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Winter 2020-2021


ORH_wxman
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19 minutes ago, 40/70 Benchmark said:

3 Coupling Between Tropical Width and Meridional Variations of MMTG

A fundamental driver of the atmospheric circulation is the meridional temperature gradient. Tropical expansion is associated with a poleward displacement of westerlies, jet streams, and storm tracks (Archer & Caldeira, 2008; Chen et al., 2008; Yin, 2005). These phenomena are all associated with the atmospheric meridional temperature gradients (Kaspi & Flierl, 2007; Lesieur et al., 2000; Sampe et al., 2010; Yang et al., 2019), raising the question of whether the displacement of the meridional temperature gradient is associated with the tropical width.

Given that the tropical width does not vary homogeneously over all ocean basins (Amaya et al., 2018), we examine the tropical width from a regional perspective. The annual‐mean tropical width over an individual ocean basin is calculated as a metric of the latitude where the near‐surface zonal wind changes from easterly to westerly in the subtropics (USF, see section 2). To get the corresponding pattern of SST gradient related to the wider tropics, we regress the USF indices of tropical width onto a field of absolute value of meridional SST gradients over their corresponding ocean basins (Figure 1). Both observations and model results from the CMIP5 exhibit a decrease of SST gradient over the latitude band between 25° and 40°, while an increase of SST gradient is found over the latitude band between 40° and 55°. Such features are notable across all ocean basins. The pattern illustrates that the wider tropics are linked to poleward displacement of the meridional SST gradient over the midlatitude area, that is, MMTG.

 

While the study corroborates John's assertion that the Hadley cell is expanding, it also acknowledges that it should be more prevalent across the southern hemisphere, where there is more ocean.

Interesting.

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Common denominator of '95-'96, '05-'06, and '07-'08 were all 3 had very good or excellent Decembers. The pattern differed though in how we achieved it....1995 was a big -NAO block and 2007 was literally the opposite...a monster +NAO vortex that actually was displaced far enough southwest that it was acting almost like a block in and of itself and producing a big gradient in the east where it was a massive torch in the mid-atlantic/southeast and pretty cold in New England. 2005 was mostly PAC-driven western ridging, though the NAO wasn't hostile.

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14 hours ago, uncle W said:

95-96....great winter...

05-06....good winter...

07-08...horrible winter...

I'll take a blend of all three....

So might I, but for much different opinions:

95-96...Lots of snow, lots of rain, lousy retention, fringed by the megalopolis bomb.

05-06...Horrible winter, 2nd least snowfall, lowest SDDs, only winter I've seen w/o a 6"+ storm since the late '60s.

07-08...Great winter, snowiest one here, super retention but no big storms - just loads of moderate ones.

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2 minutes ago, ORH_wxman said:

Common denominator of '95-'96, '05-'06, and '07-'08 were all 3 had very good or excellent Decembers. The pattern differed though in how we achieved it....1995 was a big -NAO block and 2007 was literally the opposite...a monster +NAO vortex that actually was displaced far enough southwest that it was acting almost like a block in and of itself and producing a big gradient in the east where it was a massive torch in the mid-atlantic/southeast and pretty cold in New England. 2005 was mostly PAC-driven western ridging, though the NAO wasn't hostile.

A poor December is usually a bad sign in a la nina winter.

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41 minutes ago, 40/70 Benchmark said:

A poor December is usually a bad sign in a la nina winter.

Yes it is....almost no decent Ninas had garbage Decembers. You usually want at least an average December.

I'll be ORH-centric since it's easy for me to remember the years.....but garbage Nina Decembers for ORH are:

2011, 1999, 1998, 1988, 1984, 1973, 1955, 1954

I defined garbage as any December that was in the 30th percentile for snowfall or worse. So in this case for ORH, it would be like 7 inches of snow or worse in December. Of the list of years above, only 1955-1956 was good. All others were pretty horrific including the least snowiest season on record in 1954-1955.

