Tahoe Daily Snow

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By Bryan Allegretto, Forecaster Posted 5 years ago October 20, 2018

Falling Off the Fence...

Update

It looks like sunny and dry weather with highs in the 60's could continue for a while.  

The trend on the forecast models has been to push the storm track slightly North through the next week.  That means we are no longer on the fence, with less of a chance to see any precip, maybe just wind and some clouds.

There are still some runs of the GFS and European model that have a final storm grazing us on Monday the 29th before the ridge builds in near the coast.  Here is the 10-day precip forecast.

precip

Some of the GFS runs and the ensemble mean runs have the ridge building in by next weekend.  Then there is good model consensus that it lasts into the first few days of November.  So we should have a prolonged dry period ahead for a couple weeks unless something changes.

ridge

There is also some agreement that during the first week of November the ridge shifts back a little to the west.  That could allow for some colder air to be pushed into the West, and maybe back to a slider pattern as we saw a couple weeks ago.  

Overall, a pretty boring forecast right now...

The Winter:

I have been reading and researching a lot about the forecast for the upcoming winter.  I came across this quote on an Accuweather blog that I thought was pretty funny.

"The models have no idea what to do with precipitation in California this winter."

I feel like that is every winter.  NOAA's winter forecast came out a couple days ago.  Here is a look at their precipitation forecast.

noaa

Pretty similar to a lot of forecasts, and pretty similar to a lot of El Nino winter season forecasts.  It has most of CA in an equal chances category for above or below average precipitation.

Looking at the sea surface temperatures there have been some changes this week.

ssts

The blob is returning and it has shifted a bit East closer to the coast up in the Gulf of Alaska.  The water along the equator near South America has cooled with the easterly winds kicking back in.  That makes the developing El Nino look more like a Modoki with the warmest water in the central Pacific.  And the water off the Baja of CA has cooled a little.

If you remember back to my post last month on the Accuweather winter forecast, they had a ridge in the Southwest bumping the storm track into Northern CA this winter due to the warm water off the Baja.  I checked this morning and they have a recent discussion now unsure and backing off that idea, with the storm track possibly further south in CA.  

The blob of warm water in the North Pacific is further North and further off the coast than the one we saw in the very dry El Nino season of 2014/15.  The thought is that the ridge will sit over Western Canada and the Pacific NW this winter.  But we may see the storms able to track underneath far enough north to bring rain to CA.

I went through and cross-checked some of the seasons where we had a warm North Pacific and a modoki El Nino.  Interestingly we averaged average snowfall in Tahoe.  December or January, or both, were the biggest snowfall months those years.  The season that stands out is 14-15 that had well below average snowfall even though December was the biggest month that year as well.  Was it because the blog and ridge were centered further South that Winter?  

The other interesting thing is the cold eastern Indian Ocean.  Forecasters think that may cause the MJO (madden julian oscillation) to die out in that area and cycle back through phases 8-1 through the winter.  In a weak El Nino, the MJO can have a bigger effect on the pattern.  We have already seen this loop happening this fall.

mjo

In general just looking at weak El Nino seasons we average 75% of average snowfall at 7k.  But there are a lot of other factors that can influence the pattern, especially in a weak El Nino season.  I can understand why the models are struggling with the forecast for Northern/Central CA.  There are factors in favor of an average winter and others against it.  I will finish going through everything and have my guess out by the end of the month.

Stay tuned...BA

About Our Forecaster

Bryan Allegretto

Forecaster

Bryan Allegretto has been writing insightful posts about snow storms for over the last 15 years and is known as Tahoe's go-to snow forecaster. BA grew up in south Jersey, surfing, snowboarding, and chasing down the storms creating the epic conditions for both.

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