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Winter 2020-21 Medium/Long Range Discussion


Hoosier
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Link to a loop of the ECMWF weeklies run last night for the 00z/28 cycle: https://33andrain.s3.amazonaws.com/monthly_2020_12/ecmwf-weeklies-avg-nhemi-z500_anom_7day-1609113600-1609718400-1613088000-20.gif.64969e182ab9478fa5381e7fe5f284d5.gif

Not sure if it'll work. Tried to post the .gif but file size is too big.

In sum, the ++EPO Pac puke dominated start to January goes over to an Atlantic and Arctic blocking dominated pattern. The latter portions of recent ensemble runs also going to that sort of look. Been a lot of discussion on SSW likelihood into January. Certainly don't want to hype it like it often gets, but long range experts are saying there's good precursors going on near Siberia to favor the occurrence. If so, the tendency for -AO/-NAO that's been there could further deepen and point toward a colder outcome than expected from mid January or thereabouts and probably into Feb.

If a major anomalous blocking episode develops, they tend to stick around for quite a while. For most recent met winters that had deep Arctic and Atlantic blocking in the heart of the winter, have to go all the way back to 2009-10 and 2010-11. The 09-10 block lasted all the way through Feb and into March, but the 10-11 block collapsed in early Feb (and probably helped those of us who cashed in on GHD I). After a mild start to January, things "could* turn more interesting if we get cooperation from the Pacific. We'll see how things play out as we get closer to that period.

Sent from my SM-G965U using Tapatalk

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4 minutes ago, RCNYILWX said:

Link to a loop of the ECMWF weeklies run last night for the 00z/28 cycle: https://33andrain.s3.amazonaws.com/monthly_2020_12/ecmwf-weeklies-avg-nhemi-z500_anom_7day-1609113600-1609718400-1613088000-20.gif.64969e182ab9478fa5381e7fe5f284d5.gif

Not sure if it'll work. Tried to post the .gif but file size is too big.

In sum, the ++EPO Pac puke dominated start to January goes over to an Atlantic and Arctic blocking dominated pattern. The latter portions of recent ensemble runs also going to that sort of look. Been a lot of discussion on SSW likelihood into January. Certainly don't want to hype it like it often gets, but long range experts are saying there's good precursors going on near Siberia to favor the occurrence. If so, the tendency for -AO/-NAO that's been there could further deepen and point toward a colder outcome than expected from mid January or thereabouts and probably into Feb.

If a major anomalous blocking episode develops, they tend to stick around for quite a while. For most recent met winters that had deep Arctic and Atlantic blocking in the heart of the winter, have to go all the way back to 2009-10 and 2010-11. The 09-10 block lasted all the way through Feb and into March, but the 10-11 block collapsed in early Feb (and probably helped those of us who cashed in on GHD I). After a mild start to January, things "could* turn more interesting if we get cooperation from the Pacific. We'll see how things play out as we get closer to that period.

Sent from my SM-G965U using Tapatalk
 

you're not the only one that's mentioned the tendency for anomalous high lat blocking to sit around for many weeks/months. I've seen that elsewhere too. Those same people also think the current pattern evolution resembles that of 09-10 and 10-11 closely. One can only hope as the thing that the current pattern needs most is a little more cold air to work with.

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9 hours ago, RCNYILWX said:

Link to a loop of the ECMWF weeklies run last night for the 00z/28 cycle: https://33andrain.s3.amazonaws.com/monthly_2020_12/ecmwf-weeklies-avg-nhemi-z500_anom_7day-1609113600-1609718400-1613088000-20.gif.64969e182ab9478fa5381e7fe5f284d5.gif

Not sure if it'll work. Tried to post the .gif but file size is too big.

In sum, the ++EPO Pac puke dominated start to January goes over to an Atlantic and Arctic blocking dominated pattern. The latter portions of recent ensemble runs also going to that sort of look. Been a lot of discussion on SSW likelihood into January. Certainly don't want to hype it like it often gets, but long range experts are saying there's good precursors going on near Siberia to favor the occurrence. If so, the tendency for -AO/-NAO that's been there could further deepen and point toward a colder outcome than expected from mid January or thereabouts and probably into Feb.

If a major anomalous blocking episode develops, they tend to stick around for quite a while. For most recent met winters that had deep Arctic and Atlantic blocking in the heart of the winter, have to go all the way back to 2009-10 and 2010-11. The 09-10 block lasted all the way through Feb and into March, but the 10-11 block collapsed in early Feb (and probably helped those of us who cashed in on GHD I). After a mild start to January, things "could* turn more interesting if we get cooperation from the Pacific. We'll see how things play out as we get closer to that period.