One other year in 1971 was a little bit outside the threshold at 9.6 inches in December. That Nina ended up being a blockbuster. Though just a few days before December started, the huge Thanksgiving 1971 storm hit, so there's another reason to be skeptical of thinking that year was going to bust. All those years I listed above also had garbage Novembers except 1955 (also the one year that didn't have a garbage winter out of that set....wonder if we should combine the two months when looking at Ninas?)

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1 hour ago, 40/70 Benchmark said:

3 Coupling Between Tropical Width and Meridional Variations of MMTG

A fundamental driver of the atmospheric circulation is the meridional temperature gradient. Tropical expansion is associated with a poleward displacement of westerlies, jet streams, and storm tracks (Archer & Caldeira, 2008; Chen et al., 2008; Yin, 2005). These phenomena are all associated with the atmospheric meridional temperature gradients (Kaspi & Flierl, 2007; Lesieur et al., 2000; Sampe et al., 2010; Yang et al., 2019), raising the question of whether the displacement of the meridional temperature gradient is associated with the tropical width.

Given that the tropical width does not vary homogeneously over all ocean basins (Amaya et al., 2018), we examine the tropical width from a regional perspective. The annual‐mean tropical width over an individual ocean basin is calculated as a metric of the latitude where the near‐surface zonal wind changes from easterly to westerly in the subtropics (USF, see section 2). To get the corresponding pattern of SST gradient related to the wider tropics, we regress the USF indices of tropical width onto a field of absolute value of meridional SST gradients over their corresponding ocean basins (Figure 1). Both observations and model results from the CMIP5 exhibit a decrease of SST gradient over the latitude band between 25° and 40°, while an increase of SST gradient is found over the latitude band between 40° and 55°. Such features are notable across all ocean basins. The pattern illustrates that the wider tropics are linked to poleward displacement of the meridional SST gradient over the midlatitude area, that is, MMTG.

 

While the study corroborates John's assertion that the Hadley cell is expanding, it also acknowledges that it should be more prevalent across the southern hemisphere, where there is more ocean.

Interesting.

That is the SST correlation with the wind pattern stuff.. 

https://science2017.globalchange.gov/ 

... corroborates as well, and discusses the atmospheric modal changes that have occurred in the past 30 years as part of this total response in the global hemisphere - Hadley Cell is an atmospheric eddy that girdles the tropics and subtropics around the planet...featuring ( in the means...) rising air near the Equatorial Monsoonal Trough zones and augmented by MJO ... etc..., polarward mass flux from convection deposition in the high troposphere, and downward ambient flow tendencies in the midst of subtropical ridges ... On the polar side of these ridges, the flow terminates to the westerlies band, the demarcates the interface between the Hadley Cell and the Ferrel Cell, which is the polar cell that orients at higher latitudes ( lower if talking about the southern H. ).  The HC expansion is noted in the atmosphere -

 

Refer to chapter 5:    5.2.1 Width of the Tropics and Global Circulation

Not to laboriously reiterate but...the expansion of the HC is butting up against the lower Ferral Cell where cold hypsometric layout and compression resulting, is causing enhancing wind velocities as the balanced geostrophic response.  In fairness, the article/content may not describe this latter wind response outright - and I have been clear this is my own hypothesis, but it is a damn good one!  Regardless of refutation as to cause, the previous "stable" climate R-wave climatology is in peril during colder seasons, because wind speed in the wave mechanics is physically instructive regardless and we have had velocity and gradient saturation ...regardless of  ENSO and other factors - it's become a base-state.  ...

Couple of plausible examples of altered R-wave climate:  NAO blocking rarefied because blocking constructs are inherently more difficult to maintain in excessive X coordinate wind.  Also, tending to fold the top latitude flow over mid latitudes, earlier in Autumn exaggerating early cold loading into Canada, as well as upon exit in springs.

So, if we negate this shit in our seasonal outlooks and/or even modeling -based weekly forecast visions... good luck . 

