0600 temp. at 6350’ in Carnelian Bay: 30.4 deg. with 90% RH

New snow: Trace – .5”

Recent Weather Obs.:

After a warm, dry summer – with relatively little smoke – Tahoe weather turned more active over the past week. Today marks the second, barely measurable morning snowfall just above lake level! The shift in the weather has turned my daydreams away from running through crispy golden meadows to resplendent mornings spent floating down mountains stacked in soft, fluffy powder. It’s time to start thinking about snow!

Weather watching over the past few days has really become exciting with periods of high winds, showers, and great lenticular cloud shows, especially at dawn and dusk. Windy and unsettled conditions arrived Sunday, even dropping measurable snow on the highest peaks, especially on the SW corner of the Basin. A second round of cold and unsettled weather fired up snow showers late yesterday (10/28) dropping 1/2″ of snow on Carnelian Bay and more on the surrounding peaks.

Early this morning, a northerly flow coupled with an unstable airmass over the warm lake waters set up a pronounced band of lake-effect snow right over the West Shore!

I expect that Desolation and the Jakes – Rubicon skyline received a few inches from this stationary band of lake-effect snow. Exciting stuff!

Forecast thoughts:

The rest of the week looks to remain unsettled with another trough of low pressure dropping down the Pacific coast from the Gulf of Alaska. This will bring a cool, northerly flow today, before another round of increased winds and chances for rain and snow showers return overnight Weds into Thurs AM, possibly lasting through the middle of the coming weekend. Models diverge on whether the weekend system will skirt our area with more cold air and increased rain/snow chances, or hit us more directly with a burst of precip. as the system drops down the length of interior CA. Halloween night looks cold and wet, possibly snowy.

Around the lake, expect cool highs in the low to mid 40s today through Weds, before cooling off to the lower 40s Thurs through the weekend. Temps in the mountains will cool considerably with elevation, so expect highs in the 30s to below freezing for much of the period. Higher elevations will receive mainly snow coming in as a dusting to a few inches at a time.

Beyond the weekend, the weather looks to warm gradually under a calmer, sunny fall regime with modest high pressure building back over the Sierra.

Early season snowpack tips:

The snow that fell Sunday (10/27) on the mountains fell on bare ground throughout the Tahoe backcountry. As more snow falls this week, it’ll be important to take stock of how much snow accumulates, and where it ends up melting vs. lingering after this cycle. The sun angle is growing weaker by the day and high elevation shady aspects and protected terrain features might not melt out til spring. Should this week’s snow last until the first respectable dump of the season, this could set the stage for basal faceting and instabilities in the snowpack.

So take note and take pictures of the mountains while you’re out. Notice where the early season snow remains continuous. These spots will be the prime areas of concern for early season instabilities once later storms arrive with more appreciable snow.

24-25 seasonal thoughts:

And about those bigger storms later this season… Do I have any predictions for the 24-25 season? In short, no.

Long term models show the Tahoe Sierra in a toss-up scenario for both precipitation and temperatures in the Dec-Apr time frame. Any strong signal one way or another hasn’t shown up. The much-advertised forecast of a strong La Niña from last spring has been lackluster to date, and could even fall into a “la nada” scenario. This where tropical E. Pacific water temps don’t even reach the threshold to be cold enough to qualify for a La Niña.

ENSO (El Niño / La Niña) can be a big factor in Sierra winters, but it is one of several impactful atmospheric and climatic components that determines how much snow the Sierra receives. The atmosphere is incredibly dynamic and our understanding of what drives major weather patterns continues to evolve and change as we try to grasp the effects of continued warming on the atmosphere and oceans. We have so many new tools at our disposal for understanding, modeling, and predicting the weather, especially in the short term. Yet as we continue to learn, the steady warming of the earth’s atmosphere creates impacts and inputs into the global system that are not yet fully understood, much less predictable at seasonal levels.

So at this point, the 24-25 season looks like a toss up. Enjoy whatever comes.