Tahoe Daily Snow

Wild Week Ahead...

Summary

Sunny today with highs near 50. Winds are picking up with gusts to 50 mph on the mountain tops this afternoon. For Monday we may have mostly just clouds and gusty winds to 60 mph on the mountain tops. The precipitation from the next storm moves in late in the day into the evening. Monday night we are expecting rain and high elevation snow. Snow levels sitting around 7500 feet before falling Tuesday morning after the precipitation has moved out. We could see several inches on the mountains above the snow line. Tuesday we clear out with highs in the 40's and continued strong winds as the next storm approaches. Wednesday into Thursday a two part storm, warm then cold, moves through. We have rain and snow for Wednesday into Wednesday night with snow levels 7000-7500 feet, and then falling below lake level Thursday with the storm departing Thursday night. We could see several inches of snow at lake level once it turns over from rain on Thursday, and 1-3 feet of snow possibly on the mountains above 7000 feet. Friday we clear out and then for next weekend the forecast models are at odds on whether we could see a warm or cold storm, and if the storm stays to our North or moves South across Central CA. They are also at odds on whether or not we have a quiet weather week for Thanksgiving or more storms.

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Short Term Forecast

A lot to look at this week which takes my research to put the forecasts together take a lot of time.  That and I got caught up watching Back to the Future this morning as it came on as I was finishing my pancakes.  No Eagles game today so I've spend the rest of the day so far studying these storms.

The good news is that we have an active pattern.  The bad news is that the forecast gets very tricky beyond tomorrow.  So plenty of work to do this week to try and nail these storms down.  As most of you know that have followed along with my forecasts for Tahoe over the last 12 seasons, I don't like to be wrong even though of course I am sometimes as such is the life of a forecaster with the fallible tools we have to use.  But I hate being wrong so I obsess over the details of these storms.  It's also why I get upset when a minor few out there suggest we are paid to hype our forecasts.  It would make no sense because if we were wrong more than right we would lose readers, and mine and Joel's personalities wouldn't be able to handle it.  We track and obsess over our final forecast accuracy.

So... enough babbling... let's get into these storms!  

Storm #1 Monday Night:

Ok, so yes this storm has been slowing and shifting now from Monday more towards a Monday night event.  Other than that not much change as it is a weak storm that is fizzling out as the front pushes South across the region.  The snow levels still look to sit around 7500 feet as most of the precip moves through before falling behind the front by Tuesday morning.  The European model is still wetter than the GFS (double) and pushing more precip to the East side of the lake (quadruple).  Making this forecast fun as always...

Here is a look at the GFS (top) vs the Euro (bottom) on the latest 12z runs.  

gfs top

euro bottom

Zoomed out they look similar with the precip not making it much past Tahoe but if we zoom in on them you can see the wetter scenario the European model has for us.  These models tend to do this with every storm with the European model pushing more precip over the crest into the Tahoe basin more times than not.  Two storms ago the GFS was right and the last storm the Euro was right, which is why I take the average of the two for the snowfall forecasts.

Here is the updated snowfall forecast by Tuesday morning.  The NAM model looks more like the GFS, so I would lean towards the lower end for now, especially for the East side of the lake.

monday night

The clouds and strong high elevation winds should continue Tuesday as there is not much of a gap between storms, only about 24 hours.  

Storm #2 Wed-Thu:

This storm is going to be a headache.  We have warm subtropical moisture being pulled into CA ahead of a strong cold front.  That makes a 1-2 punch of precipitation with the first punch warm and the 2nd cold.  The question as always with these storms is the timing of the heaviest precipitation and the cold air.  Also, with moisture being drawn in off the Pacific the total amount is in question.

The GFS has had some wetter runs, but on the latest runs the European model is almost twice as wet with up to 5 inches of liquid along the crest versus 2.5 inches on the GFS.  Also the GFS brings in the cold front faster interacting with the subtropical moisture faster, and consolidating the timing of the storm with the heaviest precip Wednesday night and much lighter precip Thursday before tapering off Thursday evening.

The European model runs have heavy precip Wednesday night lasting into Thursday evening before tapering off by Friday morning.  Also higher snow levels Wednesday night before falling Thursday.  So let's just look at the precip maps first and then snow levels.