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1 hour ago, ORH_wxman said:

It did...seems like it's going to be operational now on other sites I guess. But it's still the RGEM at 60-84 hours, lol

Seeing that by weatherbell above just raised an eyebrow with me, It was pretty bad last winter even inside 36 hrs so i don't know how this could be better.

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29 minutes ago, Typhoon Tip said:

This is the SST correlation with the wind pattern stuff.. 

https://science2017.globalchange.gov/ 

... corroborates as well, and discusses the atmospheric modal changes that have occurred in the past 30 years as part of this total response in the global hemisphere - Hadley Cell is an atmospheric eddy that girdles the tropics and subtropics around the planet...featuring ( in the means...) rising air near the Equatorial Monsoonal Trough zones and augmented by MJO ... etc..., polarward mass flux from convection deposition in the high troposphere, and downward ambient flow tendencies in the midst of subtropical ridges ... On the polar side of these ridges, the flow terminates to the westerlies band, the demarcates the interface between the Hadley Cell and the Ferrel Cell, which is the polar cell that orients at higher latitudes ( lower if talking about the southern H. ).  The HC expansion is noted in the atmosphere -

 

Refer to chapter 5:    5.2.1 Width of the Tropics and Global Circulation

Not to laboriously reiterate but...the expansion of the HC is butting up against the lower Ferral Cell where cold hypsometric layout and compression resulting, is causing enhancing wind velocities as the balanced geostrophic response.  In fairness, the article/content may not describe this latter wind response outright - and I have been clear this is my own hypothesis, but it is a damn good one!  Regardless of refutation as to cause, the previous "stable" climate R-wave climatology is in peril during colder seasons, because wind speed in the wave mechanics is physically instructive regardless and we have had velocity and gradient saturation ...regardless of  ENSO and other factors - it's become a base-state.  ...

Couple of plausible examples of altered R-wave climate:  NAO blocking rarefied because blocking constructs are inherently more difficult to maintain in excessive X coordinate wind.  Also, tending to fold the top latitude flow over mid latitudes, earlier in Autumn exaggerating early cold loading into Canada, as well as upon exit in springs.

So, if we negate this shit in our seasonal outlooks and/or even modeling -based weekly forecast visions... good luck . 

It can be deduced from the inferences made in the literature based upon the conducted research with a high degree of confidence. Sure, they didn't state "two", but instead delegated the burden of resolving one plus one to the reader-

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1 hour ago, 40/70 Benchmark said:

A poor December is usually a bad sign in a la nina winter.

we need a good block during a la nina December at least in my area...

most Decembers with an AO -4sd or lower usually had heavy snow that month in the NYC area...

la nina...

12/13/1966 the ao goes below a -4sd...the same time NYC is getting snow and rain but NYC got 7" of snow on 12/24...

12/19/1995 the ao goes below a -4sd...the same time the city is getting an 8" snowstorm...

12/29/2000 the ao goes below a -4sd...NYC got a foot of snow the next day...

12/18/2010 the ao goes below a -5sd...NYC got 20" of snow on 12/26-27...

1950 which is another la nina year had a -4sd ao on the 27th...at the same time NYC was getting 3" of snow and the coldest temp of the winter...9 degrees...not great but it was the best part of that winter...

el nino...

12/20/1963...ao was below -4sd on the 20th...NYC got 7" of snow on the 23rd...

12/27/1968...below -4sd...light snow soon followed...it took till Feb to get a heavy snowstorm...

12/29/1976...below -5sd...light snow that day but the winter had record cold...no heavy snow that year...

12/21/2009...ao was almost -6sd...NYC got 11" of snow on the 19th-20th...

neutral...

12/26/1961...almost -4sd...6" of snow on 12/23-24...

12/31/1962...below -4sd...no heavy snow that winter...Just record cold...13 degree max in NYC 12/31/62...

12/27/1978...below -4sd...it took till Febfuary to get heavy snow...

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8 minutes ago, 40/70 Benchmark said:

It can be deduced from the inferences made in the literature based upon the conducted research with a high degree of confidence. Sure, they didn't state "two", but instead delegated the burden of resolving one plus one to the reader-

Bingo! 

