Update 3 PM:
The latest models runs have only trended wetter today. The new GFS and European runs have up to 4 inches of liquid along the crest, especially SW near Kirkwood. The new NAM has over 5" of liquid. So the forecast is on track and if anything I would lean towards the high end if the models keep trending a little wetter with each run. Amazing amount of cold air with a storm this wet which will cause high snow ratios and a lot more powdery snow than we normally get from a storm with this much moisture.
Quote from the NWS Blizzard Warning issued today:
"Bottom line. I`ve lived in the Sierra for many years and I wouldn`t try to travel over Donner Summit or drive on highway 395 through Mono County during the heart of this storm." -Zach
Good Advice - travel by tonight if you are coming up for the weekend. Also, follow along with live video updates on the TahoeWeather Facebook page. If you go to the videos link you will see the the live videos I'm posting during storms. Also posting storm updates on the TahoeWeather Twitter page, and Instagram stories on the TahoeWeather Instagram page.
From This Morning:
We can see the low pressure system winding up and heading towards the Pacific NW coast today. It will stall out there into Friday and move slowly Southeast across CA on Saturday.
Way out ahead of the spiraling center of low pressure we will see moisture push into the area by this evening with light snow showers developing. Then the cold front, defined by the sharp cut-off in white cloud tops, will push through tomorrow bringing in the heavy snowfall. Behind the front very cold air will boost snow ratios with the 2nd wave of moisture moving in Thursday night, which will cause the snow to pile up quickly.
We may see a bit of a break Friday with much lighter snow showers and even a break in the action, before the center of the low pressure spins into Northern CA bring a 3rd round of heavier snowfall Friday night. Then lighter snow showers Saturday tapering off by afternoon.
Winds: Winds are light this morning with gusts only to 20 mph. The skiing should be good today as clouds increase and winds don't get strong until tonight. Tonight into Thursday we could see ridge gusts to 100 mph which should keep many lifts closed tomorrow. The powdery nature of the snow will make for white-out conditions. The winds should drop off on Friday with gusts 40-50 mph. So hopefully the lifts can get spinning after they are dug out. We could see gusty winds again Friday night but they should drop off for Saturday.
Snowfall: Light snow moving in ahead of the storm tonight could drop a few inches. The heaviest snowfall is expected Thursday into Thursday night. The snow ratios could start out at 9-12:1 but jump to 15-20:1 Thursday night as temperatures drop into the teens. 2-3 feet falls on the mountains in this 24 hour period. Then on Friday we could have a break with showers confined to the crest with several more inches possible. Then Friday night another round of heavier snow could drop another foot of snow into Saturday morning. Check the individual resort pages for a breakdown of snowfall by 12 hour period.
This is not a really strong storm with an atmospheric river bringing in 10 inches of liquid. That would be a big storm. The media is touting this as a monster storm. What is going to make this a big snowfall producer is not excessive amounts of moisture. It's the cold air and slow movement of the storm that is perfect for making a snow machine that will drop a lot of snow. In a normal strong storm with an atmospheric river we have snow ratios below 10:1. So 3 inches of liquid could be only 2 feet of snow. This storm can take 3 inches of liquid and make it 4-5 feet of snow on the mountains. We saw several storms like this during the record breaking 2011 season.
Taking a look at the GFS and European models for total precipitation, they are within a couple tenths of each other. Of interest is how the GFS, on top, is showing a bullseye SW of the lake near Sierra at Tahoe and Kirkwood. The European model suggests heaviest amounts NW and SW of the lake.
There is no way to really know where the heaviest precipitation will fall. We just have to watch and see now. The latest model runs are continuing to trend slightly wetter with each run, which tends to happen within 24 hours. Taking the NAM, WPC, GEM, GEFS, and EPS models I come up with an average of 3.6 inches of liquid along the crest. The exact same average of the GFS/European model average which I use in the snowfall forecast. Of note though is that some models are higher than that average with the WPC's model showing up to 4 inches, and the NAM up to 5 inches along the crest.
When I'm under forecasting for some ski resorts like the last 2 storms, it's because the wettest models ended up being right. When I forecast I take an average and cut-off the outliers that are driest and wettest. So in some cases where the driest model is right I'm a bit over on the forecast, and if the wettest model is right I'm a bit under. But that is not the norm on average. Just noting that there is an outside chance that someone beats the forecast range below.
Here is the final forecast. I am going to watch more model runs today into tonight. But this will be my final forecast for the total snowfall for the storm we will use to verify the totals Sunday morning. It's not much different over the past week. But it has bumped up a couple inches each day. Overall 1.5-3 feet at lake level, and 2-5 feet on the mountains by Saturday night.
I'm getting a lot of questions about travel. I can't answer them all because we do have hundreds of thousands of individual readers on this page and I can't respond to everyone. Feel free to comment below and a lot of locals are usually happy to jump in and answer questions. There is no way for us to know how the driving will be other than slow with low visibility. One accident can close the highway for hours and so can white-out conditions. So all I can say is travel is not advised past this evening until Sunday. Even though there may be lighter snowfall on Friday and Saturday, the roads will be a mess and the crews will be out trying to dig them out.
After this storm we should have a beautiful day Sunday and cold with highs in the 20's. The nice weather should continue into Tuesday with highs into the 30's. Don't run off into the back country this weekend unless you know what you are doing. Avalanche danger will be high. Stick to the controlled areas that are bombed inside the ski areas. Someone always seems to die in the back country when we get storms like this.
The next storm is sitting off the coast by Tuesday pulling in lots of moisture. It's a slow moving storm that should be much warmer than the ones we have been seeing as it is sitting much further South picking up moisture before moving in by next Wednesday. The GFS is fast to push it through with another decent snowstorm for the mountains. The European model is much slower with another multi-day storm. Here is the 10 day total precip forecast.
After that we could continue to see storm through the 2nd week of March, maybe becoming colder again. There are a few signs we could ridge up the 3rd week of March, but we'll see. Plenty of storms between now and then.