snow to ice event for most of SNE save the coast as we thought might happen this winter

Should be a nice inside runner by 12z.

[Damage In Tolland]

Should be a nice inside runner by 12z.

You've been beating that drum for a week lol

[CoastalWx]

You've been beating that drum for a week lol

I'm kidding around. I'm not expecting it, just saying to watch out for it. I could see a snow-ice-rain type thing, but we are so far out.

[MaineJayhawk]

Talking about 12/5 storm? I'd guess so, the next one is a monsoon.

[Damage In Tolland]

I'm kidding around. I'm not expecting it, just saying to watch out for it. I could see a snow-ice-rain type thing, but we are so far out.

A betting man would put the money on a warmer solution unfortunately

[ORH_wxman]

GFS aren't bad either. The euro op would be a big overrunning event esp for the interior up through central New England.

Tons of low level cold air on the Euro with that setup....sprawling 1040 plains high that filters the cold east. Nice to see the ensembles cool a bit from 12z too on that potential event. I think its getting safer to say that the EPO cold air dump is happening. Our only question now is how much its going to come southeast. It looks like the NAO is trying to help a little more on 00z. SE ridge is definitely still fighting it...but hey, thats they way we want it. It makes living a bit dangerously, but that is life in SWFEs.

[CoastalWx]

Tons of low level cold air on the Euro with that setup....sprawling 1040 plains high that filters the cold east. Nice to see the ensembles cool a bit from 12z too on that potential event. I think its getting safer to say that the EPO cold air dump is happening. Our only question now is how much its going to come southeast. It looks like the NAO is trying to help a little more on 00z. SE ridge is definitely still fighting it...but hey, thats they way we want it. It makes living a bit dangerously, but that is life in SWFEs.

I know the resolution obviously is not as good, but the euro ensembles sort of suggested an overrunning event, but we're riding a fine line with this one. My concern is that too much troughing occurs over the west, but hopefully that -epo does it's dirty work and dumps the cold into the nrn US.

[moneypitmike]

I know the resolution obviously is not as good, but the euro ensembles sort of suggested an overrunning event, but we're riding a fine line with this one. My concern is that too much troughing occurs over the west, but hopefully that -epo does it's dirty work and dumps the cold into the nrn US.

Fingers crossed.

[ORH_wxman]

I know the resolution obviously is not as good, but the euro ensembles sort of suggested an overrunning event, but we're riding a fine line with this one. My concern is that too much troughing occurs over the west, but hopefully that -epo does it's dirty work and dumps the cold into the nrn US.

We'll need enough help from -NAO. If we don't get it, then my forecast will be a bust....since the premise was pretty much based on a strongly -PNA/-NAO pattern. (though we've done it without the -NAO before, I just didn't think that would be the setup though)

I do like the setup though for a legit shot anyway. One thing we see time and time again when we get a big -EPO arctic intrusion is that the models almost always under estimate the cold air...esp lowest 5000 ft or so. We are still far enough out that we don't know exactly what this -EPO will look like, but as we get closer, if its still looking like it does now in the upper levels...expect to see the cooling trend commence.

A lot of threats like this tend to sneak up a bit too when they might look warm initially. I remember the 12/19/08 event had a deep western trough and it was looking like a lakes cutter until about 4 days out....then it went colder. It was also a big -EPO cold dump. It would be nice to see a large comfort zone and big margin for error, but usually with these setups, we almost always walk the line....we wouldn't call it a gradient pattern if we didnt.

[mahk_webstah]

We'll need enough help from -NAO. If we don't get it, then my forecast will be a bust....since the premise was pretty much based on a strongly -PNA/-NAO pattern. (though we've done it without the -NAO before, I just didn't think that would be the setup though)

I do like the setup though for a legit shot anyway. One thing we see time and time again when we get a big -EPO arctic intrusion is that the models almost always under estimate the cold air...esp lowest 5000 ft or so. We are still far enough out that we don't know exactly what this -EPO will look like, but as we get closer, if its still looking like it does now in the upper levels...expect to see the cooling trend commence.

A lot of threats like this tend to sneak up a bit too when they might look warm initially. I remember the 12/19/08 event had a deep western trough and it was looking like a lakes cutter until about 4 days out....then it went colder. It was also a big -EPO cold dump. It would be nice to see a large comfort zone and big margin for error, but usually with these setups, we almost always walk the line....we wouldn't call it a gradient pattern if we didnt.

That brought a foot up here, followed by 14 inches 36 hours later and steady very light snow between the two events. So in this kind of pattern the EPO is the decider so to speak? It provides just enough cold air for the -NAO to work with?

[ORH_wxman]

That brought a foot up here, followed by 14 inches 36 hours later and steady very light snow between the two events. So in this kind of pattern the EPO is the decider so to speak? It provides just enough cold air for the -NAO to work with?