Sent from my SM-G965U using Tapatalk
 

Hopefully it would yield a good clipper pattern. Im all for a clipper parade and cold. We've had 3 snowfalls of 3-4" so far which us better than many, but each only lasted on the ground 3-4 days.  If it's going to be smaller snows, let's add them up. If it's going to snow melt snow melt snow melt, let's get a big one.

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7 hours ago, Angrysummons said:

Oh come on. 10 and 11 this isn't. Matter of fact, the "high latitude blocking" is why the pacific is in such a dogsheet condition right now. Its basically a witch's -ao/nao. Smiling at you with a crooked grin.

I didn't say it was. I said that people had also used those years as examples of how high lat blocking can linger, and that Ricky was not the only one thinking that.

 

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On 12/29/2020 at 3:10 AM, RCNYILWX said:

Link to a loop of the ECMWF weeklies run last night for the 00z/28 cycle: https://33andrain.s3.amazonaws.com/monthly_2020_12/ecmwf-weeklies-avg-nhemi-z500_anom_7day-1609113600-1609718400-1613088000-20.gif.64969e182ab9478fa5381e7fe5f284d5.gif

Not sure if it'll work. Tried to post the .gif but file size is too big.

In sum, the ++EPO Pac puke dominated start to January goes over to an Atlantic and Arctic blocking dominated pattern. The latter portions of recent ensemble runs also going to that sort of look. Been a lot of discussion on SSW likelihood into January. Certainly don't want to hype it like it often gets, but long range experts are saying there's good precursors going on near Siberia to favor the occurrence. If so, the tendency for -AO/-NAO that's been there could further deepen and point toward a colder outcome than expected from mid January or thereabouts and probably into Feb.

If a major anomalous blocking episode develops, they tend to stick around for quite a while. For most recent met winters that had deep Arctic and Atlantic blocking in the heart of the winter, have to go all the way back to 2009-10 and 2010-11. The 09-10 block lasted all the way through Feb and into March, but the 10-11 block collapsed in early Feb (and probably helped those of us who cashed in on GHD I). After a mild start to January, things "could* turn more interesting if we get cooperation from the Pacific. We'll see how things play out as we get closer to that period.

Sent from my SM-G965U using Tapatalk
 

Supposedly the SSW is underway. I look forward to your analysis as we get closer to mid January.  There's one crowd that will see snow and cold no matter where they look and there's another crowd that sees torches, futility, and screw jobs wherever they look. It's the non biased analysis like you that I especially look forward to!

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8 minutes ago, Hoosier said:

I cringe a little at SSW talk.  Sure, it can help the pattern, but there is no guarantee it benefits our part of the globe.

oh for sure. just as I cringe at talk of futility and thinking a bad pattern will never end lol. there's also talk of -nao and blocking. it would seem to me that colder is very likely as we head to the dead of winter, but so many players involved in what the actual pattern will be. suppression? clippers? ghdiii? time will tell but the possibilities are many.

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52 minutes ago, Hoosier said:

I cringe a little at SSW talk.  Sure, it can help the pattern, but there is no guarantee it benefits our part of the globe.

I agree. If anything, it may help snow weenies out in the Mid-Atlantic with such an impressive west based -NAO. But for us, I don't foresee any 2014 or 2015 type of cold if the vortex remains parked up in AK. 

However, it should help in increasing snowfall probabilities as we'll have more cold air to work with than now. 

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The very strong positive East Asian Mountain Torque (the very strong high pressure over eastern Asia) which is causing our strong Pacific jet stream and flood of mild air, but is also contributing to the developing strat warming event, is hinted to begin weakening in the the 7-10 day:

 

ecmwf-ens_mslpa_global_fh0-240.thumb.gif.8422b1bd5f22130aeb5aff11a29cdde3.gif

 

This causes the trough to begin retrograding across the northern Pacific as the Pacific jet begins to pull back a bit. As a result, both the GEFS and EPS begin raising heights in the 10-15 day range on the West Coast of the US and Canada:

622606883_GEFS5005-15.thumb.png.981dcc572d68d73bc20b3a4621916299.png

1277310806_EPS5005-15.thumb.png.0277163fd37961ce2d5979cf5b992aa8.png

With an active sub-tropical jet and developing split flow over the western U.S., along with a persistent, west-based -NAO, this would begin increasing the risk for winter storms across the eastern and central U.S. around or just after January 10th. It would not immediately be a very cold pattern, but it could be a snowy one for some areas. 

The EPS continues to retrograde the trough into northeast Asia in the 10-15 day range while the Pacific jet continues pulling back. I'm not sure this lasts long, but could give a window for ridging into Alaska after mid-month. With a split flow over the western US and continued -NAO, a window of ridging over Alaska could both introduce colder air, but also lead to a quite active pattern for the Ohio Valley and southern Great Lakes into the Northeast beginning around or just after the middle of January. 