Here is the GFS total precip forecast by Friday morning.

gfs by fri

You can see this storm bring heavy precip much further South down the Sierra as well.  Here is the European forecast.

european

It should be pretty obvious the gray colors and heavier precipitation amounts on the European model.  I'm not really questioning the spillover to the East side of the lake as it should be sufficient with the stronger jet stream and cold front providing plenty of forcing.  Here is a close up of the area on the GFS.

gfs close

and Euro...

euro close

So this is making the forecast lots of fun for forecasters....and then add in the snow level issues.  For my forecast I'm taking the precip average between the models as usual, but what about snow levels?  I have the snow levels around 8000 feet to start on Wednesday and slowly falling through the day to 7500 feet.  Then maybe close to 7000 feet overnight Wednesday night, especially if some colder air approaches aloft and the heavier precip can drag down snow levels, but it could be close.  Then on Thursday the snow levels crash below lake level and stay there through Thursday night.

So here is the updated forecast for this storm.  Now just know that the high end forecast is not coming with a lot of confidence since there is a 2.5 inch difference in total precip among the forecast models.  If the GFS is right we would have to cut these amounts in half.  

wed thu storm

Also, don't forget the snowfall at lake level wouldn't be until Thursday after heavy rain Wednesday night, so don't look for snow on the ground Thursday morning.  That's how it looks right now and of course we have a few more days to dial in on the details of this storm.  But overall it looks exciting, especially for the higher terrain ski resorts!

Also fun to look at the 10 day Euro snowfall forecast and dream, but of course not pasting it up on the wall just yet...

snow

Storm #3???:

Here is where things get really tricky as the pattern sets up for next weekend.  The GFS had a very warm and wet storm yesterday.  Today it is pushing most of the precip to our North with mild air moving in next weekend.  The European model on the 12z run tries to drop a cold storm into Northern CA next Sunday.  So umm... yea....  I will get into the slight pattern differences below in the Extended Forecast.

Extended Forecast

We have been looking at the weather pattern starting next weekend over the last several posts.  Not much has changed as we are looking at a pattern that puts us right on the edge of an active storm track, and the slightest shift in the pattern could mean big differences for us next weekend into Thanksgiving week.

I am going to just put the ensemble mean height forecasts side by side from the GFS and European models so you can see the slight differences.  First the GFS (top) and Euro (bottom) for next weekend.

gfs pattern next weekend

euro pattern next weekend

You can see that the European model has a much less amplified ridge over the West and the trough closer to the West Coast.  That is likely why it is allowing a colder storm to drop into the Pacific NW and Northern CA next Sunday.  The more amplified GFS with the deep trough off the coast is drawing warm subtropical moisture up from the South and on the latest runs keep it mostly to our North and West next weekend on the latest runs.

Then going towards Thanksgiving the same comparison...

gfs thanks

euro thanks

Almost similar differences as the GFS keeps us drier through the week and the European model approaches a storm for Thanksgiving.  We have been looking for a Western ridge to form Thanksgiving week for a week now, but it will be interesting to see how the trough off the coast sets up.  Halfway between the two models is a pattern that could bring up warm moisture, so we will be watching closely.

In the uber long-range fantasy time period beyond 10 days we have the GFS trying to push the trough back towards the West Coast and the European model retreating.

gfs week 2

euro week 2

On a global scale these differences are so slight, but for our weather they can be significant.  I think we have plenty to worry about this week though.

Stay tuned...BA

P.S. This is usually an announcement section link, but I keep getting asked by people if we have an app, and we have had an app for years.  So I wanted to mention it in the post today.  We also now have our own in-house app developer so some exciting things coming to our app.  

Download the OpenSnow Mobile App.

We are also continuing to work with weather model developers to continue to create unique snow forecasting tools on the site not available anywhere else.  Our team are not only all snow obsessed skiers and boarders that live in the mountains, we have experience levels from forecasters up to doctorate degree in meteorology on our in-house or partnership team.  All working to bring the tools you have been asking for to make it easier to get onto the mountains during your ideal conditions!

Just a little PSA from me...thanks for listening...BA

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