FWIW..

(a little speculation here..)

El Nino's ending (cooling E Pac), and (soon-to-be) ENSO-neutral this Summer.

I can hear the naysayers already ("yes, but.. some La Nina years have surprising amounts of snow"), with the more common scenario for SoCal being the tendency to be drier, rather than wetter. Yeah, I know, post up those defiant anomalies to the typical La Nina pattern (MMSA's biggest snowfall year wasn't even an El Nino; not sure about 1969 tho)..

Unfortunately, after the ENSO-transition from neutral into the 'La Nina' condition, Mammoth may see less snow than in 2009-2010. No surprise, right?

Nothing's guaranteed of course, but the heavier snowfall and rainfall may be returning back up to the PNW next Winter..

NOAA's view

(ok, have at it. At least its raining today!))

It all depends on how strong any La Nina would end up being and its too early to tell. Some charts from the weekly update.



Quite a cold pool for the central PAC projected going into next winter.

Thats why I bought the pass insurance. Guarantees 475 inches. $1 back for every inch it falls short.

Without access to the all-important data and modeling-software NOAA has, we can't predict the actual STRENGTH of the La Nina (at this time), only the likelihood of it returning. I wasn't saying as to the condition being strong, moderate, or weak, only pointing out the past tendency for the overall pattern to effect precipitation and temperature numbers (as contrasted vs an El Nino).

Guess we'll have to wait and see what the ocean temperatures are, and also the trade wind patterns that take place in a few months..

Speculate away on whether its a strong, weak, or moderate La Nina..

The reason I brought up the strength is that I believe in TonyC's observation that the strength plays an important role in how much the central Sierra and SoCal are affected.

I can certainly believe a La Nina condition would return on the rebound from a moderate to strong El Nino that we just had.

Yeah, I too started thinking about Tony's description on how the strength of an El Nino or a La Nina effect snowfall at various ski hills. Weak patterns are quite different than strong ones as to any geographical snowfall distribution!

So when we do see the evidence of that (definite) strong or weak anomaly-data (temps/winds), we'll then have a much better idea (or likelihood) of where the heaviest snow will probably be falling in the country this Winter..

It will snow at Mammoth, but how MUCH?

You guys might find this post on the possibility of a La Nina interesting. Basically the author is saying this El Nino is a little different, calling it a El Nino Modoki and claiming that La Ninas rarely follow this type of El Nino. Only time will tell!

http://wattsupwiththat.com/2010/05/01/h ... this-year/

I think El Nino and La Nina should get together and party...
then everyone will be happy..

The infamous year of 1969 was an El Nino year.

The Dweeber

That article got too complicated for me. I do something much simpler and cruder. I try to find an analogous event on the historical chart for ONI:

http://www.cpc.ncep.noaa.gov/products/a ... ears.shtml

for strength and duration. So far on a very quick skim it does look like 1957-1958 is closest (although our data isnt all in yet) and that was just followed by neutral conditions. But that event was also preceded by a La Nina it seems.

We are looking at 58 as a possible analog for summer weather conditions for reasons Cheaps cited above.

And how was the summer of '58? I wasn't here to experience it first hand

When I try to analyze El Nino/La Nina I use this info: http://www.esrl.noaa.gov/psd/people/kla ... table.html.
It was recommended to me by Seattle meteorologist (and powder junkie) Larry Schick.

With regard to impact upon snowfall there are 2 ways I've tried to look at it. First is correlating the monthly MEI index to monthly snowfall. The results are in 3 articles I wrote in the fall of 2007, headed into a strong La Nina season:
http://webpages.charter.net/tcrocker818/El_Nino.htm
http://webpages.charter.net/tcrocker818/La_Nina.htm
http://webpages.charter.net/tcrocker818 ... _areas.htm

The methodology of those articles has the advantage of utilizing as much data as possible but does not address the issue that the El Nino/La Nina might need to be of at least moderate strength to have any effect at all. So I've recently looked at the months through 2008-09 where MEI is > 0.750 for El Nino and < -0.750 for La Nina. For Mammoth there are 42 El Nino months which average 113% of normal snowfall and 31 La Nina months which average 90% of normal snowfall. For Southern California there are 37 El Nino months which average 125% of normal snowfall and 20 La Nina months which average 82% of normal snowfall.

There is a legitimate question if this is enough data to draw firm conclusions. I'm guessing that many of you would be surprised that for Kirkwood there are 37 El Nino months which average 103% of normal snowfall and 22 La Nina months which average 107% of normal snowfall. Actually, the Tahoe areas don't correlate well in my articles because they have just as many good La Nina seasons as bad ones. However, most of the Tahoe areas have higher percentages than Kirkwood for the El Nino months.

The problem with the "look at El Nino/La Nina seasons" method is that there have been only 4 La Nina seasons since 1977, and not many areas have snow data before then. For those places there are only 16 La Nina months (I'm just looking at December-March for the most credible snow data), and it doesn't take much in the way of unusual weather to move those stats. The classic example is southern and western Colorado, which by popular opinion is considered favored by El Nino. Several of those places (Aspen, Crested Butte, Telluride) set their all time snowfall records in the strong La Nina year of 2007-08. Since that's 1/4 of the La Nina data naturally those areas now favor La Nina by the "look at El Nino/La Nina seasons" method. By the correlation method those areas, like Tahoe, are close to neutral, and I believe that's the best assumption to make for them.

The question of "what kind of season follows an El Nino" is subject to the same question of sufficient data. The records go back to the 1950's instead of the late 1970's, but now we've subdividing the data between "normal El Ninos" and "Modoki El Ninos." Another hypothesis would be that the stronger the El Nino, the more likely a swing to a strong La Nina. That works well for 1972-73 and 1997-98 but not for 1982-83 or 1991-92. FYI 2009-10 was a fairly strong El Nino, 7th highest of the 60 years of MEI data and just short of 1972-73.

Bottom line is all we want to know is this... when is the next powder day!