Tahoe snow.

[oragejuice]

Another dispute that I need help settling.

I'll spare the details, but I'm wondering... does the Tahoe snow come directly from storms over the ocean? Or do the clouds pick up moisture from the lake and dump it right back on the mountains... like they say it does in SLC?

Hm?

 

[tradygirl]

Tahoe gets the storms straight off the ocean. Tahoe is actually at the far west end of the Sierras, so there are no orographic effects like you would see in SLC (forced lifting of clouds die to mountains). The storms are already high and cold by the time they reach the Lake.

SLC is fortunate enough to be in the sweet spot between the continental (dry, cold snow with less depth = Colorado) and the maritime. This means we get the nice light snow that Colorado gets, but we are also the first to get the storms right after they leave the Sierras and cross the Great Basin, meaning deeper snowpacks. The storms have time to sink to a lower elevation and gain moisture after they leave the Sierras. Add in a gigantic lake to saturate the clouds right before they hit the Wasatch and BAM! You get a warm, moist storm hitting a wall of mountains, rising quickly, cooling off, and dumping moisture.

 

[lisaski]

Sierra ridge squeezes out the moisture

Hi All,

I cannot resist this thread. I am a Californian and I have a master of science in Atmospheric Science.

The driver for lake effect is the moisture difference between cold dry air flowing over a warm moist surface layer of air above a lake. When Pacific storms roll in, they are already saturated air masses. A saturated air mass is not going to pick up much more moisture while passing over an alpine lake at 6200 feet.

On some occasions, when cold, dry air masses coming from the north flow over Lake Tahoe, the lake effect can be an effective snow producer at places like Heavenly Valley in South Lake Tahoe and the back country on the southeast shore of the lake. Lake Tahoe is longer in the north-south direction than east-west. That presents a larger fetch for the northerly winds that come with such storms. Also, those storms do not come directly from the ocean. Hence, the air is dryer and is capable of picking up more moisture from the lake than the saturated air from the Pacific.

The majority of moisture in sierra storms comes directly from the ocean. It's an infinitely larger fetch than that of Lake Tahoe. The Great Salt Lake, on the other hand is a moisture source for an air mass that has already dried out by crossing the coastal mountains and desert of Nevada. So, the difference in the moisture in the dryer air and the lake surface air is much larger. Lake effect is strong in the Wasatch.

 

[CMCM]

Hi All,

I cannot resist this thread. I am a Californian and I have a master of science in Atmospheric Science.

The driver for lake effect is the moisture difference between cold dry air flowing over a warm moist surface layer of air above a lake. When Pacific storms roll in, they are already saturated air masses. A saturated air mass is not going to pick up much more moisture while passing over an alpine lake at 6200 feet.

On some occasions, when cold, dry air masses coming from the north flow over Lake Tahoe, the lake effect can be an effective snow producer at places like Heavenly Valley in South Lake Tahoe and the back country on the southeast shore of the lake. Lake Tahoe is longer in the north-south direction than east-west. That presents a larger fetch for the northerly winds that come with such storms. Also, those storms do not come directly from the ocean. Hence, the air is dryer and is capable of picking up more moisture from the lake than the saturated air from the Pacific.

The majority of moisture in sierra storms comes directly from the ocean. It's an infinitely larger fetch than that of Lake Tahoe. The Great Salt Lake, on the other hand is a moisture source for an air mass that has already dried out by crossing the coastal mountains and desert of Nevada. So, the difference in the moisture in the dryer air and the lake surface air is much larger. Lake effect is strong in the Wasatch.

Thanks for the great information....I've always been kind of curious about this sort of thing! A question for you: Do most of Tahoe's cold snowstorms originate in the Gulf of Alaska?

 

[lisaski]

Great question! Briefly, a storm from the gulf of alaska that barrels through Tahoe will produce high quality, low moisture content powder. But, it won't be as prolific a snow producer as storms that come from the west. Since it comes from the north, it's kind of a glancing blow along the Tahoe ridge as it heads south.

The best situation for epic dumps is when the Alaska storm stalls on the coast and spins the "pineapple express" moisture from the area around Hawaii into the cold air that it drags down from the gulf of alaska and sends it crashing into the ridge of the sierra. Those storms produce three or more feet of snow and usually have 100 mile per hour winds at the ridge.

Lisa