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SE Mid-Long Range Discussion II


strongwxnc

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Here's what a met said on front page in the medium range about ensembles. FWIW

Nice map, but the EURO ensembles show no such thing (much more zonal). This is 2 days in a row with that nice 240 hour tease from the operational EURO.

Yeah, not sure if he's referring to the Euro Ens Mean or the individual members. The mean looked fine in my view. Alaska low is gone and replaced with tall ridging. AO and NAO slightly negative. As you go out in time, everything gets smoothed out on an ensemble mean and you're not going to see the extremes like you are in an op run. The positive feature right now that we have been seeing with consistency is the tall ridging in the vicinity of Alaska.

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Ok, so I said I didnt really care about past day 7, but that's a pretty big anomaly showing up with the Alaskan blocking............ to be at day 10. Very strong signal. I guess where it sets up will mean all the difference in the world.

I thought you might like it, so I included it for you. :) For an ensemble image the force is strong with this one.

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Yeah, not sure if he's referring to the Euro Ens Mean or the individual members. The mean looked fine in my view. Alaska low is gone and replaced with tall ridging. AO and NAO slightly negative. As you go out in time, everything gets smoothed out on an ensemble mean and you're not going to see the extremes like you are in an op run. The positive feature right now that we have been seeing with consistency is the tall ridging in the vicinity of Alaska.

Gotcha, I'm like you I do like the consistency of that tall ridging showing up.

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Ok, so I said I didnt really care about past day 7, but that's a pretty big anomaly showing up with the Alaskan blocking............ to be at day 10. Very strong signal. I guess where it sets up will mean all the difference in the world.

Indeed it is. I think we will see that blocking up there but still a big question where the pieces fall downstream. the 18z run starts to bring a cold outbreak then stalls it, then retreats it north, so that most of the country is warm by the end of the run. Has zonal flow. Thats an option I guess, but I don't recall seeing an outbreak do like that. Usually when a huge chunk of arctic air gets on the move, it's hard to stop it. Usually if we miss it, it's only because it dumped totally in the west or Pacific. Thats more likely than the zonal flow the 18z shows. IMO.
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The Alaskan block looks like it moves towards the west and then it's more of a Siberian block at that point.... and thus the cold never gets to the CONUS.

Interesting, let's put a huge trough, right where we had a huge ridge in alaska on the models just 6 hours earlier.

No problem, dump this run and press forward. (and before anyone asks..........yes, b/c it doesn't show what I want) haha

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Interesting, let's put a huge trough, right where we had a huge ridge in alaska on the models just 6 hours earlier.

No problem, dump this run and press forward. (and before anyone asks..........yes, b/c it doesn't show what I want) haha

That's fine with me.. It's gonna change many times good and bad lol...

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ORH_wxman, Wes, and Don S. not really to positive on the cold in the east, or at least sustained cold, from what I understand!

ORH_wxman-- it definitely looks like we will be entering a -PNA period for the latter part of January and probably into February. GEFS are trying to keep it more positive but I think that flies in the face of typical Nina/-PDO climo and flies in the face of the Euro ensembles which have it going negative. A flexed Aleutian ridge teleconnects pretty good to a -PNA as well.

Then Wes--- plus usually when you get high latitude ridging it retrogrades to the west which also would favor a -PNA. The cross polar flow means more cold air should get into the conus but it likely will be aimed west. You guys could do OK, south of 40N I could see us still staying warm even with move shots of cold air.

Don S.--- PDO- winters have a higher frequency of PNA- than PDO+ ones (SSTAs being the driver). MJO can't be forecast that far out. Also the period of blocking that seems to be increasingly likely looks to be the result of the polar vortex's being displaced not split. Normal to somewhat below average Siberian snow cover also argues against an AO- winter. EPO is shown as returning to somewhat positive levels on some of the guidance e.g., 0z GFS ensembles.

So many conflicting thoughts I don't think you can trust any models past day 5....

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the 18z GFS ensemble mean doesn't look bad. Stays seasonal to slightly below with precip chances here and there in the Mid and long range. Especially looks good at 180. There must be some individual members with a good look at that time frame for some of us.

I'm not worried with one completely opposite 18z GFS operational run but I know anything can happen of course.

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Then Wes--- plus usually when you get high latitude ridging it retrogrades to the west which also would favor a -PNA. The cross polar flow means more cold air should get into the conus but it likely will be aimed west. You guys could do OK, south of 40N I could see us still staying warm even with move shots of cold air.

