Sun and clouds today with highs in the 40's on the mountains, and 50's at lake level. Tuesday light rain and snow showers expected with snow levels around 8,000 feet. Some heavier precip possible over the passes and along the Sierra Crest. Later Tuesday afternoon and evening heavier snowfall arrives and snow levels drop below lake level. The snow continues in varying intensities through Saturday as several waves of precipitation move through the region. We are expecting several feet of snow to pile up on the mountains by Saturday and a couple feet possible at lake level as well. We could have a break on Sunday, but then a couple more storms could move through with more snowfall next week.
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Short Term Forecast
It's always a good Monday morning when you wake up and this is the forecast your phone is showing!
We have plenty of forecasting fun ahead the next 2 weeks. We will start with the 2nd prolonged snowfall event of the month that moves in tomorrow. For the discussion this morning I copied over a lot from the post last night as there are not many changes other than the forecast models trending a bit wetter with each run.
The storm is winding up off the coast this morning and will be pushing moisture into Northern CA by tonight. Not expecting much in the way of showers until Tuesday morning.
The forecast models are still not in agreement on this storm. Like last night, the GFS is still much wetter than the other models, and has the 2nd round of heavier precip Thursday into Thursday night instead of Thursday night into Friday. Overall all of the forecast models have trended a bit wetter today. For the snowfall forecasts below the higher amounts are for West of the lake near the crest with the lower amounts to the East of the lake.
There is good forecast model agreement through Tuesday night. We should wake up to light rain/snow showers Tuesday morning. At first we have a flow out of the South ahead of the cold front. So good shadowing of the precip East of the crest. Snow levels look to start the day around 8,000 feet.
Here is a look at the GFS precip forecast map through Tuesday. You can see over an inch of liquid on the West slopes of the Sierra, but much lighter precip making it into the basin, especially the East side.
So for most of the day on Tuesday expect light rain showers and wet snow above 8,000 feet. Right up along the crest from Donner Summit down to Kirkwood we could see some heavier precip and slightly lower snow levels with a few inches of snow during the day. Then the cold front pushes through during the late afternoon and evening bringing heavier snowfall and dropping snow levels below lake level pretty quickly it looks like.
The GFS model is wetter than the European model Tuesday night. Taking the average we could see 6-17 inches of snow on the mountains by Wednesday morning, and 5-12 inches possible at lake level.
The forecast models are in better agreement today for Wednesday. They are showing much lighter snowfall during the day with only 1-3 inches of snow. Then Wednesday night the European model keeps the snowfall light, but the latest GFS model run shows a push of heavier precip. The difference would be a couple of inches or several inches Wednesday night.
Taking the average we could see an additional 3-10 inches of snow on the mountains by Thursday morning. At lake level we could see 3-7 inches.
The GFS is still faster to bring in the 3rd round of heavier precip during the day Thursday as the main area of low pressure approaches the coast. The European model has a break Thursday and then brings in heavier precip Thursday night into Friday. With the GFS moving in the heavier precip 12 hours earlier, it has an inch more of liquid during this 24 hour period.
Taking the average we could see an additional 7-17 inches on the mountains by Friday morning, and 6-11 inches at lake level.
The GFS is winding things down as the low spins down the coast and then inland over Central CA. The European model drops the low further South before turning inland. Thursday-Friday is mainly timing differences with the GFS bringing the moisture with the low in Thursday into Thursday night, and the Euro Thursday night into Friday. The European model also keeps the moderate snowfall going into Friday night while the GFS is much lighter.
Taking the average we could see an additional 7-16 inches on the mountains by Saturday morning, and 6-11 inches at lake level.
The latest model runs keep scattered snow showers around before completely clearing us out by Saturday night. We could see an additional 1-2 inches of snow on the mountains.
As you can see there are timing and precip differences each day between the forecast models. Each difference can affect the snowfall amounts for each 12 hour period. In total the forecast models have 4-5+ inches of liquid along the crest by Saturday. The Canadian is the lowest with around 4 inches, the European 4.8 inches, and the GFS now 5.5 inches. The WPC's model which averages several models has up to 4.5 inches near the crest.
This storm is now forecast to have more precip than the last big storm that we saw the first 4 days of the month. It is also a slightly longer duration with up to 5 days of snowfall. The biggest difference is lower snow ratios with the air associated with this storm not as cold as that storm. But with the increasing precip amounts the snowfall forecast is getting close to the original forecast for the last storm. I put the snowfall forecast amounts by day above in bold so that you could see it's only inches of snow per day, but it adds up over the 5 days.
I would still lean towards the low end of the forecast with the GFS about an inch wetter than the other models on the high end. There is still uncertainty with the track of the low for Thursday-Friday. If it tracks down further off the coast then we could see a significant drop in the forecast for the 2nd half of this storm. For now I'm sticking with the general forecast of 2-4 feet on the mountains, but the chance now that we could see up to 5 feet of snow above 8,000 feet along the crest if the current model runs verify.
It looks like Sunday we could have a break but then the next storm could bring in snowfall as early as next Monday.
The trough still looks like it is going to settle in over the West Coast through next week. That should allow more storms to drop down from the North Pacific and bring us some more snow.
The forecast models struggle in the long-range during the change in the seasons from Winter to Spring. There are different scenarios with the storm to start next week. Some model runs have it dropping right down the coast with a quick hit of snow and more systems behind that. Other runs show a slower moving area of lower pressure sitting off the coast pushing in precip with a more prolonged snowfall event next week. Either way we should see more storms next week bringing more snowfall.
There are some signs showing that we could finally see high pressure start to build in the week of the 26th on the European ensemble mean runs.
But the GFS ensemble mean runs keep a trough around and the storm door open...
Over then next 2 weeks we should get plenty enough snow to keep the skiing good into April. More importantly we are trying to continue to put a dent in the big precipitation deficit we racked up earlier in the season. We are currently only around 63% of average to date in the Northern Sierra.
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