Pattern Changing: Early December threats?

[Tropopause_Fold]

Not necessarily...PDII and January 1996 were huge snowstorms with brutally cold airmasses.

I think people are underestimating how cold it needs to be to snow in late November/early December. This is not the time of year to be counting on marginal airmasses.

this is waaayyyyy too much of a generalization. so many things play into it.

[ORH_wxman]

ECMWF ensembles have a very interesting signal for the Dec 1st time frame....same period as that amped up 240h OP Euro solution.

[CoastalWx]

The euro ensembles show a potential Miller B developing overhead as well at D10. It's definitely not in a good position verbatim, but the fact that the mean thicknesses are relatively cold maybe implies some members further south. That event really could go either way. For the sake of the board sanity..hopefully it's snow..lol.

[CoastalWx]

Will, what do you make of the mean showing an elongated surface trough extending west from the low? It looks like it's hinting a a very slow moving upper level low, with some members probably going for a slow departure of the low.

[CT Rain]

Will, what do you make of the mean showing an elongated surface trough extending west from the low? It looks like it's hinting a a very slow moving upper level low, with some members probably going for a slow departure of the low.

Euro ensembles look sweet for Tue/Wed next week somewhere in NE.

[CoastalWx]

Euro ensembles look sweet for Tue/Wed next week somewhere in NE.

Yeah no kidding.

[CT Rain]

Yeah no kidding.

I'd like the closed low a bit further south to keep development a bit further south but this looks like a "cold" system with plenty of confluence up north.

[ORH_wxman]

Will, what do you make of the mean showing an elongated surface trough extending west from the low? It looks like it's hinting a a very slow moving upper level low, with some members probably going for a slow departure of the low.

Yeah I bet some ensemble members have a stalled system just spinning off shore.

Also looks like an Archambault signal for Dec 5-6? Obviously thats so far out...but it finally breaks down the NAO block and it definitely has some sort of system in the east. But given the magnitude of the NAO block, they would probably be rushing its demise.

[CoastalWx]

Yeah I bet some ensemble members have a stalled system just spinning off shore.

Also looks like an Archambault signal for Dec 5-6? Obviously thats so far out...but it finally breaks down the NAO block and it definitely has some sort of system in the east. But given the magnitude of the NAO block, they would probably be rushing its demise.

Yeah if you go back even 4 days ago, the models break down the nao block quicker, than what's being modeled right now. I see that signal around 12/5 as well. My only concern is that low pressure seems like it wants to hug the coast, but you can't really worry about that right now.

[CT Rain]

Yeah if you go back even 4 days ago, the models break down the nao block quicker, than what's being modeled right now. I see that signal around 12/5 as well. My only concern is that low pressure seems like it wants to hug the coast, but you can't really worry about that right now.

You've gotta think that with some strong confluence to the north anything that develops in future runs could "trend" south.

[nzucker]

Yeah if you go back even 4 days ago, the models break down the nao block quicker, than what's being modeled right now. I see that signal around 12/5 as well. My only concern is that low pressure seems like it wants to hug the coast, but you can't really worry about that right now.

Yeah that's a pretty intense signal for a storm that far out, and there's been a lot of hints about the early December pattern with the -NAO retrograding...maybe we see a big Archembault event before the NAO blocking blows up and the milder period that HM has discussed begins? I'm still a little bit worried about the amount of ridging the system gains due to the Pacific, but it'll be interesting...very robust solution especially for NNE on the 12z ECM. Interesting how the models have changed places recently.

[ORH_wxman]

Yeah if you go back even 4 days ago, the models break down the nao block quicker, than what's being modeled right now. I see that signal around 12/5 as well. My only concern is that low pressure seems like it wants to hug the coast, but you can't really worry about that right now.

I won't be surprised if the block doesn't really break down until after the 10th. We always know about the models rushing things...and yeah, we are in the process of seeing the models push it back further and further.

It will be a ton of model headaches I'm sure though before we even think about that. We'll have to figure what the heck is going on with the retrogression of the NAO block and associated 50/50 low that tries to actually phase into a midwest trough....at least we saw that on the OP run and the ensembles hinted at it.

[CoastalWx]

You've gotta think that with some strong confluence to the north anything that develops in future runs could "trend" south.

Yeah, just something I noticed. A little concerned with troughing a little too far west for MY liking, but it will benefit someone in New England. Like you said, we could see adjustments south.

[CT Rain]

I won't be surprised if the block doesn't really break down until after the 10th. We always know about the models rushing things...and yeah, we are in the process of seeing the models push it back further and further.

It will be a ton of model headaches I'm sure though before we even think about that. We'll have to figure what the heck is going on with the retrogression of the NAO block and associated 50/50 low that tries to actually phase into a midwest trough....at least we saw that on the OP run and the ensembles hinted at it.

I think the models are probably overdoing the retrogression and subsequent phasing so far west. It's a pretty unusual setup to see a 50/50 low retrograde 1500 miles and then phase into a deep closed low near Chicago lol. My gut tells me the Tuesday-Saturday period in the first week of December could have 1 or 2 fun storms for us. I'm glad that we're also seeing this pattern a week later after Thanksgiving... climo for HFD/BOS is much better by Dec 1 than 11/20.

[CoastalWx]

I won't be surprised if the block doesn't really break down until after the 10th. We always know about the models rushing things...and yeah, we are in the process of seeing the models push it back further and further.

It will be a ton of model headaches I'm sure though before we even think about that. We'll have to figure what the heck is going on with the retrogression of the NAO block and associated 50/50 low that tries to actually phase into a midwest trough....at least we saw that on the OP run and the ensembles hinted at it.

