P.M. Update:

Not much change during the day today.  The European and Canadian models show the precip pushing in during the early morning hours with 8000 ft. snow levels dropping during the day Thursday and near lake level by evening. They continue to slowly increase total precip amounts. The GFS has trended drier and slower.  It keeps the moisture feed to our West until Thursday afternoon and as it finally pushes into the basin it slides the heaviest precip to our South.  The NAM is in the middle.  The forecast from this morning still seems reasonable for now.  Update in the morning.

From This Morning:

Summary:

Dry and mild weather will continue through Wednesday ahead of a strong storm that will move in by Thursday.  Strong winds will pick up Wednesday ahead of the storm.  By Thursday heavy rain and snow will be falling, transitioning to snow down to lake level Thursday night.  Friday snow showers are expected.  Total snowfall will be 2-4 feet for the mountains above 7000 ft., with up to a foot down to lake level possible. A dry weekend and then a couple of weaker systems are possible next week.

Details:

I wasn't feeling much creativity with the title this morning.  Maybe because it's 5 a.m. on a Monday.  Tree hunting went pretty well this weekend.  My son dove head first into the mud 3 steps into the trees because he doesn't know any speed but full on running. But that was the only glitch. 

The forecast models have been changing the details of the storm for Thursday each run, but have stayed pretty consistent.  If you missed the posts yesterday the Canadian model which was holding out jumped on board with the other models.  We will most likely see more tweaks to the details over the next 2-3 days before the storm is finally here.  The main concern for most of you is the snow levels, and rightly so as the speed they fall will make a big difference in snowfall at the 7000 and 6000 foot levels.

This storm is going to be associated with a strong jet stream, and the front is to be pulling in a significant amount of moisture from off the Pacific as it approaches.  Ridge top winds will be strong Wednesday into Thursday with speeds in excess of 75 mph.  That is normal when we get these big storms.  

The European model pushes the precip into the basin after midnight on Wednesday.  The GFS hold off until Thursday morning.  They both have the heaviest precip falling Thursday into Thursday night, with lighter precip Friday before clearing out Friday night.  The GFS shows 2-3 inches of liquid over the Tahoe basin by Friday night, with up to 4 inches West of the basin along the Sierra crest.

The European and Canadian models are even stronger with 3-4 inches of liquid over the basin and up to 5 inches along the crest.  In the foothills even more than that will fall with more much needed rain coming for Northern CA.

As the front pushes into Northern CA on Thursday it will bring colder air into the area and begin to drop snow levels.  Looking at the latest GFS model run it is a little slower bringing in the colder air as compared to yesterday's runs.  It is showing the snow levels initially starting around 8000 ft. Thursday morning, and dropping to 7000 ft. Thursday afternoon.  Then the snow levels drop below lake level sometime Thursday evening between 4 p.m. and 10 p.m.  The European run last night was similar to this.  The details may change but we can look at what that might mean for snowfall.

The heaviest precip look like it will fall Thursday, but still heavy Thursday night, and moderate amounts possible Friday.  Above 8000 ft. the temperatures drop into the 20's by Thursday night and the snowfall forecast is much easier with it being all snow.  Above 8000 ft. we could see 2-3 feet, with up to 4 feet West of the basin along the crest.  That is using the more conservative GFS precip amounts.  If the European and Canadian models are correct we could see more.  The NWS put out an advisory this morning for "multiple feet" above 7000 ft. which is vague but understandable being 3 days out and not know which precip forecast will be right and how fast snow levels fall.  

At 7000 ft. we may see up to two-thirds of the precip could fall as snow, so 1-2 feet may be a good guestimate this morning, with more possible West of the basin.  At lake level and just below in Truckee where none of us ski but seem to care most about the snowfall, we may see up to a third of the precip fall as snow later Thursday night into Friday.  That could bring 6-12 inches with slightly higher amounts possible West of highway 89.  So that is my best guess this morning looking at all the details.  The mountains should do much better on the lower half than the last storm if the snow levels can drop to the bases by the end of the day Thursday.

By the weekend we will dry out with colder air in place.  Should be a decent weekend for early season skiing.  I am not sure if I will be able to get on the hill Friday as I am pretty busy with the day job, but I plan to be on the hill all weekend testing out the knee.

Long-Range:

It looks like we could stay in a pattern that would allow more systems to move into the West Coast next week.  The ridge looks like it will stay in Eastern Canada and North of Hawaii.  The forecast models show a weaker storm moving in Monday and again Friday next week, with the GFS trying to sneak in some precip Wednesday as well.  So the weather may stay unsettled next week with more chances for light snowfall accumulations.

Going into the Christmas week the models are all over the place, but the consensus is that we go into a drier period.  Maybe a colder one as well.  The CFSv2 climate model shows increased precipitation again towards the end of the month into January.

Stay tuned....BA