Snow Level Drama...

Introducing The Ikon Pass

The Ikon Pass unlocks the most iconic destinations in North America — including Squaw Valley Alpine Meadows. Welcome to the new standard in season passes, on sale now starting at $599 adult and $149 child (when purchased with an adult pass thru 4/9): http://opsw.co/2FQq5OS

I am going to just focus on this final storm today and try to break it down by 12 hour period.  This is a complex storm with many pieces that make for forecaster headaches.  Over the past 4 weeks I haven't had to deal with snow levels.  I forgot how much fun it is to add that into the mix when calculating a snowfall forecast.  The first half of this storm will  be the the ones we saw in November.  Feet of snow above 8,000 feet and no snow at lake level.  

On satellite this morning you can see a few pieces of the storm with the river of moisture moving into SoCal, the low spinning off the coast, and the cold front pushing down from the Gulf of Alaska.

This morning there is precipitation moving in on the radar, but we are not expecting much of that to reach the Tahoe basin until later this afternoon or tonight.

Ok, so let me try to break this down for you...

Today:

Today moisture is streaming in off the Pacific.  We are not expecting much of that to push into the Tahoe basin.  We could see some light showers later today, especially West of the lake along the crest.  Snow levels could initially start below 7000 feet with the dry air in place, but they will rise above 7000 feet by tonight.  Highs today in the 30's on the mountains and 40's at lake level.  Mountain top winds this morning are already up to 50 mph, and should increase into the afternoon.

Tonight:

Tonight we are still expecting mostly lighter precipitation with the best chance for showers along the crest.  Snow levels sitting around 7500-8000 feet.  We could see 1-2 inches above the snow line.

Wednesday:

With the Southerly flow ahead of the incoming low on Wednesday we are expecting the shadowing to continue for the Tahoe basin.  Lighter showers possible in the basin with the heavier showers confined to the crest or West of the crest.  Snow levels sitting around 7500-8000 feet.  We could see another 1-2 inches of snow above the snow line.  Winds increase with gusts to 70+ mph on the ridges.

Some model runs like the European model push more precipitation into the basin, while other like the GFS show heavy precip on the West slope and barely any precip making it into the Tahoe basin.

We will have to see how much moisture makes it over the crest, but the only difference should be a few additional inches of wet snow above the snow line.

Wednesday Night:

Wednesday night is when the heavier precipitation moves in with heavy rain and snow pushing across the entire basin.  The European model in total is about an inch wetter than the GFS, and that is because it has twice as much precip Wednesday night as that low spinning off the coast moves inland.  The issue will be that snow levels stay in the 7500-8000 foot range.  So lots of rain below that causing melting and runoff, and lots of heavy wet snow above that.  We could see 7-13 inches above the snow line.

Thursday:

Thursday things get more interesting at the cold front pushing down form the North stars to feed in colder air, and continues the heavy precipitation.  Thursday should have the heavy precip of the storm as the snow levels are falling, which makes forecasting below 8k very tricky.  It looks like snow levels could be down to 7000 feet by midday, and to lake level by evening.  With the very heavy precip they could drag down a little faster.  We could see an additional 7-11 inches above 7000 feet, and 13-20 inches above 8000 feet.

Winds may gust to 90+ mph on the mountain tops Thursday.  Here is the updated total snowfall forecast for the warm part of the storm through Thursday.

Thursday Night:

Thursday night colder air is moving in and snow showers are firing up behind the front, with snow ratios increasing bringing in some fluffier snow.  The showers may cut-off after midnight.  We could see an additional 1-6 inches of snow, even down to lake level.

Friday:

On all of the model runs there is a dramatic break in the precip from the early morning hours Friday until Friday evening.  You may see the sun come out on Friday and think the storm is over, but it's just a gap between waves.  It will be colder with highs in the 20's on the mountains and 30's at lake level.  It will still be windy as well but the winds should come down from Thursday.

Friday Night:

Friday night another front/wave looks like it will move in behind the front on Thursday and ahead of another low moving down the coast.  With the colder air in place we will see much lighter density snow falling on top of the base building snow from the earlier part of the storm.  We could see an additional 5-9 inches of snow.

Saturday:

Saturday we could see some linger snow showers in the morning from the departing wave and increasing snow showers in the afternoon from the final low spinning into CA.  Only expecting light accumulations or even another break in the action for Saturday, with the winds coming down a bit more and temperatures remaining cold with highs in the 20's on the mountains and 30's at lake level.

Saturday Night:

The forecast models have trended back South with the track of the final area of low pressure moving inland Saturday night.  They now have it moving inland over Northern CA bringing one last shot of snow.  This would be the icing on the cake before we head into Spring weather next week.  We could see final 2-11 inches of snow.

Summary:

The forecast models have been trending wetter with this storm.  I take the average of the GFS, GFS ensembles, Euro, Euro ensembles, NAM, Canadian, and WPC models.  The average this morning is 5 inches of liquid along the crest, an inch more than yesterday.  The European model is wetter with 6 inches.  Most of that is increased precip Wednesday night into Thursday during the warmer part of the storm, but some of that is the additional snowfall added back in for Saturday night.  Here is the WPC's model.

As I keep saying, this is a weak event for the mountains through Wednesday, and pretty much a non-event at lake level.  So you may be wondering where the storm is.  Thursday you will not as heavy rain will be falling at lake level and heavy mountain snows, with snow levels dropping to lake level by evening.  Then you may think the storm is over Friday, and Saturday, but those could be false endings as Friday night and Saturday 2 final waves could drop several inches of fresh powder.

In all this is a 5 day event with many moving parts to watch.  Most interesting day should be Thursday as we watch snow levels all day.  I plan to be on mountain watching closely.  In total the snowfall forecast has gone up for areas above 8,000 feet, but notice the quick drop off below the snow line.

We will have to wait until Sunday to see if we have 2-5 feet on the mountains.  This won't be the waist deep powder of the last 2 storms, but it will be a lot of snow on the upper mountains that will help with the snowpack, summer run-off, and to keep conditions good into April.  There will be ankle to shin deep fluffy powder days possible though Friday, Saturday, and Sunday.

Long-Range:

Next week we are expecting high pressure to build in with a week of quiet weather and highs warming into the 40's.  

The European model shows quiet weather in the extended forecast.  The GFS is still trying to drop a trough into the West Coast again the first week of April opening the door to possible storms.

We'll see...

Stay tuned...BA

Announcements

It's That Time of Year!

We’re conducting our annual user survey.  It would be awesome if everyone could quickly take the survey so that we can get your feedback and make opensnow.com even more awesome next year! 

http://opsw.co/2018survey.

Thank you!

BA

Read More at OpenSnow.com