I like it overall. We get an active pattern potentially, and I think somebody..if not many will be off and running by the 10th.

[nzucker]

I won't be surprised if the block doesn't really break down until after the 10th. We always know about the models rushing things...and yeah, we are in the process of seeing the models push it back further and further.

It will be a ton of model headaches I'm sure though before we even think about that. We'll have to figure what the heck is going on with the retrogression of the NAO block and associated 50/50 low that tries to actually phase into a midwest trough....at least we saw that on the OP run and the ensembles hinted at it.

The ECM also shows a huge ridge developing over Kamchatka/Siberia and starting to push cold air back towards the Canadian side at Day 10. A ways out but interesting to see as the above average heights in that region spawned the huge cold outbreak in the West this week. Maybe the NAO block will allow that cold to flow into the East eventually. Just a strange pattern with a record-breaking -NAO block combined with a potentially record strong La Niña.

[CT Rain]

The correlation between sfc T and NAO is much stronger in December than it is in November in SNE. Interesting to watch the impacts of the block change as wavelengths increase.

[Ginx snewx]

The similarity to last Dec, first system cuts develops secondary, ten days later boom boom pow.

[ski MRG]

Not necessarily...PDII and January 1996 were huge snowstorms with brutally cold airmasses.

I think people are underestimating how cold it needs to be to snow in late November/early December. This is not the time of year to be counting on marginal airmasses if you live in the southland, like Dobbs Ferry,NY.

Yeah tough for you guys to get snow in January let alone November.

[ski MRG]

I like it overall. We get an active pattern potentially, and I think somebody..if not many will be off and running by the 10th.

Hi.

[Ginx snewx]

http://www.ecoearth.info/shared/reader/welcome.aspx?linkid=72088

Why the predicted tanking of the AO is a fantastic sign for us.

n the July 6 edition of the journal "Science," researchers report finding a strong correlation between the Arctic Oscillation's negative phase and near-record cold days and snow storms over a much broader region of the hemisphere than was previously thought.

In its negative phase, the Arctic Oscillation's ring of air spins more slowly and is more easily disturbed, allowing cold Arctic air to spill out of the far north regions and into mid-latitudes. In the positive phase, the ring of air spins faster and acts much as a dam that impedes frigid air moving south.

"The Arctic Oscillation flips back and forth a lot between positive and negative phases within a winter," Thompson said. "These changes affect weather throughout much of the hemisphere."

Arctic Oscillation effects on weather patterns appear to be as far-reaching as those triggered by El Niño in the South Pacific.

Thompson and Wallace found that days on which the Arctic Oscillation is in its negative phase are on average several degrees colder than normal over most of the United States, Northern Europe, Russia, China and Japan.

Cities with normally mild winters, such as Seattle, Dallas, Paris and Tokyo, experience most of their subfreezing temperatures and snow and ice storms on negative-phase days.

Negative-phase days bring to New England a greater likelihood of strong coastal storms....

[nzucker]

Yeah tough for you guys to get snow in January let alone November.

Not really...I had 70" at my house last year which is more than most of SNE. I also live at 350' in a heavily wooded area.

[CT Rain]

No one posted the 18z GFS weather porn?

Looks like Wednesday could be our first legit winter threat guys

[MaineJayhawk]

No one posted the 18z GFS weather porn?

Looks like Wednesday could be our first legit winter threat guys

I brought it up in the SNE discussion/banter thread, but your niece Donna Downer at the Pit wasn't impressed.

[ORH_wxman]

No one posted the 18z GFS weather porn?

Looks like Wednesday could be our first legit winter threat guys

Well we've definitely seen some interest in the Dec 1-2 time frame for a few model runs now. Block forces some interesting shortwaves underneath and the stall potential is there too, but that's probably just getting too greedy at this time frame. We need to get the storm in place first.

[CT Rain]

Well we've definitely seen some interest in the Dec 1-2 time frame for a few model runs now. Block forces some interesting shortwaves underneath and the stall potential is there too, but that's probably just getting too greedy at this time frame. We need to get the storm in place first.

Nice to see what looked like potential in the enesmbles turn into some actually storminess on the op runs. Good sign.

[ORH_wxman]

Nice to see what looked like potential in the enesmbles turn into some actually storminess on the op runs. Good sign.

Yeah, I think the OP runs are starting to see the ferocity of that block...esp the Euro which had been sort of ignoring it on its OP run for a few in a row, but now its gone a cooler/stormier look in the long range.

[CT Rain]

Yeah, I think the OP runs are starting to see the ferocity of that block...esp the Euro which had been sort of ignoring it on its OP run for a few in a row, but now its gone a cooler/stormier look in the long range.

It's much better to see the potential coming from the ensemble forecasts and then see the op run produce something. Certainly better than the opposite with the op run blowing up a fantasy storm in an unfavorable pattern.

[Damage In Tolland]

Yeah, I think the OP runs are starting to see the ferocity of that block...esp the Euro which had been sort of ignoring it on its OP run for a few in a row, but now its gone a cooler/stormier look in the long range.

Yeah that's been my thinking . There is just no way a cutter plows into that block like Socker thought..you have to redevelop a 2ndary ..no way you don't

[CT Rain]

Yeah that's been my thinking . There is just no way a cutter plows into that block like Socker thought..you have to redevelop a 2ndary ..no way you don't

Well the reason it was showing the cutter was because the closed low retrograded so far you got this mammoth trough that dug in the central Plains. Looked way too extreme but that's what they were doing to get it.