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CAPE

Winter 2020-21 Discussion

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On 9/23/2020 at 2:20 PM, 40/70 Benchmark said:

List me all of the la Nina winters that the mid atl did well with a +NAO...

We did pretty well in 2000 by our standards but all the snow fell in 2 weeks when there was blocking. The rest of the winter sucked.  We can always root for a fluke like that. Actually, A few years ago heading into the 2017 nino I went back and examined the h5 look leading up to every Nina warning even at BWI going back to 1950.  Every single one had some kind of high latitude help. In some cases it was bootleg and didn’t show up well on the numerical NAO. Like blocking near Hudson Bay which is actually one of our better ways to back into a snow event in a flawed longwave pattern here.  But I couldn’t find a single significant Nina snow without at least a decent look up top to aid. If the NAO looks like hot garbage in a Nina we can try to luck into some kind of scraps like a front end inch or two or a clipper but we’re not getting anything of substance. 

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1 hour ago, psuhoffman said:

We did pretty well in 2000 by our standards but all the snow fell in 2 weeks when there was blocking. The rest of the winter sucked.  We can always root for a fluke like that. Actually, A few years ago heading into the 2017 nino I went back and examined the h5 look leading up to every Nina warning even at BWI going back to 1950.  Every single one had some kind of high latitude help. In some cases it was bootleg and didn’t show up well on the numerical NAO. Like blocking near Hudson Bay which is actually one of our better ways to back into a snow event in a flawed longwave pattern here.  But I couldn’t find a single significant Nina snow without at least a decent look up top to aid. If the NAO looks like hot garbage in a Nina we can try to luck into some kind of scraps like a front end inch or two or a clipper but we’re not getting anything of substance. 

Gotta be careful with that "we" thing!

Again, the 2 most recent Ninas both produced big snow events in early Jan(of '17 and '18) for eastern areas, with a pretty crappy look up top. Just saying, it can happen.

In general, yes, we need a decent HL look(AO/NAO) for significant snow down here in a Nina, but the same can be said in most cases even in a Nino, and especially for the lowlands. 

 

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The h5 look leading up to the coastal blizzard of Jan 2018, aka bomb cyclone. Driven by a very favorable Pacific during that period. Defo a +NAO.

Composite Plot

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 If you live in the MA outside of the microclimate areas in the western highlands, lower the bar for "good" winter when we are in a Nina. Median snowfall should be the "goal". After last winter, a 10" total for DC/BWI would seem epic. Ofc there is always luck.

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22 minutes ago, CAPE said:

 If you live in the MA outside of the microclimate areas in the western highlands, lower the bar for "good" winter when we are in a Nina. Median snowfall should be the "goal". After last winter, a 10" total for DC/BWI would seem epic. Ofc there is always luck.

I believe in the WD index that I believe @Bob Chill made up

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Regarding the forecasted mild, fluke cold Winter of 2010-11, this area in the far Southwestern part of the Forum wound up with an above average Snow Season. Dec. and January was well above , Feb. Avg. Temps were well below. 

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2 hours ago, CAPE said:

Gotta be careful with that "we" thing!

Again, the 2 most recent Ninas both produced big snow events in early Jan(of '17 and '18) for eastern areas, with a pretty crappy look up top. Just saying, it can happen.

In general, yes, we need a decent HL look(AO/NAO) for significant snow down here in a Nina, but the same can be said in most cases even in a Nino, and especially for the lowlands. 

 

I just figure when most people outside our region want a quick snapshot they are focused on the urban corridor from DC-Baltimore. You and I are not really in the mainstream here. 2000 wasn’t that good up here (but I would take it) since it’s a lot harder to fluke to avg with a couple storms up here. But the “we” was for the main cohort in this forum. You can get clipped by late developing miller bs and coastal scrapers much easier and in a Nina that advantaged your area over DC sometimes.  

