Lake Tahoe Snow!

 

 

Finally it looks like we have a couple of decent storms brewing in the Pacific which may affect the Lake Tahoe basin and the High Sierra. At 6500 feet (my home) it is currently raining with a mix of heavy wet snow but it is snowing at the resorts and we should see 4-6 inches today through early tomorrow. Then a much more potent system appears to be forming and will possibly bring significant snow Friday night into Saturday mid-day. How much will fall from this system is in question but after each model run it looks more and more impressive! Right on the heels of that storm is another which may be much colder and more impressive dumping possibly 1-2 feet of snow at the resorts and 10-14 inches at lake level. This event could last from Sunday- Tuesday. It then looks like Lake Tahoe will dry out but the active pattern should continue through the next 15 days with the most impressive storms looking like day 10-15 on the extended. Stay tuned!

Here is the NWS forecast statement for 1/22/09:

Area forecast discussion 

National Weather Service Reno Nevada 

350 am PST Thursday Jan 22 2009 

Short term... 

a relatively narrow but heavy band of rain is moving slowly across 

northern and central California this morning as an upper trough makes its 

way onshore. This band of heavy precipitation is being fed by a juicy 

subtropical connection off the Baja California coast. Snow levels are currently 

around 8500 feet or so...which is pretty normal for this type of 

subtropical tap. Only the highest mountains in our area will 

see any snowfall with this storm...and even then it should be pretty 

wet and heavy. Snow levels are expected to remain high...generally 

above 8000 feet through Friday...before finally coming down by 

Friday night as we get into some colder air. No winter statements 

expected at this time...due to the high snow levels. 

The elongated trough coming into California this morning has split into two 

main vorticity maxima...with the shortwave currently northwest of the Bay 

area being the one of our concern. This wave will lift through 

northern California and into the far northwest corner of Nevada by this evening. 

As this wave pushes inland...the stream of heavy precipitation we are 

seeing on the cal radars will push east across the higher elevations 

through the day and scattered showers across western Nevada. 

There is some good diffluence aloft lifting the deep moisture... and 

models are indicating a band of 700mb frontogenesis from Truckee to 

Lovelock later this afternoon and evening. This low level forcing 

will create a nice band of showers across the Interstate 80 

corridor...with periods of moderate to heavy rain possible. Both GFS 

and European model (ecmwf) indicating this band of heavier precipitation setting up across the 

forecast area...so bumped up probability of precipitation and quantitative precipitation forecast for this afternoon and 

evening in the western Nevada valleys. 

Late tonight and into early Sat morning we will see a Little Break 

in the action as we get some weak shortwave ridging...but with the 

abundant moisture still streaming off the Pacific and into our 

area...scattered showers are not out of the question. 

By Friday...another upper level low will drop in right behind...with 

the nose of a 100kt jet pushing across central California and into the 

Sierra. On top of that...a very nice looking diffluent left exit 

region will setup right over the Tahoe area. Latest models are 

coming up with some impressive quantitative precipitation forecast values for the time period 

between Friday night and early Sat morning as we get a shortwave 

lifting through norcal...interacting with the dynamic jet. This is 

plausible to happen with this deep subtropical moisture tap setup. 

So...upped up quantitative precipitation forecast and probability of precipitation for Friday night and Sat as we get this jet 

maximum moving into our area. If models continue to show this period of 

enhanced precipitation...the forecast may need to go up even more. By 

Friday night...snow levels will begin to lower from 8000 feet down 

to near lake level by early Saturday morning...which could cause 

some travel concerns for the Sierra passes Friday night and 

Saturday. Hoon 

Long term...Sunday through Wednesday... 

models continue to drop energy down along the West Coast for Sunday 

and Monday developing a deep positively tilted trough/closed low from 

the northern rockies back across California. The GFS...Canadian... 

and ec continue to differ in details with respect to location of the 

upper low and timing. 

Generally for Sunday and Sunday night the upper low should extend 

across northern California with the GFS further west...rotating the low 

system off the coast... and the ec inland. At any rate snow will 

increase across the Sierra Sunday and continue through Monday. By 

Tuesday models cut this deep low off from the northerly branch of 

the jet sagging the primary feature west of Southern California. This would 

decrease precipitation across the Sierra Tuesday to scattered 

showers. By Wednesday although again the details differ...northern 

California and western Nevada should be under northerly flow aloft as the system 

moves east. 

Overall expect snow in the Sierra Sunday diminishing to scattered 

showers by Tuesday with Wednesday and later in the week generally 

dry. Snow levels will start out around 5000 feet so Sierra 

precipitation should be all snow. Over the period from Sunday 

through Monday night there could be 6 to 10 inches or so of snow at 

lake level with a foot or 2 at higher elevations of the Sierra. Will 

have to keep an eye on storm organization to determine whether any 

watches or warnings will be needed. At this time it looks like the 

best chance for heavier snow would be Sunday associated with the 

cold front...with generally light snow for the the remainder of the 

early week period. 

For western Nevada valleys...snow levels will start at around 4000 

feet up toward the Oregon border to 5200 feet or so in the 

Reno-Carson areas to 5500 feet further east. The best chance for 

valley snow will be associated with the cold front passage. The ec 

drops the cold front through western Nevada late Sunday and Sunday 

night. The GFS brings it through a little earlier...Sunday afternoon 

and early Sunday night. Except for Surprise Valley would not expect 

more than a dusting to an inch or less for the valleys. 

The coldest day of the week should be Monday but temperatures will 

just be 5-10 degrees below normal in most areas before moderating 

back close to normal later in the week. Jah