Isotherm Posted October 19, 2016 Share Posted October 19, 2016 8 hours ago, NJwinter23 said: Right just made a quick generalization for the point of the post. That blog goes into grave details, along with situations where the north pac high did not agree with the research. How is your forecast coming along this year Iso? NJ, Yep - agreed. Definitely a fascinating hypothesis which has sufficient evidence to be useful in application (somewhat paradoxical/counter-intuitive as well, given the conventional wisdom regarding stratospheric westerly shear stress/decreased trop blocking). To be honest, I'm not that optimistic [from the standpoint of Eastern cold/snow] right now, though we are still rather early. Conflicting signals regarding NAM/NAO. The stratospheric vortex is significantly weaker than this time last year; however, the question is: will background/exogenous factors permit the maintenance of a weakened vortex through the winter? I am concerned that we'll be combating some unfavorable Atl/Arctic signalling. Most options are still on the table for me, including another very warm winter (though probably not as warm as last winter - virtually impossible). The next 3-4 weeks will deliver important data, so I expect I'll have my winter forecast done by Nov 10 or so. I know last winter we had some good discussions re the stratosphere. I will likely be reassigning weights to various indicators, because some of them are not as reliable as many think (IMO). The SAI has lost some respect in my eyes. Last year, the strat perturbation/-AO anomalous pattern did work out for Jan, but backed off thereafter due to the powerhouse vortex. My guess is that if the Nino were less intense, we probably would have held stronger blocking through Feb with the first SSW attempt working. How about you - what are your thoughts at this point? Are you planning on doing an outlook this year? Link to comment Share on other sites More sharing options...
mattie g Posted October 19, 2016 Share Posted October 19, 2016 Just to keep this thread on track...even if the interest in SAI has severely diminished in the last couple years: October 14: October 15: October 16: October 17: October 18: Quite impressive gains in the last couple days - both north and south of 60N - with the potential for between now and the end of the month. Link to comment Share on other sites More sharing options...
LoveSN+ Posted October 19, 2016 Share Posted October 19, 2016 One thing I certainly have noticed as well, and was first pointed out to me by crankyweatherguy on twitter, is the fact that there is a large snowpack already building up in Canada AND advancing southward. We don't get sustained cold air without Canada having a solid snowpack. Something to keep in mind. Link to comment Share on other sites More sharing options...
billgwx Posted October 19, 2016 Share Posted October 19, 2016 Who's lost interest in SAI? Not this guy. Last winter was so dominated by El Nino I didn't expect -AO to be an overriding factor for the entire winter, instead I figured on some wild swings as one or the other dominated, one of which could bring a big winter storm. This fall we have -AO with NAO to follow suit shortly, also +PNA, advancing snow cover S of 60 N in Siberia, and near record low Arctic ice cover. What's not to like so about potential for a colder and snowier than average winter, especially when flirting with a weak La Nina? Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted October 19, 2016 Share Posted October 19, 2016 21 hours ago, Isotherm said: NJ, Yep - agreed. Definitely a fascinating hypothesis which has sufficient evidence to be useful in application (somewhat paradoxical/counter-intuitive as well, given the conventional wisdom regarding stratospheric westerly shear stress/decreased trop blocking). To be honest, I'm not that optimistic [from the standpoint of Eastern cold/snow] right now, though we are still rather early. Conflicting signals regarding NAM/NAO. The stratospheric vortex is significantly weaker than this time last year; however, the question is: will background/exogenous factors permit the maintenance of a weakened vortex through the winter? I am concerned that we'll be combating some unfavorable Atl/Arctic signalling. Most options are still on the table for me, including another very warm winter (though probably not as warm as last winter - virtually impossible). The next 3-4 weeks will deliver important data, so I expect I'll have my winter forecast done by Nov 10 or so. I know last winter we had some good discussions re the stratosphere. I will likely be reassigning weights to various indicators, because some of them are not as reliable as many think (IMO). The SAI has lost some respect in my eyes. Last year, the strat perturbation/-AO anomalous pattern did work out for Jan, but backed off thereafter due to the powerhouse vortex. My guess is that if the Nino were less intense, we probably would have held stronger blocking through Feb with the first SSW attempt working. How about you - what are your thoughts at this point? Are you planning on doing an outlook this year? Why?? Link to comment Share on other sites More sharing options...
