Update 3 PM:

Model runs this afternoon continue to come in wetter.  Pretty amazing.  Only slightly wetter through Sunday morning so still a solid 1-2+ feet for the mountains.  But now the GFS and European models are consistently over 6 inches along the crest for total precip by Tuesday evening.  Even if they only average 15:1 ratios through the storm that is over 90" or over 7 feet. 

NWS Reno pushed the high-end potential at lake level to 6 feet and 10 feet along the crest by Tuesday evening.  That's high end west of the lake.  The GFS now has up to 7 inches of liquid SW of the lake near Sierra & Kirkwood, so at 15:1 that's a high end of 105", and snow ratios could average higher. 

For now, I'm sticking with the forecast below from this morning.  We have time to reanalyze the big storm for Sunday into Tuesday again tomorrow morning and early Sunday morning before it arrives.  Last note is that the heavier snowfall now looks to arrive around midday Sunday lasting into Tuesday.  

Here is a forecast and conditions discussion with Coop from Unofficial Networks on the shore of the lake this afternoon.

Here is my afternoon live forecast update.

From Friday Morning:

A lot of hype now for the storms coming this weekend into early next week.  There is a push for more hype recently with the some of the travel disasters we have seen this season when people try to leave Tahoe during a big snowstorm and the roads are closed.  There's a good reason why the NWS and media are hyping up the storms.  It's to scare people from traveling and to keep them safe which is their job.  Getting here through this evening will not be the problem, but leaving before Wednesday will be.

This morning I am going to break down the storms as best I can so you know the expectations by day, and you aren't expecting the 4-day storm totals by Tuesday night to be on the ground tomorrow morning.

Friday - Friday Night:

A deep trough is pushing towards the West Coast this morning.  An area of low pressure is starting to spin up in the base of the trough.  You can see it in the lower left corner of the image.  Ridgetop winds are increasing this morning, gusting to 50+ mph which will continue today.

Here are the stats as of this morning.  You can see we are close to average for precipitation, snowfall, and snowpack as the next round of storms approach.

If you are watching the satellite today you will see that low spin up off the coast and deepen rapidly.  Then it will be sitting along the coast tonight.  That will bring heavy rain and high winds to the coast and Bay Area.  With the southerly flow ahead of the low, precipitation will have a hard time pushing over the mountains into the Tahoe basin.  Expecting to stay mainly dry today.

The latest trend on the forecast models for this system is to push it in a bit further south than we were seeing yesterday.  Now more in line with the forecast 2 days ago.  Light precipitation this evening may be confined to the crest and west side of the lake.  During the early morning hours, Saturday the precipitation may begin to push in as the cold front approaches.

Snow levels are lowering to around 7,000 feet this evening, and then to around 6,500 feet by Saturday morning.  So snowfall should mainly be confined above 7,000 feet tonight.  By 4 a.m. Saturday morning only expecting 1-3 inches of snow above 7,000 feet, and rain at lake level.  So travel up to Tahoe this afternoon and evening shouldn't be that bad, you may hit chain controls over Donner Summit.

Saturday - Saturday Night:

Saturday morning the cold front pushes in bringing heavier snowfall and dropping snow levels to 6,000 feet, and then to 5,500 feet by evening.  Expecting heavy snow during the day Saturday.  Ridge winds increasing to 80+ mph with the cold front, and then maybe coming down a little later in the day.  We could see 3-10 inches at lake level after the change to snow in the morning, and 8-17 inches on the mountains during the day.

Saturday evening and overnight we should see much lighter snow showers.  Snow levels lowering to 4,000 feet.  The forecast models have only a few tenths of an inch of precip Saturday night.  We may only see an additional 1-3 inches of snow overnight.

With the storm trending slightly further south again, the jet stream is slightly further south Saturday.  Even though we see strong wind gusts of 80+ mph on the mountain tops, they don't as strong as yesterday, and the heaviest precipitation should be focused to our south over the Central Sierra.

The forecast models have trended drier this morning with the first system, more in line with the forecast 2 days ago.  The average for total precipitation amounts near the crest by Sunday morning is 1.7 inches, which is what the European model is showing as well.  The GFS is the wettest this morning, still showing up to 2.4 inches of liquid.  Here is the NAM showing up to 1.5 inches and shows the heavier precip to the south, and to the west with the shadowing under the southerly flow to start.