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2 hours ago, Daniel Boone said:

Regarding the forecasted mild, fluke cold Winter of 2010-11, this area in the far Southwestern part of the Forum wound up with an above average Snow Season. Dec. and January was well above , Feb. Avg. Temps were well below. 

Only pulled a 19.5 here, and 12.6 of that fell in December. Then we nickel and dimed our way to the finish line.

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7 hours ago, psuhoffman said:

I just figure when most people outside our region want a quick snapshot they are focused on the urban corridor from DC-Baltimore. You and I are not really in the mainstream here. 2000 wasn’t that good up here (but I would take it) since it’s a lot harder to fluke to avg with a couple storms up here. But the “we” was for the main cohort in this forum. You can get clipped by late developing miller bs and coastal scrapers much easier and in a Nina that advantaged your area over DC sometimes.  

I get that. Just playing devil's advocate a bit. We always want HL blocking, regardless of ENSO state. It greatly increases the odds of significant snow events for this area. A favorable EPO is probably second after a -AO/NAO, as we get big cold air delivery and even without much help in the NA, we can snow.

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2 hours ago, CAPE said:

Once we get into winter with Nina atmospheric response, all those pretty colors will be transposed.

I strongly doubt it man. They will just end up stuck in Greenland with a raging positive NAO. Nothing kills winter faster than cold Octobers.

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7 minutes ago, Vice-Regent said:

I strongly doubt it man. They will just end up stuck in Greenland with a raging positive NAO. Nothing kills winter faster than cold Octobers.

That's what I said- Transposed.. switched...inverted.. wrong phase.

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1 hour ago, Vice-Regent said:

I strongly doubt it man. They will just end up stuck in Greenland with a raging positive NAO. Nothing kills winter faster than cold Octobers.

Haven't we not had a colder than average October in around a decade, with the last one being October 2009? Not trying to throw out outliers like that, but it's hard to assume something like that when the sample size in recent memory is rather limited. 

But yes I agree with the sentiment surrounding what the colors will look like come December. 

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2 hours ago, CAPE said:

That's what I said- Transposed.. switched...inverted.. wrong phase.

There is a quote from prince’s bride that works here 

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6 hours ago, CAPE said:

I get that. Just playing devil's advocate a bit. We always want HL blocking, regardless of ENSO state. It greatly increases the odds of significant snow events for this area. A favorable EPO is probably second after a -AO/NAO, as we get big cold air delivery and even without much help in the NA, we can snow.

Agree with all this. But what I found (and most know) is in a Nina it’s even harder to luck our way to a significant snow without any HL blocking.  A lot of that is due to a less potent stj. Without blocking in any regime our best shot is to luck into a juiced up but progressive wave. Those are really unlikely without any stj help. But that is especially pertinent to DC. They are too far west to benefit from waves that develop late as they infuse Atlantic moisture. DC needs the gulf as it’s main moisture source. Only exception is a slow moving amplified bomb. But we need blocking for that so again catch 22!  So it’s REALLY difficult for DC to get a significant snow in a +NAO Nina regime. Even more so than in other enso states. 

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Simon just added this to his cool reference site. 

 

 

 

GEFS: 35-day 10 hPa 60°N 

The new GEFSv12 now features a 35-day run every day at 00Z. Shown here is the output from the previous day’s run, due to the time taken for the data to appear on NOMADS.

Note that, because of the length of the forecast, systematic model biases are more likely to impact the output. These are not accounted for here.

Ensemble plume

 

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4 hours ago, Cobalt said:

Haven't we not had a colder than average October in around a decade, with the last one being October 2009? Not trying to throw out outliers like that, but it's hard to assume something like that when the sample size in recent memory is rather limited. 

But yes I agree with the sentiment surrounding what the colors will look like come December. 

Our last October trace on snow was 2011-2012.  Cold Octobers are bad for our winter.

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31 minutes ago, BTRWx's Thanks Giving said:

Our last October trace on snow was 2011-2012.  Cold Octobers are bad for our winter.