Yeah they're a gov org - they can't make supposition?  Not without huge problems - lol... So, yup ... I don't mind the 'leading prose' ( if you will ) so much, if at least it can be vetted through a modicum of analytics... which this does!  Both apriori but education combined.

Anyway, for the general readers, I love their ( apparently negative rendering when copy and pasting) image acuity and simplicity as reference ... Keeping in mind, I think these base-line states are being disrupted by the expansion and velocity stuff as we are describing... So, perturbing and adulterating these looks ... yup.  how?  million dollar question. I strongly suggest that the straight up ENSO statistical correlations are in trouble... We've had modes on either side of warm(cool) in the last 12 years with apparently limited impacts around global notorious climate zones .. but here is the base... Know what is funny about this... It's odd to me that our best snow winter comes at like +.2 NINO regimes ? when this image smacks as though -1 would be the big nuts... Interesting - 

enso.thumb.jpg.3036ad050a8db8c299a72e714e7cd275.jpg

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8 minutes ago, Typhoon Tip said:

Bingo! 

Yeah they're a gov org - they can't make supposition?  Not without huge problems - lol... So, yup ... I don't mind the 'leading prose' ( if you will ) so much, if at least it can be vetted through a modicum of analytics... which this does!  Both apriori but education combined.

Anyway, for the general readers, I love there image acuity and simplicity as reference ... Keeping in mind, I think these base-line states are being disrupted by the expansion and velocity stuff as we are describing... So, perturbing and adulterating these looks ... yup.  how?  million dollar question. I strongly suggest that the straight up ENSO statistical correlations are in trouble... We've had modes on either side of warm(cool) in the last 12 years with apparently limited impacts around global notorious climate zones .. but here is the base... Know what is funny about this... It's seem odd to me that our best snow winter comes at like +.2 NINO reimes, when this image smacks as though -1 would be the big nuts... Interesting - 

figure5_2.png

My guess at how this unfolds moving forward is deteriorating winter climo for weenies during the heart of winter, but some VERY big dogs on the ends....ie, mother nature forging better Novie/Decembers and March....and even (early) April climo moving forward.

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Just now, 40/70 Benchmark said:

Its been batting .235 since Envt. Canada started making the RGEM piss in a cup at regular time intervals.

We have an interesting model battle on our hands this winter. The NAM and GFS seem to be ever so slowly improving. RGEM is basically a NFL kicker. May make a 62 yd field goal on one try and miss an extra point the next. Euro has been pretty bad in certain situations this summer. 

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Just now, CoastalWx said:

We have an interesting model battle on our hands this winter. The NAM and GFS seem to be ever so slowly improving. RGEM is basically a NFL kicker. May make a 62 yd field goal on one try and miss an extra point the next. Euro has been pretty bad in certain situations this summer. 

From what I understand, ECMWF has made tweaks to augment mid latitude verification at the expense of the tropics. What I do know is that the latter portion of that is confirmed....we will find out about the former over the course of the next several months.

My go-to model concerning the tropics at this point is uncle.

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Just now, 40/70 Benchmark said:

From what I understand, ECMWF has made tweaks to augment mid latitude verification at the expense of the tropics. What I do know is that the latter portion of that is confirmed....we will find out about the former over the course of the next several months.

My go-to model concerning the tropics at this point is uncle.

I haven't heard that, but I'm not sure I get that logic. From a public standpoint and a decision support stand point, I'm not sure why you sacrifice skill on events like tropical cyclone landfalls that can have a huge impact on the population where they make landfall. Yay, congrats on nailing the -RA on Seattle at day 5. 

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Just now, CoastalWx said:

I haven't heard that, but I'm not sure I get that logic. From a public standpoint and a decision support stand point, I'm not sure why you sacrifice skill on events like tropical cyclone landfalls that can have a huge impact on the population where they make landfall. Yay, congrats on nailing the -RA on Seattle at day 5. 

