We have a lot to talk about today. We have snowfall reports from the Friday system, and snowfall forecasts for the storms lined up to move into CA over the next 7-10 days.

Snowfall Reports:

The cold system moved through Friday and brought snowfall amounts within the forecast range of a dusting up to 3 inches around the Tahoe Basin by Friday evening. Sugar Bowl had close to 3 inches on the stake by Friday afternoon as the steady snow shifted south of the lake and we saw some sun.

We were watching for scattered snow showers Friday night, and we saw one small band of steady snow form NW of the lake from Sugar Bowl down to Squaw/Alpine and Homewood. 

That dropped an additional 2-4 inches of snow in that area overnight. Sugar Bowl clears the snow stake at 5 PM, and as of 5 AM this morning there was another 4 inches on the stake.

That lines up with their 24-hour snowfall report this morning of 7 inches, and down to Squaw and Homewood we have reports of 4-7 inches. That is more than double the 1-3 inch forecast for the storm. The rest of the region came in within the 1-3 inch forecast.

Here is the forecaster scorecard for the storm, with 9 ski areas coming in over the forecast. 

Saturday:

In yesterday morning's discussion, we talked about watching for a band of snow to rotate down from the northeast around the north side of the low Saturday morning, but the model runs were showing it hitting south of the lake. After the post, the models trended farther north. I posted an update on that yesterday on the Tahoe Weather Twitter page showing our forecast radar with the band sweeping down the east side of the lake, almost identical to what radar is showing early this morning.

That is bringing snow showers this morning to mountains on the east side of the lake, so we could see an additional coating to an inch of snow on the reports for Mt. Rose down to Heavenly. That band shifts south through the day with clearing skies. We should see mostly sunny skies throughout the day with cold temperatures. Highs in the 30s at lake level and 20s for the upper mountains.

Sunday - Monday Storm:

We may see partly sunny skies Sunday morning, but then increasing clouds into the afternoon as the next cold system approaches. Highs in the 20s & 30s again. Ridgetop winds may only gust up to 30+ mph this weekend. The latest model runs show that very light snow showers could start to move in during the afternoon.

The steadiest snow is expected Sunday night into Monday as the low moves down through CA from the north.

This system brings in even colder air than the Friday system. Highs only in the 20s for lake level Monday and teens for the upper mountains. Scattered snow showers may linger into Monday evening before clearing out overnight. Again, this is not a windy system. Total precip amounts across the models are zeroing in on around half an inch along the crest.

Snow ratios will be high with this system, running around 15-20:1 on the mountains. That will bring powdery snow and the high snow ratios will help to fluff totals with only 0.25 - 0.5 inches of total liquid falling. There is a chance again that we see a snow band form over an area that brings more snow than forecast, but taking the model average here is the snowfall forecast for this system.

Tuesday - Thursday Storm:

The next storm is on everyone's mind with all of the hype that is being generated around it. This system is straddling the 5-day window being a 2-day storm with Thursday in the 6-day window. I don't like going out more than 5 days because of model accuracy, especially with the snowfall potential we are going to discuss, but here we go!

We should see dry weather most of Tuesday. It could be similar to Sunday with partly sunny skies in the morning and increasing clouds through the afternoon.

There is a pool of moisture north of Hawaii that storms moving across the North Pacific this week are going to draw moisture from...

...and with the trough centered over the West Coast, these storms will spin up along the West Coast and will direct a plume of moisture somewhere along the West Coast. The question is where and for how long. Tuesday night into Wednesday low pressure is off the CA coast with that moisture plume aimed at the northern Sierra.

We will have plenty of cold air in place as this storm moves in with low snow levels. We could see snow begin by Tuesday evening with heavy snow likely into Wednesday. Then as the trough and associated low dig farther down the coast Wednesday night into Thursday the moisture plume shifts south. This is where the forecast models start to diverge.

The European and Canadian models suggest the moisture stream shifts towards the southern Sierra with much lighter and scattered snow showers Wednesday night into Thursday, and light snow Thursday night as the low moves through central CA. The ICON & GFS models suggest the moisture stream only shifts into the central Sierra near Mammoth Wednesday night, and then as the low digs off the coast it actually draws it back north aimed at Tahoe Thursday.

Those 2 scenarios are giving us total precip amounts of only around 3 inches near the crest on the European and Canadian models, with the heavier precip to the south...

...and more than double that with over 6 inches of total precip on the ICON and GFS models.

That is going to make a big difference in total snowfall amounts but both scenarios bring us a decent storm with snow measured in feet not inches. I had someone comment that I shouldn't show different scenarios and just say what I think will happen. The weather doesn't work that way. There is no way to know what will happen, and the best we can do is take an average of the models like our ski resort pages do with the snowfall forecasts.

