Jump to content
  • Member Statistics

    17,586
    Total Members
    7,904
    Most Online
    23Yankee
    Newest Member
    23Yankee
    Joined

Winter 2014-2015 Thread


Ji

Recommended Posts

  • Replies 2.1k
  • Created
  • Last Reply

I just saw this on my Twitter feed. How will the above normal Siberian snow cover be impacted? https://pbs.twimg.com/media/B1hWjJUCcAAfxL3.png

 

Potentially, this is the RESULT of the snowcover.  This is the mechanism that Cohen and Co. have postulated, that above normal snowcover leads to wave activity that propagates into the stratosphere and disrupts the vortex, leading to a -AO.  And lo and behold, it looks like we're going to have a solidly -AO for much of the first 2 weeks of November at least.  This warming indicated on the Euro would suggest it continues.  

Link to comment
Share on other sites

Potentially, this is the RESULT of the snowcover.  This is the mechanism that Cohen and Co. have postulated, that above normal snowcover leads to wave activity that propagates into the stratosphere and disrupts the vortex, leading to a -AO.  And lo and behold, it looks like we're going to have a solidly -AO for much of the first 2 weeks of November at least.  This warming indicated on the Euro would suggest it continues.  

not so sure it could get any better from our perspective either considering it's close to the top of the scale

Link to comment
Share on other sites

not so sure it could get any better from our perspective either considering it's close to the top of the scale

For some reason I thought I was sharing a 500mb chart. That wouldn't be so pretty; Glad to see the signs heading in our favor.

Link to comment
Share on other sites

Agreed. Nov snow isn't something to wager anything on around here. 95-96 & 96-97 we're the last 2 measurable at IAD. But not too far back in the 70's and 80's there were enough occurrences to keep the disco open to a chance.

March last year was an obvious statistical anomaly but it wasn't just one fluke. It was a solid snow pattern for a few weeks. Ensembles are advertising a pattern after next weekend that could produce snow in Nov. Obviously if any threat appears the further n-w the better chance.

 

Tryting to decide whther to hold off on my two week outlooks until after vets day or to write one in the next week or so.  Pattern does look cold and I'm increasingly optimistic about below normal temps for the winter. 

Link to comment
Share on other sites

Potentially, this is the RESULT of the snowcover.  This is the mechanism that Cohen and Co. have postulated, that above normal snowcover leads to wave activity that propagates into the stratosphere and disrupts the vortex, leading to a -AO.  And lo and behold, it looks like we're going to have a solidly -AO for much of the first 2 weeks of November at least.  This warming indicated on the Euro would suggest it continues.  

Good answer....thanks for posting.

 

It also is worth noting that that is a 360 hour forecast which is unlikely to be correct, Euro ensembles or not.

Link to comment
Share on other sites

Tryting to decide whther to hold off on my two week outlooks until after vets day or to write one in the next week or so.  Pattern does look cold and I'm increasingly optimistic about below normal temps for the winter. 

OMG, you just sent a bunch of people over the edge.

Link to comment
Share on other sites

Tryting to decide whther to hold off on my two week outlooks until after vets day or to write one in the next week or so.  Pattern does look cold and I'm increasingly optimistic about below normal temps for the winter. 

 

The d10-15 h5 mean is really something to behold. Quite similar with anomaly placements to Nov 02 in our hemisphere. 02 and 76 are popping up a lot in CPC d8 & 11+

 

Here's what  the second half of Nov looked like in 02

 

post-2035-0-26047400-1415029123_thumb.gi

 

Last 2-3 euro ens runs look like this with 5 day mean:

 

post-2035-0-24025000-1415029154_thumb.gi

 

 

Another interesting comparison is the Oct AO behavior compared to Oct this year:

 

post-2035-0-59915800-1415029186_thumb.gi

 

 

post-2035-0-01131900-1415029314_thumb.gi

 

 

02-03 was one of the few -ao winters that had consistent blocking starting at the beginning of Nov and lasting almost a full 3 months until late Jan. 

 

post-2035-0-18310200-1415029536_thumb.jp

 

 

76-77 and 09-10 didn't really latch on to a lasting -ao pattern until Dec. 

 

It will be interesting as we move forward if the current -AO forecast to strong neg is the beginning of a lasting pattern into the winter months or will there be a relaxation in Dec before re-establishing. 

 

Most strong -ao's in winter last at least 45-60 days but I'm not sure about typical periods when they begin in Nov. I'll dig around a little. 

Link to comment
Share on other sites

Good answer....thanks for posting.

 

It also is worth noting that that is a 360 hour forecast which is unlikely to be correct, Euro ensembles or not.

It is a 360hr forecast, but 2 facts make far more than a 360hr GFS forecast:

1.  It's the Euro ensembles

2.  The stratosphere is far more predictable at long leads than the troposphere.  

Link to comment
Share on other sites

It is a 360hr forecast, but 2 facts make far more than a 360hr GFS forecast:

1.  It's the Euro ensembles

2.  The stratosphere is far more predictable at long leads than the troposphere.  

 

It's a strong signal and begins well in advance of d15. Another thing that gives it some cred is it's the expected result of a high SAI October. 06 was an obvious disaster irt the AO response but it was also the opposite of that 50mb plot in Nov. ORH and Coastal have made some really nice posts about it in the SNE forum. 

Link to comment
Share on other sites

Issue is weak ninos aren't big snow producers here...so we may be looking at Mattie's worst nightmare...cold and dry

Given that weak ninas/cold neutrals and mod ninos are typically the best for us, it's curious that weak ninos/warm neutrals haven't been big snow producers.  I wonder if this is all just small sample size issues and with a suitably large sample (and a climate that isn't shifting), we'd see a more normal distribution around some "ideal ENSO" state.  