EPO provides all the cold to the northern tier in this pattern...however, with a western trough digging, we are at the whim of individual short wave interaction which could produce a nice overrunning event or a lake cutter...so we just have to wait and see. What it does is simply give us a shot, but no guarantee it works.The hope is that a more strongly -NAO will help keep it toward the overrunning setup.

[Damage In Tolland]

When the west is cold chances are much better that a storm cuts to our west..very rare when the west is cold that the east is cold and snowy for extended periods. What we're seeing is La Nina pattern taking hold

[CoastalWx]

We'll need enough help from -NAO. If we don't get it, then my forecast will be a bust....since the premise was pretty much based on a strongly -PNA/-NAO pattern. (though we've done it without the -NAO before, I just didn't think that would be the setup though)

I do like the setup though for a legit shot anyway. One thing we see time and time again when we get a big -EPO arctic intrusion is that the models almost always under estimate the cold air...esp lowest 5000 ft or so. We are still far enough out that we don't know exactly what this -EPO will look like, but as we get closer, if its still looking like it does now in the upper levels...expect to see the cooling trend commence.

A lot of threats like this tend to sneak up a bit too when they might look warm initially. I remember the 12/19/08 event had a deep western trough and it was looking like a lakes cutter until about 4 days out....then it went colder. It was also a big -EPO cold dump. It would be nice to see a large comfort zone and big margin for error, but usually with these setups, we almost always walk the line....we wouldn't call it a gradient pattern if we didnt.

Yeah pretty much agree. What was your forecast, or were you saying that 12/5 would be our first threat?

12/5 has more potential then next week ever did simply from climo, but also for the reasons you stated. It is surprising some of the solutions are so warm based on the epo dump and the negative nao, but like I said a few days ago...if we keep getting this pattern later into December, it will undoubtedly trend further south with each storm. I feel pretty good about that. I don't mind the trough in the west...that's not the problem, but I just don't want it to eject out in the Plains and continue moving ne. I'd like to see a western trough that is tilted sw-ne and sort of strung out looking with a "tail" of vorticity moving away from it, instead of a concentrated vortmax. Of course the block to the north would help achieve this.

This pattern isn't bad, but I think people need to give it a chance, because having this pattern even three weeks from now I think would be a colder solution for most. It's just that everyone is under the impression that we only have December to snow, so everybody is scared out of their minds if we don't start to snow right away.

[weatherwiz]

Looks like the main s/w there on the 0z GFS tries to no negatively tilted way too early and it also phases with the piece that is broken off from the PV (or whatever that is) and once it phases the low rapidly deepens and strengthens and since it went negatively tilted way too early it cuts off to our west.

[ORH_wxman]

Yeah pretty much agree. What was your forecast, or were you saying that 12/5 would be our first threat?

12/5 has more potential then next week ever did simply from climo, but also for the reasons you stated. It is surprising some of the solutions are so warm based on the epo dump and the negative nao, but like I said a few days ago...if we keep getting this pattern later into December, it will undoubtedly trend further south with each storm. I feel pretty good about that. I don't mind the trough in the west...that's not the problem, but I just don't want it to eject out in the Plains and continue moving ne. I'd like to see a western trough that is tilted sw-ne and sort of strung out looking with a "tail" of vorticity moving away from it, instead of a concentrated vortmax. Of course the block to the north would help achieve this.

This pattern isn't bad, but I think people need to give it a chance, because having this pattern even three weeks from now I think would be a colder solution for most. It's just that everyone is under the impression that we only have December to snow, so everybody is scared out of their minds if we don't start to snow right away.

No I didn't have a specific date, only that the period beyond Thanksgiving to about Dec 10th would be the period to watch with a -NAO/-PNA setup...but if the -NAO sort of craps the bed, then I would say I was wrong. I certainly wouldn't try to actually nail a snowfall date that far out (unless its for fun like a contest)...that's clown zhit, lol.

I think my timing with everything though is going to end up about 4-5 days too quickly. It looks more and more like we remain in a decent pattern beyond Dec 10th, after not kicking in until Dec 3rd or so...instead of 11/28-29ish. But then again, I never was a long range expert, so I'd expect to get it wrong a lot.

I do have confidence that if this -EPO comes to fruition, we'll see a colder look as we get closer. That's been my experience with these types of patterns.

[CoastalWx]

BTW for those who are wondering, this is what I mean by sw-ne tilted trough with a more strung out look to vorticity.

[CoastalWx]

No I didn't have a specific date, only that the period beyond Thanksgiving to about Dec 10th would be the period to watch with a -NAO/-PNA setup...but if the -NAO sort of craps the bed, then I would say I was wrong. I certainly wouldn't try to actually nail a snowfall date that far out (unless its for fun like a contest)...that's clown zhit, lol.

I think my timing with everything though is going to end up about 4-5 days too quickly. It looks more and more like we remain in a decent pattern beyond Dec 10th, after not kicking in until Dec 3rd or so...instead of 11/28-29ish. But then again, I never was a long range expert, so I'd expect to get it wrong a lot.

