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Winter 2018-19 Medium/Long Range Discussion


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32 minutes ago, Angrysummons said:

There may be a phasing chance/trough on the 21st(most EPS suites have it in some form, but pretty warm), but the STJ is overpowering right now and the northern stream pretty weak. Even if a system comes together, it may just be a bunch of rain(again). We are all waiting for the pacific to gets it act together................impatiently.

Wrong. Three feet of snow, winds of eighty million mph... (/s :))gfs_mslp_pcpn_frzn_us_26.png

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The ensembles definitely got worse the last week of December than what they had been showing for quite a while. Possible it's MJO influence which is forecast to be in phase 5 at that time, generally a warm phase for eastern US. OTOH, MJO can muck up long range predictability too.

 

The big talk has been the assault on the stratospheric polar vortex, but perhaps the lag effects of this take us into January. Hopefully there will be some effects of the warming in stratosphere toward the NAO/AO domain being undermodeled w.r.t. there being more blocking and heights being kept lower in the east than shown verbatim on the ensembles.

 

The main message is that the big -EPO that seemed to be highly likely doesn't appear to be coming back in December as things stand right now but with the large swings in LR this week, perhaps things are more uncertain than the normal uncertainty that far out. Pattern could be relatively active so it's possible some of us thread the needle and get some snow out of it. Certainly will need to watch the Thursday-Friday system for location and timing of phasing. Big signal for that system in the h5 anomalies.

 

 

 

 

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1 hour ago, RCNYILWX said:

The ensembles definitely got worse the last week of December than what they had been showing for quite a while. Possible it's MJO influence which is forecast to be in phase 5 at that time, generally a warm phase for eastern US. OTOH, MJO can muck up long range predictability too.

 

The big talk has been the assault on the stratospheric polar vortex, but perhaps the lag effects of this take us into January. Hopefully there will be some effects of the warming in stratosphere toward the NAO/AO domain being undermodeled w.r.t. there being more blocking and heights being kept lower in the east than shown verbatim on the ensembles.

 

The main message is that the big -EPO that seemed to be highly likely doesn't appear to be coming back in December as things stand right now but with the large swings in LR this week, perhaps things are more uncertain than the normal uncertainty that far out. Pattern could be relatively active so it's possible some of us thread the needle and get some snow out of it. Certainly will need to watch the Thursday-Friday system for location and timing of phasing. Big signal for that system in the h5 anomalies.

 

 

 

 

 I am not too familiar with stratospheric warming, stratospheric assault on the polar vortex, etc, but I gather that this is good news (with a lag effect) for wintry weather down the road. So I am hoping this means a nice wintry January and February. By the dead of winter, even in mild or unfavorable patterns we can get snowstorms, but im talking deep winter. Even the torch-biased CFS is going colder than avg by mid January. In the meantime, with an active pattern returning in late December, I am sure some of us will be able to get snow out it regardless of the lack of true cold.

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 I am not too familiar with stratospheric warming, stratospheric assault on the polar vortex, etc, but I gather that this is good news (with a lag effect) for wintry weather down the road. So I am hoping this means a nice wintry January and February. By the dead of winter, even in mild or unfavorable patterns we can get snowstorms, but im talking deep winter. Even the torch-biased CFS is going colder than avg by mid January. In the meantime, with an active pattern returning in late December, I am sure some of us will be able to get snow out it regardless of the lack of true cold.

I'm still learning stratosphere stuff myself, but it *should* be good news for the eastern US. There are cases when the SPV split or displacement evolution favors Eurasia for cold, though from what I've been reading that is not expected to be the case with this. Last February, the vortex split had a major role in the very wintry March and April in the east. Not everyone benefitted from major snows but there were certainly multiple opportunities in the sub.

 

Definitely a wait and see on the pattern for the last week of December. Right now it's kind of an ugly look on the ensemble means. Really hoping for some blocking and there being some cold around so that favorably tracked systems give snow chances for some of us.

 

 

 

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It's funny...a positive EPO was modeled for the middle of November and that didn't pan out at all, instead, we went back to the seemingly new normal this decade of a large ridge up there that gave most of the eastern US a cold second half of November and first part of December.  And completely blew my generally mild November call...  The very positive EPO for the middle and latter portions of December that was modeled as early as around Thanksgiving isn't going to fail.  When I saw the ensembles last week retracting the Pacific jet the last 10 days of December and beginning to really pump the ridge over AK I thought we'd go back to the familiar AK ridging pattern with maybe just a 7-10 day warm up, but I think in this instance the intensity of the current +WPO/EPO and unfavorable MJO is causing this milder period to pan out much closer to conventional wisdom...usually a massive +EPO/WPO is bad for sustained cold for most of the CONUS and takes some time to overcome, and that appears to be the case here.

With that said I do think this will be a delayed but not denied situation and is quite in line with many winter forecasts highlighting the second half of winter as the colder half.  The MJO will likely pass out of the unfavorable phases by the middle of January and a fact that many wish to forget is that SSWs usually have a lag effect as Ricky has alluded to...it's usually at least a week or two before tropospheric impacts are felt...that would put us around the second week of January.  Remember that a massive torch occurred in conjunction with last winter's SSW before we fell into a colder/blockier pattern a couple of weeks later in March.  I think the potential for both the tropics and stratosphere to work together could cause a wicked cold pattern at some point later January into February, though let's make sure we get a SSW first (it looks fairly likely, but it's still pretty far out).  In all likelihood that would eventually suppress things too much for much of this sub-forum's liking, but is still a few weeks away. 

In the meantime, the MJO passing through phases 4-6 and a drop in the AAM (note the large low dropping down east of the moutains in Asia, that's a negative mountain torque that will drop the AAM some) actually argues for a bit of a La Nina look the rest of this month, with an attempt at a SE ridge as the ensemble means want to show.  So there could be a conducive storm track for the Midwest and Great Lakes through the rest of December and into early January, but the cold will generally be iffy so we'll see how much of it ends up as snow. 