mattie g Posted October 21, 2016 Share Posted October 21, 2016 On 10/19/2016 at 3:11 PM, billgwx said: Who's lost interest in SAI? Not this guy. Last winter was so dominated by El Nino I didn't expect -AO to be an overriding factor for the entire winter, instead I figured on some wild swings as one or the other dominated, one of which could bring a big winter storm. This fall we have -AO with NAO to follow suit shortly, also +PNA, advancing snow cover S of 60 N in Siberia, and near record low Arctic ice cover. What's not to like so about potential for a colder and snowier than average winter, especially when flirting with a weak La Nina? Cohen has taken his lumps in the past few years, so the SAI is no longer the "hot new thing" in terms of indices. This thread is indicative of what I perceive to be a lack of interest. Since the 2011-2012 season, the replies in the "And we begin" threads have been: 11-12: 436 12-13: 222 13-14: 125 14-15: 556 15-16: 208 16-17: 35 (through October 21) I'm not trying to say that no one is interested, but rather that the interest is way down from years past, and I think that's a lot to do with "failures" of the SAI and people poking holes in the theory. Personally, I have no meteorological chops, so I find the SAI interesting because it's easy for me to follow and understand! Link to comment Share on other sites More sharing options...
nrgjeff Posted October 21, 2016 Share Posted October 21, 2016 SAI is not very successful on its own. However when one looks at pressure anomalies over Siberia vs closer to the mid-latitudes some value over climo is achieved. Best to wait until November for the first stab there. Link to comment Share on other sites More sharing options...
Weltanschauung Posted October 21, 2016 Share Posted October 21, 2016 monitoring SAI Link to comment Share on other sites More sharing options...
LoveSN+ Posted October 21, 2016 Share Posted October 21, 2016 Looking about as good as you can hope for from this indicator. This really should be a great season to evaluate if they SAI really only works well in neutral-ish ENSO conditions. Not only that, but if Cohen's forecast is right due to blocking or different factors. Link to comment Share on other sites More sharing options...
LoveSN+ Posted October 22, 2016 Share Posted October 22, 2016 GFS says snowfall south of 60N will be quite heavy up to November 1st. Interesting times lay ahead this winter. Link to comment Share on other sites More sharing options...
DTWXRISK Posted October 22, 2016 Share Posted October 22, 2016 On 10/19/2016 at 3:11 PM, billgwx said: Who's lost interest in SAI? Not this guy. Last winter was so dominated by El Nino I didn't expect -AO to be an overriding factor for the entire winter, instead I figured on some wild swings as one or the other dominated, one of which could bring a big winter storm. This fall we have -AO with NAO to follow suit shortly, also +PNA, advancing snow cover S of 60 N in Siberia, and near record low Arctic ice cover. What's not to like so about potential for a colder and snowier than average winter, especially when flirting with a weak La Nina? +2 Link to comment Share on other sites More sharing options...
DTWXRISK Posted October 22, 2016 Share Posted October 22, 2016 ALL WEAK LA NINA AUTUMN WINTERS Link to comment Share on other sites More sharing options...
DTWXRISK Posted October 22, 2016 Share Posted October 22, 2016 WEAK LA NINA WINTERS in the that featured Mod /strong El Nino Previous Winter that died off in the Spring this scenario is more likely ASSUMING the weak La Nina 1) stays weak 2) last all winter long Link to comment Share on other sites More sharing options...
DTWXRISK Posted October 22, 2016 Share Posted October 22, 2016 WEAK LA NINA in the AUTUMN that died off by the time early/ mid DEC ( I like this scenario best) woof Link to comment Share on other sites More sharing options...
DTWXRISK Posted October 22, 2016 Share Posted October 22, 2016 On 10/21/2016 at 3:55 PM, Weltanschauung said: monitoring SAI LINK FOR THIS ? Link to comment Share on other sites More sharing options...
Treckasec Posted October 22, 2016 Share Posted October 22, 2016 18z GFS animation for snow cover starting from now to November 1st. Seems like we'll end October with a high amount of snow cover. Link to comment Share on other sites More sharing options...