14-km_EPS_Global_Globe_200_hPa_Wind_(1).gif.de6b65be41887373a5f8da892c5f0858.gif

 

This is still a long way's out, but signs point to a better Pacific pattern soon. Given the -NAO in place slowing down any storms over the eastern 2/3rds of the CONUS, all we need is a somewhat cooperative Pacific to have some fun. 

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17 minutes ago, OHweather said:

The very strong positive East Asian Mountain Torque (the very strong high pressure over eastern Asia) which is causing our strong Pacific jet stream and flood of mild air, but is also contributing to the developing strat warming event, is hinted to begin weakening in the the 7-10 day:

 

ecmwf-ens_mslpa_global_fh0-240.thumb.gif.8422b1bd5f22130aeb5aff11a29cdde3.gif

 

This causes the trough to begin retrograding across the northern Pacific as the Pacific jet begins to pull back a bit. As a result, both the GEFS and EPS begin raising heights in the 10-15 day range on the West Coast of the US and Canada:

imageproxy.php?img=&key=4c6452e0fc83486c622606883_GEFS5005-15.thumb.png.981dcc572d68d73bc20b3a4621916299.png

1277310806_EPS5005-15.thumb.png.0277163fd37961ce2d5979cf5b992aa8.png

With an active sub-tropical jet and developing split flow over the western U.S., along with a persistent, west-based -NAO, this would begin increasing the risk for winter storms across the eastern and central U.S. around or just after January 10th. It would not immediately be a very cold pattern, but it could be a snowy one for some areas. 

The EPS continues to retrograde the trough into northeast Asia in the 10-15 day range while the Pacific jet continues pulling back. I'm not sure this lasts long, but could give a window for ridging into Alaska after mid-month. With a split flow over the western US and continued -NAO, a window of ridging over Alaska could both introduce colder air, but also lead to a quite active pattern for the Ohio Valley and southern Great Lakes into the Northeast beginning around or just after the middle of January. 

14-km_EPS_Global_Globe_200_hPa_Wind_(1).gif.de6b65be41887373a5f8da892c5f0858.gif

 

This is still a long way's out, but signs point to a better Pacific pattern soon. Given the -NAO in place slowing down any storms over the eastern 2/3rds of the CONUS, all we need is a somewhat cooperative Pacific to have some fun. 

Always appreciate your knowledge & insight in LAMENS terms. Thank you!!!

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12 hours ago, OHweather said:

The very strong positive East Asian Mountain Torque (the very strong high pressure over eastern Asia) which is causing our strong Pacific jet stream and flood of mild air, but is also contributing to the developing strat warming event, is hinted to begin weakening in the the 7-10 day:

 

ecmwf-ens_mslpa_global_fh0-240.thumb.gif.8422b1bd5f22130aeb5aff11a29cdde3.gif

 

This causes the trough to begin retrograding across the northern Pacific as the Pacific jet begins to pull back a bit. As a result, both the GEFS and EPS begin raising heights in the 10-15 day range on the West Coast of the US and Canada:

imageproxy.php?img=&key=4c6452e0fc83486c622606883_GEFS5005-15.thumb.png.981dcc572d68d73bc20b3a4621916299.png

1277310806_EPS5005-15.thumb.png.0277163fd37961ce2d5979cf5b992aa8.png

With an active sub-tropical jet and developing split flow over the western U.S., along with a persistent, west-based -NAO, this would begin increasing the risk for winter storms across the eastern and central U.S. around or just after January 10th. It would not immediately be a very cold pattern, but it could be a snowy one for some areas. 

The EPS continues to retrograde the trough into northeast Asia in the 10-15 day range while the Pacific jet continues pulling back. I'm not sure this lasts long, but could give a window for ridging into Alaska after mid-month. With a split flow over the western US and continued -NAO, a window of ridging over Alaska could both introduce colder air, but also lead to a quite active pattern for the Ohio Valley and southern Great Lakes into the Northeast beginning around or just after the middle of January. 

14-km_EPS_Global_Globe_200_hPa_Wind_(1).gif.de6b65be41887373a5f8da892c5f0858.gif

 

This is still a long way's out, but signs point to a better Pacific pattern soon. Given the -NAO in place slowing down any storms over the eastern 2/3rds of the CONUS, all we need is a somewhat cooperative Pacific to have some fun. 

Great analysis!

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On 12/27/2020 at 3:28 PM, Chambana said:

After missing out another winter storm later this week, I’m in full punt mode on this winter. Im closing in on 6 years since my last 6”+ snowfall. I want an early spring, and a nice summer. 

I laugh, and cry at the same time.

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