At least we know we can't do worse than that winter...lol (because we just had the same total last winter!l

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53 minutes ago, BTRWx's Thanks Giving said:

Our last October trace on snow was 2011-2012.  Cold Octobers are bad for our winter.

October snow is way too small a sample size to draw firm conclusions 

Thats like if some minor league player got called up for one game and hit 1/3 thinking they will bat .333 for their career! 

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28 minutes ago, WxUSAF said:

@griteater with a great thread that seems fairly encouraging to me

https://twitter.com/griteater/status/1309524598480949250?s=21

And the  latest CFS runs look like this for November. Matches his composite for November preceding those winters pretty well. Who knows if it has a clue- but it has been pretty persistent in hinting at HL +heights for Fall lately.

cfs-mon_01_z500a_namer_2.png

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29 minutes ago, WxUSAF said:

@griteater with a great thread that seems fairly encouraging to me

https://twitter.com/griteater/status/1309524598480949250?s=21

I agree there is still hope this year ends up in the  “better” Nina category.  When I examined past Nina archetypes I found it very difficult to determine reliable predictive characteristics we could use ahead of time. The one would be extremely cold north Pac SST (Which almost always was a kiss of death) but we don’t have that.  Unfortunately some still ended up crap anyways. But there is hope!  However...notice most of even the “better” colder Nina Years were still more frustrating than not. 1996 aside the rest still ended up below avg in DC. But they did get closer to median and at least had chances in the area and legit threats to track and some places in our region did better in some of those years. So they are “better”. But it’s wise to set the bar pretty low in a Nina. Even a “good” Nina is simply getting anywhere close to avg.  A median snowfall winter is a huge win in any Nina imo. If we get super lucky and 1996 decides to repeat itself great. But I’ll save my sanity not counting on that. 

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13 minutes ago, CAPE said:

And the  latest CFS runs look like this for November. Matches his composite for November preceding those winters pretty well. Who knows if it has a clue- but it has been pretty persistent in hinting at HL +heights for Fall lately.

cfs-mon_01_z500a_namer_2.png

Where’s our “persistence” crew???  I’m not saying I buy that. I don’t. But...I find it funny that our resident persistence worshipers that like to tell us the crap pattern will continue because....persistence...are suddenly saying “but it won’t last” when the pattern is good. 

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1 minute ago, psuhoffman said:

I agree there is still hope this year ends up in the  “better” Nina category.  When I examined past Nina archetypes I found it very difficult to determine reliable predictive characteristics we could use ahead of time. The one would be extremely cold north Pac SST (Which almost always was a kiss of death) but we don’t have that.  Unfortunately some still ended up crap anyways. But there is hope!  However...notice most of even the “better” colder Nina Years were still more frustrating than not. 1996 aside the rest still ended up below avg in DC. But they did get closer to median and at least had chances in the area and legit threats to track and some places in our region did better in some of those years. So they are “better”. But it’s wise to set the bar pretty low in a Nina. Even a “good” Nina is simply getting anywhere close to avg.  A median snowfall winter is a huge win in any Nina imo. If we get super lucky and 1996 decides to repeat itself great. But I’ll save my sanity not counting on that. 

Aside from abundant blocking, was there any reason that it seems like that's been the only Nina in recent memory that produced those sorts of results? Seems like that winter also had some some characteristics that were unlike a Nina too so I guess that could be why just about any blocking we've had in recent Ninas has fallen short.

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Just now, psuhoffman said:

Where’s our “persistence” crew???  I’m not saying I buy that. I don’t. But...I find it funny that our resident persistence worshipers that like to tell us the crap pattern will continue because....persistence...are suddenly saying “but it won’t last” when the pattern is good. 

Yeah, well proceed with caution lol. We have seen plenty of advertised good looks up top in the LR in recent winters and outside of something transient/bootleg, it never materializes. But given we are just about to October, and we are seeing some 'decent' signs, there is time for a bit of optimism before all hopes and dreams get crushed. And ofc there is the WDI. Oh and solar min. And smoke/ash!

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