The WPC's blended model shows around 4.5 inches near the crest. That is close to the total model average I'm coming up with this morning of around 4.25 inches.

This storm will draw in some warmer air, but it doesn't look like enough to raise snow levels above lake level at any point. The highest I'm seeing is around 5500 ft. Thursday on the GFS as the moisture plume shifts back north. Snow levels may start around 3000 ft. Tuesday night and then sit between 4500-5500 ft. through the rest of the storm. Snow ratios may average around 14-15:1 at 8000 ft. which is pretty high for a wet storm.

The ICON & GFS models showing close to 7 inches of liquid, and snow ratios up to 15:1 on the upper mountains, which is why you are seeing big snowfall amounts on the models and around the weather world. You can do the multiplication and see that gets you around 100 inches of snow in a 48-60 hour period Tue Night through Thu Night. The drier models show only up to 37-44 inches. So do we get 3 feet or 8 feet on the upper mountains???

Hopefully, we can hone in on a better agreement with what happens with the moisture feed and where it is aimed over the 2 days. For the initial snowfall guestimate, all we can do is take an average of the models which give us around 3-5+ feet on the mountains, and 2-3+ feet at lake level.

It's always scary throwing out big snowfall forecasts 5 days out. Like I tell my friends, "being a snow forecaster is all fun and games until you have to sign your name at the bottom of the forecast". We have a decent storm on the way I'm pretty confident in that, but not confident on the snowfall totals until we get better agreement. The winds will be strong Wednesday and possibly Thursday with the jet stream aimed at teh Sierra. Ridgetop gusts to 70+ mph. A classing Sierra storm day.

We may see a break Friday, but the GFS model has some straggling snow showers. Then Friday night into Saturday the models now show another system could move in with light-moderate snowfall. That is ahead of another low digging down the coast that could direct another moisture plume at the Sierra by next Sunday into Monday.

That is over a week out so we will stop right there and not get into any details. Always low confidence in storm tracks a week or more out. But I'll just say that the Canadian model has trended back south with the storm track in line with the other models. So there is good agreement right now that we could see more storms next weekend into early the following week.

Fantasy Range:

The long-range models are creating quite a bit of hubbub among model riders as they show insane amounts of total precip over the next 10-11 days. The GFS has had several runs now showing up to 20 inches on the West Slope of the Sierra.

BTW, I put the Tahoe Weather Nerd store back up yesterday if you want a "Model Riders", "Hype Train", "I'll Believe It When I See It", or "Where's the Crest?" shirt.

Those insane precip amounts are showing insane snowfall amounts on teh models. So if you hear a friend talk about 100'-200" in Tahoe over the next 10 days, that is where they are getting it from. This total is out in the "Fantasy Range". So we have a lot of work to do to see if these storms dig into the trough just right, they could miss to the north or south. Either way, just the suggestion reminds us of how fast things can turn around here in Tahoe.

The long-range models still suggest the trough shifts east during the 1st week of February with high pressure build in near the CA coast.

The mean ridge is centered in the Eastern Pacific away from the coast on the European and GFS ensemble mean model runs. The PNA pattern is forecast to trend back closer to neutral but not positive.

So it looks like a drier pattern but not a warm pattern, and maybe not completely dry. But if the wetter model solutions for the next 10 days actually become a reality, your shoveling arms will want a break. 

The MJO forecast still shows the active phase strengthening into phases 6 & 7 in the Western Pacific into the 1st week of February. Those are drier West Coast phases during February. 

It will be interesting to see if the strengthening continues and the active phase moves east through the Pacific during February, and if that could affect the pattern in a positive way for the West Coast. A weakening La Nina and shortening wavelengths later in February usually keeps the pattern more progressive as well.

Stay tuned...BA

P.S. You may remember when Mike Korotkin guest wrote for me last month. He did a great job. So good that he is now our Southern California snow forecaster! You can read his posts about the snow coming to the SoCal mountains at the link below.

https://opensnow.com/dailysnow/southerncalifornia

Also, if you plan to travel through the Sierra this week, be sure to stay tuned to the I-80 Daily Snow.

https://opensnow.com/dailysnow/i80

On this week's show, we review the snowfall reports for each ski region, we talk about the change to colder/snowier weather, and we sit down with Ben Taber our Software Engineer to talk about the new changes to our snow forecast formulas, and more! 

Listen below via Spotify or wherever you get your podcasts. (Apple, Google, Amazon, etc.)