Great article from Wes today on the current situation posted over in the midatlantic forum..

http://www.washingtonpost.com/blogs/capital-weather-gang/post/a-pattern-change-probably-yes-but-what-it-means-for-dc-uncertain/2012/01/06/gIQAKgcWfP_blog.html#pagebreak

Wes is unassuming, humble etc but is as good a met as there is on the board or off...

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Great article from Wes today on the current situation posted over in the midatlantic forum..

http://www.washingto....html#pagebreak

Wes is unassuming, humble etc but is as good a met as there is on the board or off...

Agreed Mr. Bob!!! He is fantastic and you always have to pay attention to where he stands. He is part of the reason I made a post about being on the fence earlier.

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Indeed it is. I think we will see that blocking up there but still a big question where the pieces fall downstream. the 18z run starts to bring a cold outbreak then stalls it, then retreats it north, so that most of the country is warm by the end of the run. Has zonal flow. Thats an option I guess, but I don't recall seeing an outbreak do like that. Usually when a huge chunk of arctic air gets on the move, it's hard to stop it. Usually if we miss it, it's only because it dumped totally in the west or Pacific. Thats more likely than the zonal flow the 18z shows. IMO.

An Arctic air mass can "stall" if the AK block gets too closed off and then the cold air will dive SW into the EPAC and the strong Pacific flow undercuts it. For a really cold air blast it is better to have a full latitude ridge than a closed upper high.

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At this point in time, the idea that the eastern half of the U.S., along with southern Ontario and Quebec, will see the first half of January average above to much above normal in terms of temperatures looks to be on track. The farther north one goes, the warmer the anomalies will be during this period in time.

Afterward, it appears that the major teleconnection indices will undergo a change. It still remains unlikely that the kind of regime change that is needed to bring and sustain severe cold in the areas experiencing the warmth is likely during the January 16-23 timeframe. The turn toward colder readings is likely to be gradual. As a result, much of the East will likely remain at least somewhat milder than normal during that timeframe, but pockets of near normal readings, particularly in the Southeast may occur courtesy of a transient cold shot. Stronger and more sustained cold might be building into the Northern Plains from western Canada and that could be sufficient for that part of the U.S. to have colder than normal readings for the period.

Here are the temperature anomalies for all days during January 15-25 period (1950-2011) during La Niña events with ENSO R3.4 anomalies in the -1.5°C to -0.7°C range, AO in the -2.00 to 0.00 range and PNA in the -1.00 to +0.25 range:

Jan16232012All.gif

If one looks at the objective analogs generated by the GFS ensembles (centered around 1/17), among the years showing up are 1954 and 1984. Both years saw very warm February anomalies. The raw temperature data for all the years generated saw February have a mean temperature that was close to normal in the Mid-Atlantic region. However, if one adjusts the readings for the observed warming that has occurred by standardizing the base period to the current one (1981-10), the outcome was 1°-2° above normal.

Both the GFS and ECMWF take the MJO through Phase 8 (ECMWF keeps it weak and in the so-called "circle of death"). The GFS goes into Phase 1. If the timing on the GFS is correct and if the MJO progresses at a fairly average pace with no "short cuts" or reversals--two big "ifs"--the MJO could return to Phase 4 sometime during the first 7-10 days in February. Phases 4-7 are typically warm in the East, with Phases 6-7 being cold in the West (typical PNA- pattern). The bottom line is that the MJO forecasts might also be offering a hint of a plausible warm outcome in February.

The CFSv2 ensemble system is also hinting at a warm outcome in February. Run-to-run continuity has been very good for North America.

The actual outcome for February will depend on the continuing evolution of the La Niña and the teleconnections. For now, there are some hints from the objective analogs and also MJO forecasts that a mild February, at least in the East, is a possibility. Things can still change, as February is well in the future. What does appear to be a higher confidence idea is that even after mid-month, the January 16-23 timeframe will likely see milder readings outduel cooler ones in areas that are likely to have been warm to very warm during the first half of this month.

Yikes...Don S. update..lI kept waiting for the good news, it never came.

http://www.americanw...2/page__st__420

I was just getting ready to post that over here. Anyway here it is. We'll have to wait and see how this all turns out.

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Well the winter is not over by any means but things look to be stacked against use. The MJO,Blocking, La Nina, ect.Well there are still a couple month to go but spring may come early.

I wouldn't say that because the AO and NAO are going to have to switch at some point. If it switches over in late March for example then we would have a cold and rainy spring. Eyewall mentioned this yesterday. Anyway that's getting ahead of ourselves though. Let's see what ends up happening first.

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