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December 2012 Pattern Analysis


HailMan06

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LOL, well it may prevent a few places from having their warmest December on record. Nobody in the Northeast will really come close, however, there are quite a few big cities in the Midwest/TN Valley and south that have remarkably good chances right now, as a matter of fact some places like MEM/ATL/BHM are on pace to absolutely annihilate 1984 right now, even with a near normal rest of the month they'd have it beat by a reasonable margin.

I was looking at 1912-13 as a possible analog and there are some similarities...The mei looks very similar...The jma looks similar...NYC had a snowfall in November and a major snowstorm Christmas eve...A torch January...Cold February...Not much snowfall after the 12/24 storm...

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Euro now has the big ULL from the mid-week system cutting off underneath a block to the north. Sits over the Northeast through Day 7. -12C 850 temperatures on Sunday.

And now, what appears to be a storm threat developing for Christmas or Boxing Day in the long range.

Getting the late week inland-runner short wave to cut-off to our NE is absolutely crucial in setting the stage for any wintry threat that follows. If it doesn't cut off and just continues on its merry way into the north atlantic - say hello to wash, rinse, repeat w/ the mid level ridging building out ahead of the Christmas short wave. The cut-off in SE Canada would maintain confluence and keep the cold air readily available across the northern tier.The short wave ejecting from the Pacific would have no choice but to cut due east to the mid atlantic coast if that monster 50/50 type low remains in place.

Folks also have to understand that we want this late week inland runner as strong as possible. Weak lows that transfer east of New England do zero work in setting up a 50/50 or forcing the Canadian polar air into the northern tier. We want a bombing low to finally rid this putrid airmass that's been plaguing the East so far this December.

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FWIW the 12z JMA goes towards EURO & closes the low off way farther south compared to GFS.

I wonder if this trend will continue and we get redevelopment farther south. Maybe some backlash snowshowers? Can't tell how much precip would fall after this frame since the JMA graphics suck...

REMEMBER, most of the precip falls with the warm front before the low closes off east.

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post-8091-0-11408900-1355688468_thumb.gi

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The 12z Euro ensemble actually looks rather similar to the JMA, closing off the Friday low sooner and further east than the operational run, although not quite as quick or far east as the JMA. Not that it will make any difference, but if by any chance this trend continued, it might make a difference.

post-1914-0-52128300-1355691727_thumb.gi

post-1914-0-73692600-1355691747_thumb.gi

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Getting the late week inland-runner short wave to cut-off to our NE is absolutely crucial in setting the stage for any wintry threat that follows. If it doesn't cut off and just continues on its merry way into the north atlantic - say hello to wash, rinse, repeat w/ the mid level ridging building out ahead of the Christmas short wave. The cut-off in SE Canada would maintain confluence and keep the cold air readily available across the northern tier.The short wave ejecting from the Pacific would have no choice but to cut due east to the mid atlantic coast if that monster 50/50 type low remains in place.

Folks also have to understand that we want this late week inland runner as strong as possible. Weak lows that transfer east of New England do zero work in setting up a 50/50 or forcing the Canadian polar air into the northern tier. We want a bombing low to finally rid this putrid airmass that's been plaguing the East so far this December.

The danger with the fast Pacific flow is that the 50/50 gets dislodged by the kicker moving into the

West and Central states around 10 days out. The Euro is still showing a parade of storms coming

into the West Coast.

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Yes. But the GEFS still has higher heights across the AK region. And maintains a cross-polar longer than Euro ensemble mean. A system will break away from the NE Pacific trough, sometime between 25-27th. If we still have the cross-polar flow and the west-based -NAO in place, we can see snow.

The GEFS has higher heights over Northern Alaska, but there is still too much energy digging in

along the West Coast with the tendency to pump the SE Ridge and WAA into our area in the

wake of the departing cooler airmass. We would like to see more ridging extending all along

the West Coast in later runs for a significant snow threat here.

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Yep. Remember how this map was full of red last year. What a disaster it was.

We'll see if the bulk of the Arctic air holds on over Western Canada or we can get a piece

to break off and drop into the Western or Central US initially. I guess it will depend on how

EPO behaves later this month into January.

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The GEFS has higher heights over Northern Alaska, but there is still too much energy digging in

along the West Coast with the tendency to pump the SE Ridge and WAA into our area in the

wake of the departing cooler airmass. We would like to see more ridging extending all along

the West Coast in later runs for a significant snow threat here.

I think the smoothing out ensemble means this far out, make it looks worse than it will be. We can also overwhelm the -PNA or pacific jet, with a Aleutian/AK bridge or big block over Central Canada.

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Let me first make clear that there is no big winter nut than I however I don't thnk what we are about to see is that hard to pick out pls go to your favorite model site and toggle thru the " north America wide " 500 -mb pattern over the next 10 days and u will see what's obvious.