Maybe because Europeans don't care about TCs. :lol:

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4 minutes ago, CoastalWx said:

I haven't heard that, but I'm not sure I get that logic. From a public standpoint and a decision support stand point, I'm not sure why you sacrifice skill on events like tropical cyclone landfalls that can have a huge impact on the population where they make landfall. Yay, congrats on nailing the -RA on Seattle at day 5. 

That is what I heard...nothing to substantiate it. Anecdotally supported by the inferior performance with respect to track this season. Ironically enough, it has been fine with regard to intensity, the lower scoring metric under normal circumstances.

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14 hours ago, michsnowfreak said:

I suppose I could take a blend of all 3 as well, but it's crazy how different my take in Michigan is compared to yours in New York.

95-96... Horrible screw zone. Cold and dry. Great if you like to ice fish

 

05-06...  The definition of front loaded. Lots of snow from Thanksgiving to Christmas.  A mild mess after New Year's.

 

07-08...  Stormy, stormy, stormy with tons of snow.

95-96..started great (Nov/Dec). Jan/Feb were just cold and dry and frankly boring. Mar was great and April too. Overall, we finished above avg (59.2") and 2.4 degrees below avg. 

05-06..started great (Nov/Dec). Rest of the winter was trash. Mild and snowless. If I'm not mistaken, it's top 10 or top 15 least snowiest winter on record at YYZ. Finished the season with 34". 

07-08.. best winter ever. Every month was epic. Finished the season with 92". Another station in the city finished with 99". Double our seasonal avg. 

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12 minutes ago, ORH_wxman said:

Maybe because Europeans don't care about TCs. :lol:

 

7 minutes ago, 40/70 Benchmark said:

That is what I heard...nothing to substantiate it. Anecdotally supported by the inferior performance with respect to track this season. Ironically enough, it has been fine with regard to intensity, the lower scoring metric under normal circumstances.

I mean if the model was meant for Europe...lol. But it is a global model and track means everything. I feel like I did hear something about that too....but I can also tell you it seems to be whiffing on some synoptic stuff here as well. We'll see what happens in the winter. Maybe it gets its swag back. 

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7 minutes ago, Snowstorms said:

95-96..started great (Nov/Dec). Jan/Feb were just cold and dry and frankly boring. Mar was great and April too. Overall, we finished above avg (59.2") and 2.4 degrees below avg. 

05-06..started great (Nov/Dec). Rest of the winter was trash. Mild and snowless. If I'm not mistaken, it's top 10 or top 15 least snowiest winter on record at YYZ. Finished the season with 34". 

07-08.. best winter ever. Every month was epic. Finished the season with 92". Another station in the city finished with 99". Double our seasonal avg. 

I had about 73.5" at my mom's in Wilmington......best I can gather here in Methuen is around 90"....similar to your area.

Sharp gradient. Brian had like a 5' pack.

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3 hours ago, ORH_wxman said:

Common denominator of '95-'96, '05-'06, and '07-'08 were all 3 had very good or excellent Decembers.

 

3 hours ago, tamarack said:

So might I, but for much different opinions:

07-08...Great winter, snowiest one here, super retention but no big storms - just loads of moderate ones.

 

1 hour ago, Snowstorms said:

07-08.. best winter ever. Every month was epic. Finished the season with 92". Another station in the city finished with 99". Double our seasonal avg. 

It was actually funny to hear some of the less than stellar comments even mentioned in the presence of 2007-2008 – I didn’t know it was possible to put those two things together.  Around here it’s typically just spoken of with reverence, or you get comments like you guys have given.  In the past 20 seasons I think most folks would place it only behind 2000-2001.

Will’s strong December theme would certainly fit around here though – nearly 70” that December to help push the season to 200”+ for a very solid winter.

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32 minutes ago, uncle W said:

1970-71 and 2007-08 were terrible here in NYC but they were great well north of here...

1970-71 was another great winter up this way. 71.0" which is 25" above our seasonal average. DJFM all featured below normal temps. 1970-71 La Nina came after two consecutive Nino's (1968-70), similar to this year. 

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