Sigh... We knew we may be grasping at straws over a week ago hoping for the models to show a storm then 2nd week of the month.  As of this morning, it looks like we will continue the dry spell at least 10 more days.

Originally we were watching for a pattern change based on the MJO (madden julian oscillation) moving through the Indian Ocean.  On average that forces a change in the pattern to a trough and wetter weather for CA, but not always.  There are lots of other factors affecting the patterns.  

We then saw the ensemble mean runs of the models showing a wetter pattern possible the 2nd week of November, and the PNA pattern was forecast to flip to negative which supported that.  Then a few days ago, we finally saw the forecast models start to show a storm around the 11th consistently for a day or two. 

So we thought maybe our chances were getting better that we would see a pattern change this week that could lead to a storm next weekend, as we went through in the last post 2 days ago.  But, over the last 48 hours, the models shifted back to high pressure over CA next weekend on both the operational and ensemble mean runs. 

Also, the PNA forecast changed as well, showing a brief change to a negative phase this week and quickly back to positive next weekend.

That brief flip in the PNA pattern this week will be the ridge shifting NW away from CA.  That will help to drive some colder air into the Western U.S. this week.  We should see a cooldown through the week with overnight lows possibly becoming cold enough for some good snowmaking.

For next weekend, instead of the ridge shifting further away from the coast with a trough and storm digging into CA as we were seeing, the models now show a deep trough north of Hawaii with the ridge shifting back over CA.

That is the complete opposite from 2 days ago.  That may bring a slight warming trend next weekend and continue the dry weather into the start of the week of the 12th.  So it looks like the MJO may not work its magic this time.  Here is the 10-day snowfall forecast.

Long-Range:

Looking at the model runs the last couple days, it looked like maybe the trough next weekend was just slowing down its arrival until Tuesday-Wednesday (13th-14th).  The latest runs show a flattening of the going into the week of the 12th with the storms moving in just to our North, or maybe far enough South to hit us. 

The MJO is forecast to be active in phase 2 the next 5 days in the Indian Ocean, and there is a lag of a few days for the pattern change downstream over the West Coast.  So I don't know if we can officially say there won't be a positive effect on the pattern this time.

But continuing to push storms out to 10+ days away brings flashbacks of the RRR (ridiculously resilient ridge) years.  There are model runs showing a storm hitting Central CA in 10 days, like on the 0z GFS and European runs.  So we will just keep anxiously watching waiting.

Memories:

I went back and looked at our most recent analog year 2009, and also the snowy 2010 and 2016 seasons.  All three didn't see a decent snowfall until the 20-21st of November.  So we are still early yet.  Historically, snowfall chances increase quickly as move later into the month, especially the last week of November.

I remember in November of 2010 I was hiking up on Northstar around the 18th-19th.  It was warm and sunny with highs in the 50's to near 60 degrees.  It was too warm to make snow and the mountain was all dirt.  Similar to the weather we are having this week.  Then the following 7 days we saw over 100 inches of snowfall on the mountains.  By Thanksgiving weekend the mountains were able to open a lot or all of their terrain.

So things can change fast up here.  We can go from dry and mild to buried in snow within a week.  I've seen it happen many times.  So for now, we wait to see if that is in the cards this fall.

Stay tuned...BA

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