A complicated forecast ahead for the next week and beyond.  We have cold systems continuing to drop down the West Coast bring reinforcing cold air and chances for more snow with each.  Let's break down the weekend forecast by day, and then attempt to figure out the complicated pattern next week.

Friday - Friday Night:

There is a low-pressure system spinning off the CA coast this morning.  That will begin to move into Central CA today through tonight.

This system is not that impressive, and the heaviest precipitation amounts still look like they will move into Central CA.  The ridge winds this morning are gusting up to 40+ mph.  That should continue most of the day and increase tonight into Saturday up to 55+ mph by Saturday morning.  The snow levels are starting around 4,500 feet this afternoon and falling to around 2,500 feet tonight.

We could see some light snow showers later this afternoon with a dusting to an inch of snow possible on the mountains by evening.  Then overnight we could see an additional 2-5 inches of powdery snow by Saturday morning.  You can see the precip amounts are still light on the latest model runs.

Saturday - Saturday Night:

Saturday morning we have one storm leaving and the next approaching.  First thing in the morning the winds could be coming down a little from the departing system and then increasing again in the afternoon from a strong storm approaching.  We will have to watch the sensors, but you may be able to sneak in a decent powder morning before the winds get really strong later Saturday.  We could see ridge winds to 75+ mph by evening as the jet stream strengthens over central CA and the cold front approaches from the next storm.

Expecting lighter snow showers during the day and then increasing snowfall rates going into the evening as the cold front pushes in.  During the day through 4 PM, we may only see an additional 2-6 inches of snow.  Snow levels may rise to around 3,500 feet during the afternoon ahead of the next storm.

Saturday night is when the heaviest snow and strongest winds are expected.  Ridgetop winds could hit 100 mph with heavy snow falling.  Snow levels fall back down to around 2,500 feet.  Snow ratios increasing to 14-18:1 with powdery snow falling that will blow around and making driving visibility low. 

The European model is still showing about twice as much precip Saturday night as the GFS.  The forecast models are in good agreement Friday night into Saturday and Sunday.  The range in totals is largely from how much snow we see Saturday night.  Taking the model average we could see an additional 1-2 feet of snow by Sunday morning. 

Sunday:

The change this morning is that the forecast models are showing the storm moving out faster on Sunday. The winds could fall off significantly by Sunday afternoon which means we may end up with a decent powder day later in the day Sunday.  We may only see light snow showers during the day and the storm could clear out by Sunday evening. 

Snow levels fall to as low as 1,500 feet by Sunday afternoon with very powdery snow falling.  During the day on Sunday, we could see a final 3-6 inches of snow

Storm Totals:

The latest model runs either stayed the same or came down a little for total precip amounts from yesterday morning.  Part of that is from the storm moving out faster on Sunday.  Also, the coldest air with snow levels below 1,000 feet and the highest snow ratios comes after the storm has ended.  The range on the models this morning is a general 2-3 inches of total precip possible along the crest.  The model average is around 2.3 inches.

The average is about the same as yesterday, but the GFS has come down to being one of the driest runs now at around 1.9 inches of total precip, and the European model has come down from being one of the wettest at over 3 inches down to 2.7 inches.  So the average of the two is similar to the total model average.  The NAM has come down a few tenths as well but is still the wettest with up to 3 inches.  That would still bring a high end of up to 51 inches of snow at 8k along the crest.

But using the model average here is my final 48-hour forecast for the storm for Friday night through Sunday.  I have brought it down several inches in line with the latest model trend.  It keeps your expectations in check, and then we can be pleasantly surprised if the wettest models end up being right. 

We can look again tomorrow morning to see the model trend for the Saturday night system.

First Half of Next Week:

The pattern could remain similar through the 3rd week of February with the ridge out around 160w in the northeast Pacific, and a cold trough over the West Coast.

Cold systems look like they could continue to drop down the West Coast through next week bringing more chances for snow.  A weaker system on Monday could move down to our northeast keeping us mainly dry with only a chance for scattered snow showers along with some peeks of sun.  Highs still only in the 20's.