Here is the updated and final forecast for the first storm.  You can see the amounts have been trimmed back a bit but still, 1-2 feet expected on the mountains by Sunday morning reports. The wettest model run this morning would bring up to 28 inches at 8k on the crest.

Sunday - Sunday Night:

The latest model runs have been slowing the arrival of the next system slightly.  Snow showers should continue into Sunday with the moist flow over the mountains.  But the heavier snowfall moving in with the next system may hold off until later in the day on Sunday.  We may also see some slightly warmer air work in ahead of the next system, with snow level possibly rising back up near 5,500 feet on Sunday, but still below lake level.

During the day Sunday expecting strong upper mountain wind gusts to increase through the day as the next storm approaches.  During the day we may only see an additional 2-5 inches of snow by 4 PM.  We will have to watch the timing of the arrival of the next system the next 2 days because once the heavier snow moves in the travel conditions deteriorate rapidly.

A cold trough digs down the coast Sunday.  By Sunday night the jet stream is over Central CA again with the next wave dropping down the coast into Northern CA. That will push in colder air and draw in moisture off the ocean.  Going into Sunday night through Tuesday it's not just the amount of moisture that will bring us heavy snowfall, but the colder air which can hold less moisture and higher snow levels that pile the snow faster.

By Sunday evening this setup brings in heavy snow and strong winds, which could also bring blizzard-like conditions and whiteouts over the passes.  Snow levels lower to around 4,500 feet.  By Monday morning we could see an additional 6-18 inches of snow.

Monday - Monday Night:

Monday the heavy snow and high winds continue.  We could see an additional 6-18 inches of snow during the day.  These forecasts I am typing each day have the low end at lake level on the east shore up to the high end at 8k along the crest.

Monday night a final wave rotates down the coast.  This continues the snow and brings in even colder air.  Snow levels continue to drop going down to around 2,500 feet.  We could see an additional 6-12 inches of snowfall by Tuesday morning.

Tuesday:

The latest trend on the models is for the snow showers to continue through the day on Tuesday before winding down by Tuesday evening.  The coldest air of the storms moves in on Tuesday with snow level dropping to 2,000 feet.  Then possibly below 1,000 feet at the very end Tuesday afternoon/evening.  

We could see a final 4-11 inches of fluffy powder on Tuesday.

The forecast models have all trended wetter Sunday - Tuesday, more in line with what the European model was showing yesterday.  The average is now up to 3.2 inches of additional precipitation near the crest.  The latest GFS run has up to 4 inches and the European is now up to 4.2 inches.  Snow ratios increase to 15:1 on the mountains Sunday, and 20:1 on Monday.  That will help to boost totals from the liquid totals.

Here is the updated snowfall forecast for the Sunday - Tuesday system.

Storm Totals:

Hopefully, that breakdown helps you with daily expectations.  Saturday and Sunday evening into Monday look to have the heaviest snowfall.  The storms start out slow today into tonight and start warmer, then get colder through the period.  Storm totals of up to 6 inches of liquid being shown on the models by Tuesday evening.

2-4 feet at lake level and 3-6+ feet on the mountains still expected by Tuesday evening.  But not by tomorrow or the next day, by Tuesday evening.  You will start to really feel the storm impacts by Monday morning at lake level.  We could see heavy snowfall into Reno with up to a foot of snow possible and more in the foothills.  So leaving Tahoe in either direction Sunday afternoon onward could be extremely difficult to impossible until Tuesday night/Wednesday. 

The trough looks like it could stay over the West through the week with cold air in place into next weekend.

We may stay dry through Tuesday through next weekend with any storms dropping into the West to our East.

The forecast models are struggling in the long-range.  The MJO is forecast to move through phases 7-8 the next 10 days.  That usually correlates to a drier pattern for Northern CA in February, but transitions to a wetter pattern as it moves into phases 1-3.  We will watch the week of the 11th to see if storms will return through midmonth.

Plenty of snow coming for now...

Stay tuned...BA