The first storm of fall is imminent, and hopefully that is a good thing. With the Mosquito fire actively burning on the west slope of the Sierra, we are choked with smoke in Truckee this week. I woke up to an AQI of 450 this morning. Although this storm is unlikely to end fire season completely, it could give firefighters the upper hand on the Mosquito fire, with 1 to 2 inches of rain currently forecast for the Sierra.
The incoming storm is your typical early fall cutoff low. The meaning of that term is that it is disconnected from the main jet stream and lacks direction. It’s that lack of direction that means this low looks like it will drift down the coast and slowly stream successive waves of rain into California. Some of that rain could be heavy at times, which could be problematic for recent burn scars – including the Mosquito, Caldor and Dixie. Most of that rain will likely fall on the western slopes. The lack of forcing from the jet stream usually results in some rain shadowing on the eastern slopes of the Sierra. That said, I have always said that cutoff lows are very difficult to predict.
At the moment, this is a one and done event. In most years that would make me sad, as my skiing dreams normally start ramping up with the first storm. But there’s a lot of building still to be done around Tahoe. There’s still plenty to be done on the dreaded B2B gondola and the new Red Dog lift over at Palisades. I imagine there is still work to be done around the Chalet as well.
Yeah, I’ve got no pictures or actual updates on exactly where those projects are at as I have been busy with a construction project myself. We’re midway through building an accessory dwelling unit in our backyard. All of my days in the last two months have involved shovels, wheelbarrows, or short trips to Tahoe Truckee Lumber and Ace Hardware. I won’t be able to think much about skiing until this project is dried in. The only reason I have time to write this little piece now is I am dreading the 33° temperature and that AQI my phone is reporting.
The Mosquito Fire and Tahoe
Over the last dozen days or so, there’s been a lot of talk about whether or not the Mosquito fire is the “big one” that could reach Alpine, Palisades and the rest of the north Tahoe region. I know it certainly got my attention as it made that big break up the middle fork of the American River last week. It is the middle fork canyon that has the alignment to bring a fire right into the North Tahoe and Truckee area. The prevailing winds also align with that canyon pretty well.
The King fire burned to the south in 2014, and the American fire burned to the north in 2013. The middle fork area has not burned since the 2001 Star fire. That’s plenty of time for new fuel growth to get established in the middle fork canyon.
Back when the King fire seemed to pose a threat to Alpine and Palisades in 2014, the conventional thoughts were that fire cannot cross the granite crest of the Sierra. That all changed with the Dixie and Caldor fires last year, both of which did cross the crest. If you have ever done the hike from Sugar Bowl to Alpine, you are well aware that many areas of that crest are forested right across the crest.
We have been very fortunate to not have many days of strong wind events during the Mosquito fire. Saturday is going to be a test. As of this morning, the Saturday forecast shows winds to 40 mph before the rain gets here. Yikes. I can’t wait til we can just think about skiing.
Late addition: You should absolutely consider downloading the Watch Duty app for your phone. It’s a convenient one stop source for fire data and air quality data.
Great post Mark. The map of previous fire scars is just what I’ve been wanting to see…very helpful. We all hope the AQI numbers reduce some today, and that the fire does not make a big run (and smoke) with the upcoming wind. The rain forecast is encouraging.
Hi Mark, Thanks for your thoughtful and complete analysis of the long term fire risks.
Really helpful, sir. The variability of AQI – jumping from 15 to 450 in an hour as measured at the Alpine watercraft inspection station over the last week–is freakish. Is it just a shift in the winds? Seems to jump later in the daylight, but not always.
Yes it’s those wind shifts that cause the rapid change. Generally downslope winds overnight clear things out overnight, then daytime heating sends winds back up hill.
What’s the worst case scenario for tomorrow? High winds, embers flying up the middle canyon but 1-2″ of rain snuffing it all out? >fingers-crossed<
That’s something nobody can guess for sure. The only thing to do is know that there is a non-zero chance of that fire breaking this way. Have your go bags ready and pay attention to official alerts.