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Great post. I've seen it debated whether a true by the book SSW will occur but that a vortex split is still likely either way with tropospheric effects to come later. Though in recent days have seen increased confidence among strat experts that a true SSW will occur. I think there's a lot of merit to your idea of delayed but not denied with the deep cold.

In the interim, I'm seeing on the 12z GEFS some dateline ridging around Christmas, so the hope is that the Niña like state you referenced will have workable cold around the region with western troughing and southeast ridging leading to a decent storm track. The possibly nice thing during then is lack of a big time AK vortex with ridging out by the Aleutians.

EPS and GEFS are not too dissimilar earlier on in Christmas week but the 00z EPS reverts to a more strongly +EPO look with AK/GOA vortex more quickly than GEFS. Might be at least a few trackable threats that period before pattern becomes more hostile again?

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Good posts guys.  Does look like a La Nina flavor to the pattern and sustained wintry conditions may be hard to come by for a bit (except perhaps northern tier).
Perhaps some similarities to late December 2012 for a time with the temporary Nina like state coming despite that year being a cold neutral. Wasn't any deep cold around but had 2 major events (12/20-21) and the 26th in an otherwise mild +EPO month. f13fa0aa2f98bf68240922125b5228cd.gif

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1 hour ago, Chinook said:

I will be flying across the country to a certain Great Lakes city on Friday 12/21, and the newest GFS forecast has 977mb near that city, with a very large array of rain and some snow in the GL/OV. I wonder if I will have any flight delays. 977mb is notable.

I too am flying to a certain Great Lakes city that afternoon. Perhaps we'll share the same flight? 

Either way it doesn't look to have a ton of support for any snow chances, but sometime to at least watch. Pattern does get relatively active though no clear snow threats for now. 

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3 hours ago, OHweather said:

It's funny...a positive EPO was modeled for the middle of November and that didn't pan out at all, instead, we went back to the seemingly new normal this decade of a large ridge up there that gave most of the eastern US a cold second half of November and first part of December.  And completely blew my generally mild November call...  The very positive EPO for the middle and latter portions of December that was modeled as early as around Thanksgiving isn't going to fail.  When I saw the ensembles last week retracting the Pacific jet the last 10 days of December and beginning to really pump the ridge over AK I thought we'd go back to the familiar AK ridging pattern with maybe just a 7-10 day warm up, but I think in this instance the intensity of the current +WPO/EPO and unfavorable MJO is causing this milder period to pan out much closer to conventional wisdom...usually a massive +EPO/WPO is bad for sustained cold for most of the CONUS and takes some time to overcome, and that appears to be the case here.

With that said I do think this will be a delayed but not denied situation and is quite in line with many winter forecasts highlighting the second half of winter as the colder half.  The MJO will likely pass out of the unfavorable phases by the middle of January and a fact that many wish to forget is that SSWs usually have a lag effect as Ricky has alluded to...it's usually at least a week or two before tropospheric impacts are felt...that would put us around the second week of January.  Remember that a massive torch occurred in conjunction with last winter's SSW before we fell into a colder/blockier pattern a couple of weeks later in March.  I think the potential for both the tropics and stratosphere to work together could cause a wicked cold pattern at some point later January into February, though let's make sure we get a SSW first (it looks fairly likely, but it's still pretty far out).  In all likelihood that would eventually suppress things too much for much of this sub-forum's liking, but is still a few weeks away. 

In the meantime, the MJO passing through phases 4-6 and a drop in the AAM (note the large low dropping down east of the moutains in Asia, that's a negative mountain torque that will drop the AAM some) actually argues for a bit of a La Nina look the rest of this month, with an attempt at a SE ridge as the ensemble means want to show.  So there could be a conducive storm track for the Midwest and Great Lakes through the rest of December and into early January, but the cold will generally be iffy so we'll see how much of it ends up as snow. 

Always enjoy reading your thoughts OH Weather even know a big chunk of it is way over my head and I don't understand it to well but I think I get the point. Looking like no real sustained cold for most of our sub forum for another 3-5 weeks and what systems we do have come through our sub will more then likely be wet and not white except for the far northern and western areas. That's pretty much what Jon Dee is saying also, wet for most with some white stuff possible in the far north and west between now and the new year. 

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1 hour ago, AppsRunner said:

I too am flying to a certain Great Lakes city that afternoon. Perhaps we'll share the same flight? 

Either way it doesn't look to have a ton of support for any snow chances, but sometime to at least watch. Pattern does get relatively active though no clear snow threats for now. 

Oh yeah, that's right, you are the one from Toledo OH also. Oh well, for what it's worth, I never get a fight to Toledo, because it's too expensive to fly to a minor airport. I am also glad that I am not planning to drive 1200 mi to Ohio any time soon.

As a result of some of these drives, I have a lot of interest in severe storms and bad weather all along I-80.

I have invented a name for I-80/I-294 in south Chicago area. (Hammond, IN, South Holland IL) I call it "Traffic Canyon." Traffic flows pretty smoothly with so many lanes.

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39 minutes ago, slow poke said:

Always enjoy reading your thoughts OH Weather even know a big chunk of it is way over my head and I don't understand it to well but I think I get the point. Looking like no real sustained cold for most of our sub forum for another 3-5 weeks and what systems we do have come through our sub will more then likely be wet and not white except for the far northern and western areas. That's pretty much what Jon Dee is saying also, wet for most with some white stuff possible in the far north and west between now and the new year. 

I'm sure each storm will have an area of snow it's all going to depend on track. It is not a torch pattern where only the far North and West can get  Snow

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