I do have confidence that if this -EPO comes to fruition, we'll see a colder look as we get closer. That's been my experience with these types of patterns.

I think that remains quite a feature. Maybe I'm wrong too, but go back and look at forecasts 5 days ago, and compare it to now. Looks solid. I think that's a decent call up to 12/10, especially considering when you made it.

[ORH_wxman]

I think that remains quite a feature. Maybe I'm wrong too, but go back and look at forecasts 5 days ago, and compare it to now. Looks solid. I think that's a decent call up to 12/10, especially considering when you made it.

Well the initial setup crapped the bed a bit which is probably why we see the delay in the pattern...originally it was supposed to rip west and trap a bit of a vortex underneath it in SE Canada by early next week...but instead it turns more east based and more into a N ATL ridge before trying to build back into a more ideal block later on. The uglier setup next week undoubtedly is what is promoting the 12/1 storm to be a huge lakes cutter.

But hopefully that's the end of it. It is encouraging to see the Euro ensembles going more with a -NAO look in the extended period...which actually matches the OP run look at 240h.

[weatherwiz]

How much does a -EPO actually help us during Nina's though? Especially moderate to strong ones? -EPO's seem quite common during La Nina episodes as there haven't been many long-term (or monthly) EPO data that are positive during Nina's. Even the warmest Nina's (1998-1999, 1999-2000) had a pretty -EPO. Do you also need to have a -NAO in place?

[CoastalWx]

Well the initial setup crapped the bed a bit which is probably why we see the delay in the pattern...originally it was supposed to rip west and trap a bit of a vortex underneath it in SE Canada by early next week...but instead it turns more east based and more into a N ATL ridge before trying to build back into a more ideal block later on. The uglier setup next week undoubtedly is what is promoting the 12/1 storm to be a huge lakes cutter.

But hopefully that's the end of it. It is encouraging to see the Euro ensembles going more with a -NAO look in the extended period...which actually matches the OP run look at 240h.

Oh I see what you're saying. Yeah it did trend away from the west based look and it also got a little nastier looking out west. It trended west a little towards the end of the 00z run, but maybe we'll have to watch if that is a model bias. Maybe the block will trend east again. In any case, that is certainly a nice block to see in the middle of winter.

[ORH_wxman]

How much does a -EPO actually help us during Nina's though? Especially moderate to strong ones? -EPO's seem quite common during La Nina episodes as there haven't been many long-term (or monthly) EPO data that are positive during Nina's. Even the warmest Nina's (1998-1999, 1999-2000) had a pretty -EPO. Do you also need to have a -NAO in place?

Absolutely false.

[Ginx snewx]

GFS aren't bad either. The euro op would be a big overrunning event esp for the interior up through central New England.

So Zucker is right, especially since I posted the Ens look good, cold enough for snow ETC? Really?

[weatherwiz]

Absolutely false.

I was just looking at the numerical value of the EPO.

1999:

January -1.03

February: -0.70

2000:

January: -1.06

February: -0.18

[CoastalWx]

So Zucker is right, especially since I posted the Ens look good, cold enough for snow ETC? Really?

What's ETC??

[Ginx snewx]

What's ETC??

LOL etc etc etc things look good to me, has that 94 low level cold, overrunning look to me. I was speaking from Dec 3 on. He flat out said there was zero chances except for the mountains. Again I was speaking using generalizations of the look to Ens.

[ORH_wxman]

I was just looking at the numerical value of the EPO.

1999:

January -1.03

February: -0.70

2000:

January: -1.06

February: -0.18

Where are you getting those numbers from? If its the esrl data, I believe they have them all reversed because they are using old EP/NP values to substitute for the EPO....EPO has the opposite sign of the EP/NP. Those maps I showed have an extreme positive EPO, no ifs, ands, or buts....that's about as bad as it gets for cold in the CONUS.

We talked about it all autumn....we didn't want a big vortex over AK. Esp Bering straight.

[CoastalWx]

LOL etc etc etc things look good to me, has that 94 low level cold, overrunning look to me. I was speaking from Dec 3 on. He flat out said there was zero chances except for the mountains. Again I was speaking using generalizations of the look to Ens.

Yeah I mean, it does have that overrunning look to it with a big high to the north, but it very well could go overhead or just to the west. we just don't know. It definitely has a better chance as compared to the storm coming next week, so give it a shot. I could see the warmfront getting to a position from TOL-WST, while Moosup and ORH...points northeast have frozen.

[CoastalWx]

Where are you getting those numbers from? If its the esrl data, I believe they have them all reversed because they are using old EP/NP values to substitute for the EPO....EPO has the opposite sign of the EP/NP. Those maps I showed have an extreme positive EPO, no ifs, ands, or buts....that's about as bad as it gets for cold in the CONUS.

We talked about it all autumn....we didn't want a big vortex over AK. Esp Bering straight.

That's really confusing. Why did they do this?? To better align with the PNA?? I think the correlations also use this new method too. They should just use one index and that's it.