Another cold system could move down the West Coast Tuesday into Wednesday bringing us more snow.  This is where the forecast models start to diverge next week.  The latest European model runs show this system taking a similar track to the recent storms, with cold and heavy snow possible later Tuesday into Wednesday.  The latest GFS runs are splitting this trough with one piece moving down to our northeast and the other digging down well off the coast and merging with a low-pressure system northeast of Hawaii.

The GFS scenario would bring a chance for only lighter snow showers Tuesday into Wednesday.  I have taken the average of the two for the 10-day forecasts on the ski resort pages, showing several inches up to a foot or more for the mountains.  We will have to watch this closely over the next few days to get a better idea of what will happen for midweek.

Even more complications as we go later into next week and into the weekend of the 16th.  Yesterday morning, the European and Canadian model runs were showing the Tuesday/Wednesday system possibly merging with the strengthening subtropical jet stream and pulling warmer air and heavy precip into CA by Wednesday into Thursday.  The GFS was the one showing a cold system dropping down the coast and not merging with the southern system.

Yesterday afternoon the GFS was showing the merging of the two systems and the southern branch of the jet stream going into Northern CA with a strong atmospheric river and insane amounts of rain into the Sierra with high snow levels.  The European and Canadian models started trending towards the original GFS scenario keeping the warm AR into the Southern CA with colder air and lesser amounts into Northern CA.

Then this morning.  The European and Canadian models look like the GFS yesterday morning.  As discussed above, they just show a cold system working down the coast for Tuesday into Wednesday.  Then they show a break Thursday, with another cold system moving down the coast with more snow Friday into the weekend of the 16th. 

The GFS this morning is showing the weaker splitting system for Tuesday-Wednesday as discussed above, and then have the weekend system merging with the warmer system and subtropical jet off the coast, and pushing that into Northern CA for the weekend of the 16th with heavy precip and high snow levels.

For today's post, I was just going to say that I wasn't going to get into it until the picture was clearer.  But then I guess I just made you as confused as the rest of us trying to get a handle on the forecast model runs and what could happen next week.  The part that seems likely is two cold systems dropping down the coast midweek and late week.  The question is how do they interact with the low-pressure system northeast of Hawaii and the strengthening subtropical jet stream moving into Southern CA?

Fantasy Range:

The long-range ensembles continue to diverge beyond 10 days into the last week of February.  That could partly be due to the MJO finally being on the move eastward through the Pacific.  The GFS shows the ridge in the northeast Pacific being replaced by a trough and storms coming in off the Pacific instead of down the coast from the north.

The European model shows the pattern staying similar to this week.  The Canadian model now shows the ridge pushing closer to the West Coast with a drier pattern possible the last week of February for Northern CA.

With the MJO activity forecast to progress east into phase 8, I would lean towards the Canadian forecast right now.  Phase 8 usually correlates to a drier pattern in February.  Then a wetter pattern as it moves through phases 1-3 through the Indian Ocean.  

But who really cares right now?  We have plenty of fun and headaches to deal with over the next 10 days...

Stay tuned...BA

P.S.  I keep getting questions about which hours "day" and "night" are in the forecast.  The forecast models run off of "z" time or Zulu Time Zone, which is the Coordinated Universal Time.  Don't worry about that, just that it runs 8 hours ahead of PST in the Winter.  So 12z on the models is 4 AM, and 0z is 4 PM.  That is the cut-off used in my forecasts and most others for day and night as it ties to the hours on the forecast models for 12-hour precipitations totals.

If you are traveling through the Sierra please use the links below for travel advisories as we do not give our opinions for the "safest" travel times for liability reasons.  You can also follow our I-80 Daily Snow forecast as well.

NWS Reno: https://www.weather.gov/rev/
NWS Sacramento: https://www.weather.gov/sto/
CA road conditions: http://www.dot.ca.gov/cgi-b... (and 1-800-427-7623)
NV road conditions: https://nvroads.com/
OSS weather share: http://oss.weathershare.org/#