Treckasec Posted October 22, 2016 Share Posted October 22, 2016 Link to comment Share on other sites More sharing options...
LoveSN+ Posted October 23, 2016 Share Posted October 23, 2016 Could we have the largest SAI ever this October? It certainly looks possible. Link to comment Share on other sites More sharing options...
DTWXRISK Posted October 24, 2016 Share Posted October 24, 2016 WOW hell of a way to end OCT and pile up the SIBERIAN snow cover ( amounts and area) Link to comment Share on other sites More sharing options...
InstantWeatherMaps Posted October 26, 2016 Share Posted October 26, 2016 On 10/22/2016 at 6:13 PM, Treckasec said: 18z GFS animation for snow cover starting from now to November 1st. Seems like we'll end October with a high amount of snow cover. Nice GIF. What did you use to make it? Link to comment Share on other sites More sharing options...
Treckasec Posted October 29, 2016 Share Posted October 29, 2016 On 10/25/2016 at 8:35 PM, InstantWeatherMaps said: Nice GIF. What did you use to make it? I think I used Giphy. Link to comment Share on other sites More sharing options...
Treckasec Posted October 31, 2016 Share Posted October 31, 2016 Wow! Link to comment Share on other sites More sharing options...
CAD_Wedge_NC Posted October 31, 2016 Share Posted October 31, 2016 This up-coming cold season should be a true test of the correlation between SAI and NAO. If we aren't dominated by Atlantic blocking this winter, then I see no reason to call this index a useful tool for any future long-range winter forecasts. Link to comment Share on other sites More sharing options...
LoveSN+ Posted October 31, 2016 Share Posted October 31, 2016 9 hours ago, CAD_Wedge_NC said: This up-coming cold season should be a true test of the correlation between SAI and NAO. If we aren't dominated by Atlantic blocking this winter, then I see no reason to call this index a useful tool for any future long-range winter forecasts. I certainly agree. If there happens to be no -AO and/or no strong SSW that disrupts the polar vortex, then Cohen's theory definitely is misguided. Link to comment Share on other sites More sharing options...
OHweather Posted October 31, 2016 Share Posted October 31, 2016 10 hours ago, CAD_Wedge_NC said: This up-coming cold season should be a true test of the correlation between SAI and NAO. If we aren't dominated by Atlantic blocking this winter, then I see no reason to call this index a useful tool for any future long-range winter forecasts. SAI correlates with the AO, not the NAO FWIW Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted November 1, 2016 Share Posted November 1, 2016 3 hours ago, OHweather said: SAI correlates with the AO, not the NAO FWIW I would be suprised to see a postive NAO in the face of a strongly negative AO...there is about a .6 correlation...as you know. Link to comment Share on other sites More sharing options...
OHweather Posted November 1, 2016 Share Posted November 1, 2016 1 hour ago, 40/70 Benchmark said: I would be suprised to see a postive NAO in the face of a strongly negative AO...there is about a .6 correlation...as you know. Definitely agree, but I do think it's fair to point out that Cohen is trying to predict the AO and not the NAO. It can be very blocky in general and not perfect over the Atlantic...probably not a very warm patter but it could happen. Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted November 1, 2016 Share Posted November 1, 2016 3 hours ago, OHweather said: Definitely agree, but I do think it's fair to point out that Cohen is trying to predict the AO and not the NAO. It can be very blocky in general and not perfect over the Atlantic...probably not a very warm patter but it could happen. Yes, absolutely. Link to comment Share on other sites More sharing options...
Badfishranch Posted November 1, 2016 Share Posted November 1, 2016 Can somebody post that line graph of the snow build like above? TYIA Link to comment Share on other sites More sharing options...
billgwx Posted November 1, 2016 Share Posted November 1, 2016 The numbers for Snow Cover Extent at the end of October are in at the Rutgers Global Snow Lab...finished 3rd behind 1976 and 2014, and is in a virtual tie with 2002. All of those following winters were severe in the East in one way other another: 1976-77 cold and huge lake effect snow, 2002-03 cold and constant snow including PD2, 2014-15 Long Island/New England and NYC "near hit" blizzard and Boston annual record snowfall. WOW. Now we factor in ENSO, QBO, etc. for further clues... Link to comment Share on other sites More sharing options...
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