 

It makes meteorological sense (to me at least) why mod ninos are our biggest years and why strong ninos and strong ninas are typically worse.  I'd think that that warm neutrals/weak ninos SHOULD be better than they have been, on average.  

Link to comment
Share on other sites

Given that weak ninas/cold neutrals and mod ninos are typically the best for us, it's curious that weak ninos/warm neutrals haven't been big snow producers.  I wonder if this is all just small sample size issues and with a suitably large sample (and a climate that isn't shifting), we'd see a more normal distribution around some "ideal ENSO" state.  

 

It makes meteorological sense (to me at least) why mod ninos are our biggest years and why strong ninos and strong ninas are typically worse.  I'd think that that warm neutrals/weak ninos SHOULD be better than they have been, on average.

Seems like we are hitting the indices jackpot this year as modeled...wonder if that ever has happened with a week niño and how that changes things if at all. NAO gonna be most crucial in my opinion this year...gotta get any storm to turn the corner...or there will be a lot of congrats South Carolina

Link to comment
Share on other sites

Nino is trying hard but a seriously late bloomer. I still think getting an official nino is only for posterity at this point but would still be an accomplishment nonetheless after constantly chasing a ghost this year. 

 

anomnight.11.3.2014.gif

another tick warmer this week where it counts

                Nino1+2      Nino3        Nino34        Nino4 Week          SST SSTA     SST SSTA     SST SSTA     SST SSTA
 15OCT2014     21.5 0.7     25.5 0.5     27.2 0.5     29.4 0.7 22OCT2014     21.8 0.8     25.8 0.8     27.2 0.5     29.4 0.7 29OCT2014     21.8 0.6     25.8 0.9     27.3 0.6     29.4 0.8
Link to comment
Share on other sites

It's a strong signal and begins well in advance of d15. Another thing that gives it some cred is it's the expected result of a high SAI October. 06 was an obvious disaster irt the AO response but it was also the opposite of that 50mb plot in Nov. ORH and Coastal have made some really nice posts about it in the SNE forum. 

 

 Bob,

 I guess you don't realize that the 2006 SAI was actually positive despite the rather generous SCE. So, the SAI, itself a better predictor than the SCE for the DJF AO, actually made an excellent DJF 06-07 AO prediction.

 

 SAI:   http://onlinelibrary.wiley.com/doi/10.1029/2011GL049626/full

 

 I used to get confused about what is a better predictor for the AO, but I think I have it straight now.

 

Edit: correction. I should have said that the 2006 SAI was actually negative, not positive, as it is negatively correlated with the AO. Otherwise, the rest of the post is what I meant to say.

Link to comment
Share on other sites

Nino is trying hard but a seriously late bloomer. I still think getting an official nino is only for posterity at this point but would still be an accomplishment nonetheless after constantly chasing a ghost this year. 

 

anomnight.11.3.2014.gif

Have there been any late season Nino analog years? For anyone interested, NASA has a nice historical database for sst and surface temperature charts. http://data.giss.nasa.gov/gistemp/maps/

Link to comment
Share on other sites

I'm not from the mid atlantic but I read the posts here a lot. The best fit year as an analog I found based solely on Niño was 1976-77. It started in the ASO tri-monthly. 1977-78 was pretty close to it as well.

Thanks!

Link to comment
Share on other sites

I'm not from the mid atlantic but I read the posts here a lot. The best fit year as an analog I found based solely on Niño was 1976-77. It started in the ASO tri-monthly. 1977-78 was pretty close to it as well.

 

Is there such a thing as a "quick-look analogs" page anywhere online?  It would be a year-by-year database of atmospheric conditions (Nino/Nina, ENSO, AO, NAO, etc), and US regional monthly temp and precip variation.  So that when someone lists a less familiar year, you can go right to the page and say "ah, I see why that's being said and where it could lead"...

Link to comment
Share on other sites

I'm not from the mid atlantic but I read the posts here a lot. The best fit year as an analog I found based solely on Niño was 1976-77. It started in the ASO tri-monthly. 1977-78 was pretty close to it as well.

Fwiw, I think a big difference those years was in the Gulf of Alaska.

Link to comment
Share on other sites

 Bob,

 I guess you don't realize that the 2006 SAI was actually positive despite the rather generous SCE. So, the SAI, itself a better predictor than the SCE for the DJF AO, actually made an excellent DJF 06-07 AO prediction.

 

 SAI:   http://onlinelibrary.wiley.com/doi/10.1029/2011GL049626/full

 

 I used to get confused about what is a better predictor for the AO, but I think I have it straight now.

 

Edit: correction. I should have said that the 2006 SAI was actually negative, not positive, as it is negatively correlated with the AO. Otherwise, the rest of the post is what I meant to say.

 

I thought it was a bust year for some reason. It was a big gainer for all of eurasia based on Rutgers but I didn't dig deeper into the below 60N stuff. 

 

post-2035-0-75910300-1415042754_thumb.gi

Link to comment
Share on other sites

Is there such a thing as a "quick-look analogs" page anywhere online? It would be a year-by-year database of atmospheric conditions (Nino/Nina, ENSO, AO, NAO, etc), and US regional monthly temp and precip variation. So that when someone lists a less familiar year, you can go right to the page and say "ah, I see why that's being said and where it could lead"...

That's why I included the 'based solely on Niño' phrase. I'm pretty sure that is the year I have seen used the most as an analog to date. I don't know of a database like that but it would be awesome.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...