Nice Fall weather is upon us. Lots of sun and seasonal temperatures. We may see a shot of colder air Sunday and again next Friday. Not seeing any appreciable snowfall in the forecast quite yet, but it won't be long hopefully.
We have all been jealously watching the snowfall forecasts and reports for Colorado and Utah. You can find a lot of content on our other pages here on opensnow.com or on the opensnow social media channels.
Meanwhile, here in Tahoe I have been looking at the short term forecast for any signs of more snow, or a change in the pattern. I have also been out and about enjoying the Fall weather around Tahoe and posting to the tahoeweather social media channels. I plan to do a lot more posting this Winter so be sure that you are following along on Facebook, Twitter, and Instagram.
We have a pattern so far this Fall that looks similar to the pattern we may see this Winter. The storms are moving in well to the North and dropping down over the Rockies. We may see another cold trough drop down from the North and then to the East Sunday night that could bring another brief shot of colder air.
Another cold front may move down the coast from the North next Friday the 13th. It may just bring some cold air but could also bring some light snow. So we will be watching that over the next week.
Still not seeing anything significant as far as precipitation or snowfall over the next couple weeks, but that won't be the case in the Northern Rockies as they may continue to see some snowfall. We will continue to enjoy the Fall weather with shots of colder air to remind us Winter is just around the corner.
Some of the climate models like the CFSv2 are showing the chance for more precip making it into Northern CA as we go into November. But overall they show a below average precip month for October and November. Last year we had an early start to the big storms. Not seeing that for this year right now, but with the shots of colder air we may be able to start making snow at the mountains soon.
I have been continuing to watch things line up for the upcoming Winter season. I did put together my own analog forecast like I have done in the past years by scoring past years that have similar conditions to the forecast for this year. I look at the La Nina and its strength, the PDO state, the QBO, the Northern Pacific SST's, etc. The highest scoring years right now are 74-75, 83-84, 84-85, 95-96, 00-01, and 11-12. I talked about 95-96 and 11-12 in the last post.
4 of those seasons were below average snowfall with 80-89% of average snowfall on Donner Summit, and 2 were average to above average with 100-120% of average. The average for all 6 is 92% of average. Looking at just the weak La Nina, the PDO, and QBO as factors the average for all seasons that match this year's forecast is 88% of average snowfall. That makes sense as 4 out of 6 analog seasons are 80-89% of average snowfall.
This of course is based on a weak La Nina with some forecast models showing the possibility of a moderate La Nina, which means we would have to start all over again, but for now weak is still the latest official forecast by NOAA. My initial thoughts in early October looking at the forecast models and at the seasons that match the closest historically, along with the current Northern Pacific sea surface temps, is that we could be looking at 80-90% of average snowfall this Winter.
Last year I was starting low at 85-95% with a similar history of weak La Nina's in a warm PDO with West QBO showing 88% of average snowfall. I did mention the possibility of Atmospheric River events being the wild card last year, but never expected the amount or strength of the ones we saw. After last season with 140% of average snowfall the average for seasons with some of those conditions has now jumped to 99% of average snowfall historically. This year the QBO has flipped so it isn't giving last year as much weight as years like 95-96. I'm still liking that year the best I think looking at everything overall, which had 80% of average snowfall.
The forecast models as well as some of the early forecast coming out of weather outlets this Fall seem to be agreeing. The heaviest snowfall may be from the Pacific NW into the Northern Rockies and maybe into the Northeast this Winter. My early thinking is that we could see total precipitation at a lower average than the snowfall with colder air and colder storms from the North and storms possibly backing in from the East this Winter bringing higher snowfall ratios.
Atmospheric River events are still possible this Winter as the wildcard, but the amount we saw last year is the exception to the norm. So to see something like that 2 years in a row would be amazing. For now I'm only expecting the possibility of colder air and colder storms with below average snowfall. But that snow could be fluffier than normal and stick around awhile if we get the colder air. Then, I will continue to pray that we get more than expected like we did last year.
There is plenty of time for things to change as we get closer to Winter, and these insights are only based on historical data which is limited and not always very accurate. So all we can do is put out a forecast and see how it ends up in the Spring.
For now enjoy the beautiful weather and all the fun events happening around the area this Fall. It won't be long before we are making turn, at the very least on man-made snow!
Stay tuned...BARead More at OpenSnow.com