Our first weather post in 191 days…

We are happy to finally be able to do a report on the possibility of some weather changes moving in for the upcoming week. Nothing is ever a sure bet when it comes to weather, but it’s nice to think about the possibility. Keep in mind the models are all over the place at this time of year as we transition from one season to the next. In this case, they are more uncertain than certain. I’m not sure I used enough qualifiers there!

For almost a week, the GFS has been forecasting a tropical storm, or possibly a weak hurricane, that could move in toward the Pacific coast of California. That’s somewhat of a rare event. These storms generally move out toward Hawaii. Occasionally they will “recurve” and make landfall in Baja California, and rarely, into Southern California. At times the GFS has shown the tropical storm to track as far north as the Oregon border.

That’s probably not going to happen. What’s more likely is that the tropical storm will fall apart and the moisture will get entrained in a cold front dipping down into Northern California, sometime around a week from now. We’re not on the hype train yet, but we are intrigued by the possibility.

Rob Calmark, a respected Sacramento forecaster for ABC10, felt good enough about the possibilities to mention the possible pattern change today.

That said, Daniel Swain at WeatherWest was a bit more cautionary. While noting the trend in the GFS, he also points out that the Euro and other models are handling thing much differently, keeping ridging more solidly in place.

Here’s the GFS from the 0Z run, and it looks promising for the first wet cold front of the fall season. Unfortunately, by the time I am finishing writing this article, the next run of the model at 06Z came out. It shows the subtropical moisture moving west, without getting sucked into the cold front, producing a drier solution. With this system being 7 days out, we’re just getting into the window of believability. We’ll have to see where things are at next Monday or Tuesday before I get too excited.

The longer range winter forecast was also recently released from NOAA. It’s now calling for a 75% chance of La Niña conditions. Generally speaking, La Niña winters have not been big snow producers for the Tahoe area. That doesn’t necessarily mean that there won’t be big storms or good skiing. It usually means that we see longer periods of dry, between less frequent storms. Looking at it visually, NOAA shows a chance of below normal precipitation during the months of December, January and February. Temperatures follow the same pattern, warmer to the south and colder to the north.

In a typical La Niña year, the Pacific Northwest resorts are the winners when it comes to snowfall. If you’re the traveling sort of skier, you might consider a northward trek. The prospects of a drier than average winter could cause a greater number of people to consider deferring their 20-21 pass to the 21-22 season. Will that lead to fewer people on the mountain this season and a greater likelihood of continued operations through the COVID pandemic? Only time will tell. From the fire danger perspective we certainly don’t need another drought year.

I’m looking forward to some wetting rains. It’s time to go wash some cars or plan an outdoor event…

Late addition

In my haste to leave for a bike ride this morning, I forgot the last picture! It just adds more uncertainty to the seasonal forecast. AccuWeather also released their seasonal forecast this week. It also calls for a La Niña winter. But their map shows the wetter than normal boundary right over North Lake Tahoe and Alpine Meadows. So a “normal” winter is entirely possible too.