An Overly Wordy Opening Statement:

The dry and smoky weather continues this week as we hope for some sort of relief in the weather pattern. We have been tracking a potential change in the pattern for the upcoming weekend, but the details of what that could bring to the Sierra has been sketchy as the models have been doing their typical flip-flopping as they like to do, especially during the change in the seasons during the fall.

The pattern shift is coming with at least cooler weather and some gusty winds for the weekend, and the possibility of at least some light precipitation as trough pushes into the West. Highs in the upper 70s at lake level will be dropping into the 50s for the weekend.

But what could that mean for preciptation and high elevation snowfall? I promised you some details today now that the weekend is within the 5-day forecast window. I also Tweeted out a promise to look at the details last night on the "TahoeWeather" twitter page. So let's see what we can try to come up with today based on the latest information we have.

In last Tuesday's post, I just came right out and said it, "I'm not buying into it yet" when we were looking 10+ days out at the models suggesting we could see significant precipitation for the weekend. In Friday's post, I walked through the flip-flopping models and reminded everyone why I stick to the 5-day window before looking at any potential storm details. 

Since Friday, the model riding has been a roller coaster with the forecast models going big on some runs with an AR (atmospheric river) of moisture for northern CA. Even Sunday night the Canadian model was going big along with the other models. Some of you were getting very excited!

But by Monday night the Canadian model was back to this...

A lot of wailing and gnashing of teeth from the model riders, and this is why I was hesitant to post until this morning. Any forecasters trying to go out on a limb this past weekend would have been calling for the possibility of a foot of snow or more on the mountains... After 35 years of storm tracking and 15 seasons now chasing in Tahoe, I get gut feelings outside of just looking at the model runs, and looking at the overall pattern you could probably tell by my writings over the at 2 weeks that I was not feeling overly excited about this weekend.

BUT...I am excited about any change in the pattern, the cooler temperatures that will give us that feeling that it is fall, and we will take even the chance for light amounts of precpitation and the possibility of seeing some white on the peaks this weekend! What we do have, more importantly, is the chance to see an improvement in the smoke and fire conditions this weekend, especially for far northern CA and up into th ePacific NW.

The Latest Guidance:

Model riders this morning are seeing some better agreement among the forecast models for this weekend, and reconciling with the idea that significant precip and snowfall are likely not happening. It's still 2020 and expectations for exciting things are still very low... 

What is interesting this morning is that the WPC blended model is still forecasting decent amounts of preciptation for the weekend with up to an inch near the crest.

But looking through the European, Canadian, and GFS models this morning, it is clear the trend for the two systems approaching the West Coast Friday and Saturday. The first system is splits off the coast with a weakening wave moving south into southern CA Friday, with very light amounts of precip possible.

The stronger system associated with a colder trough pushes into the Pacific northwest on Saturday. That will push a cold front through the region by Saturday afternoon into Saturday night. The latest trend on the models is for this trough to not dig as far south down the coast, with the northern Sierra on the southern edge of the precipitation as the system pushes through.

That would bring some clouds and gusty winds for Saturday, we could see 50+ mph gusts on the ridges with highs only in the 40s, dropping into the 30s. So be prepared for wind and colder temperatures if you are hiking the higher elevations this weekend. Definitely use our OpenSummit hiking weather app for the hourly forecast on the peaks! 

Light/moderate rain showers could move in as early as midday Saturday and continue into Saturday night before clearing by Sunday morning. Snow levels start out very high above 10,000 feet, but could fall to near 8000 ft. by Saturday evening, and then bottom out briefly as low as 7000 ft. Saturday night before the system clears the area.

Looking at the deterministic and ensemble models, they show a range this morning of 0.30 - 0.90 inches of total precipitation on the high end, west of the lake along the Sierra crest. With lesser amounts to the east across the Tahoe basin. That is a weak system by Tahoe standards. Here is a look at the latest GFS model run showing only up to 0.3 inches of total precip near the crest.

You can see that the heavy rains stay in far northern CA and the Pacific NW. Then the preciptation moves east into the Rockies. That is also the areas that have the best chance to see accumulation snowfall in th upper elevations.

With snow levels falling on Satuday night, there is the chance we could see a dusting of snow on the peaks. Taking an average of the latest Euro/GFS model runs, here is a look at the first snowfall forecast of the season. It was nice to dust off the calculator this morning even for a piddly system. We could see may an inch or two above 8000 ft. by Sunday morning if the latest model trends hold.

We are still 4-5 days out from this weekend. The system could continue to trend north with a completely dry scenario as the latest Canadian model run suggests, and there is still a little time for trend back to the south again. So we will keep an eye on it the next few days. I'll likely update again Thursday to see where we stand for the potential of waking up to smoke-free skies Sunday morning and a view of a few white high elevation peaks. That would be very nice, and a reminder that winter is just around the corner!

By Monday high pressure is already starting to build back in near the West Coast and could continue to build through next week.

That would bring back the dry weather and a warmup next week. Highs back into the 60s and then 70s for lake level. Even if we only get light amounts of precipitation in northern CA and this weekend and then dry out again in the long-range, the fire danger and smoke may only see a very brief reprieve this weekend.

The long-range models show additional trough trying to dig into the West, but the latest runs keep most of the systems well to our north. It is still early and if we do get significant systems in October, they are usually near th very end of the month. So we will keep watching and updating.

The Winter Season:

Here is a look at the latest SST (sea surface temperature) anomaly map.

You can see that the La Nina conditions are in full effect with the colder water along the equator. We also saw warming off the West Coast this week and cooling between the Aleutians and Hawaii, likely due to a more active storm track. Plenty of warm water in the Indian Ocean and far Western Pacific. The map looks similar to 2016 to me, with the La Nina being a bit stronger so far.

2016 is one of several analog seasons for this Winter, but that doesn't mean the weather will be the same. That fall we saw a lot of rain and some significant snowfall later in October. November with the same with some big snowfall, more than December. Then we got clobbered in January and February.

There is a lot to look at as winter gets closer, and we will dive into the details more as we get closer to winter and the patterns we could see becoming clearer. Of course, we always preach about how inaccurate long-range forecasts are historically in the weather world, especially seasonal forecasts. It's fun to play around with them, but never buy stock in them.

In Closing:

If you are still reading this far down, you are a nerd, and probably ready for this post to be over so I'll end it here. Let's hope for an early start to the storms this year, especially with the amount of fires. 

You have probably seen several ski-related sites and businesses fall victim to the pandemic environment. Some notable ones being OnTheSnow and most recently Powder Magazine. Being a publishing company has become more difficult in the current environment with a lack of companies with the funds to advertise on free print and publishing sites. The reliance on a loyal following to subscribe has and will continue to become more common. 

The offset to that is that our loyal audience will expect a continuation of innovation and new content. So that is where we have been focused all year. We have created all kinds of new features this summer on the OpenSummit hiking app, and are now launching and creating new features for OpenSnow. Most recently with the launch of the "Maps" feature on the OpenSnow iOS app. Lots more to come! If you are a loyal user, please consider becoming an All-Access subscriber, especially before prices go up later this fall!

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Thank you, and stay tuned as we track storms and approach what is hopefully a very active winter season!

BA