Right out off the west coast u see a beautiful " ugly " ridge to the east of Catalina , That has bad intentions for us , what happens is a dry ULL stalls for a few days in the NE so it's cold and dry for several days. , however it gets scurried out in the end because that PAC trof pulls the ridge axis back.

So when I keep reading " The signal is there for post Xmas " I Tell myself yeh if I lived in Chicago . That ULL and atlantic are powerless against the pacific. You have understand that trof axis is on a string. It gets let out a bit but has to pull back as the PAC ridge retrogrades The atlantic is like a little kid in a heavy weight fight. The NAO dips every time a system rolls thru but rises again as the ridge pops. any system christmas week has a Better than equal chance of cutting because that west coast pulls our trof back and that west coast trof is being being controlled by that PAC ridge. That's a real. Teleconnections So every time u see these fantasy snowstorms 10 12 15 days out. Ask ur self what's diff in the pacific and so far nothing

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In short That day 10 ridge axis is too far into the pacific to allow that trof to the east coast so the model turn it in the mid section where it should naturally turn. The speed and placement of the pacific determines if a storm comes under " any " block or if it routes it out

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No calling off of winter here , just a week after the next cool down. I tend to focus on no more than 10 days at a time So I hope no one takes my posts as the end all be all. I base my opinions on the PAC , it's not gona stay like ths for the next 8 weeks. Just goin out 10 days. Call off the dogs

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I was looking at 1912-13 as a possible analog and there are some similarities...The mei looks very similar...The jma looks similar...NYC had a snowfall in November and a major snowstorm Christmas eve...A torch January...Cold February...Not much snowfall after the 12/24 storm...

Off memory the Nhem anomalies overall reminded me somewhat of 90-91. I believe 90-91 was largely a cold winter in the Nhem but not over NOAM minus the Western U.S. I think Europe had one of their snowier and colder winters on record but the Pac overwhelmed the US.

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One nice sign I see this morning of note is by Day 10 the core of the coldest air in Canada shifts slightly eastward away from Alaska which asscoaited with that main PV .

That may accomplish 2 things , it may allows the possibility of higher heights to nose its way into alaska and it forces the main piece of the PV further west so that core of the cold gets forced south into the upper midwest and great lakes not not down the west coast .

Now it will be a matter of ,can u get the PAC to temporary build ridging into alaska so theres a continued forcing of the main PV west from over the top of the pole If you build a block the cold air slides underneath .

Trying to figure out what more tempermental Modeling or Wives .

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0z Euro was pretty awful...

Notable differnce PV is in Central Canada on 0z , was back over Alaska on yesterdays 12z

So , theres a chance that next weeks system doesnt cut like i thought last nite , because the ridge is over the rockies this morning and not east of Cali .That argues for a system east of the MTNS .

Pretty big swing in 12 hrs

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Notable differnce PV is in Central Canada on 0z , was back over Alaska on yesterdays 12z

So , theres a chance that next weeks system doesnt cut like i thought last nite , because the ridge is over the rockies this morning and not east of Cali .That argues for a system east of the MTNS .

Pretty big swing in 12 hrs

I guess the big question is can we even trust the colder looking Euro ensemble mean from this far

out when the warm events this week at some point were modeled colder also? We could see a shift

further east in the mid-range only to trend warmer the closer we get to the event.

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I guess the big question is can we even trust the colder looking Euro ensemble mean from this far

out when the warm events this week at some point were modeled colder also? We could see a shift

further east in the mid-range only to trend warmer the closer we get to the event.

I would just like to see 2 or 3 model runs that have some similarities . And I dont mean individual systems , but the up and downstream players are moving like crazy , so its fuzzy from here .

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I would just like to see 2 or 3 model runs that have some similarities . And I dont mean individual systems , but the up and downstream players are moving like crazy , so its fuzzy from here .

Yeah, it would be nice if the Euro ensemble mean was onto something and held serve without

trending further west in time.

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I guess the big question is can we even trust the colder looking Euro ensemble mean from this far

out when the warm events this week at some point were modeled colder also? We could see a shift

further east in the mid-range only to trend warmer the closer we get to the event.

The Euro ensemble is starting picking up cut off block near Alaska between 120-168hr. That's going to help sustain the cross-polar flow, if it's correct.

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I guess the big question is can we even trust the colder looking Euro ensemble mean from this far

out when the warm events this week at some point were modeled colder also? We could see a shift

further east in the mid-range only to trend warmer the closer we get to the event.

I wouldn't bet on it from this far out...It's funny that lousy winters have great patterns 10 days out and good winters much sooner...

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GFS and Euro both continue to advertise increasing cold in the post 12/21 time frame. The vortex over AK continues to move and break down as higher heights and meridial flow dominate the arctic and allow for plenty of cold down into the northeast

It looks like we're going to cool down to near normal for a little while before another major storm heads well to our west. I really do believe that we are still at least a few weeks away from any significant wintry precipitation threats.

WX/PT

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