Dec 21, 2018
Dynamic Models Showing MJO into Phase 6 Toward end of year….Pattern to shift to inside slider pattern after Christmas, then potentially Strong Upper Eastern Pacific Ridge for a period of time afterwards in early January.

12-19-2018 Wednesday 9:15AM:
Observations and thoughts:
1. MJO now moving into phase space 5
2. Both GFS and ECMWF have it stalling for awhile, supporting the cold in the far west through the end of the year. This supports the idea that the mean ridge position is going to be close enough to the west coast to shut off any meaningful subtropical fetch after Christmas through the end of the year.   WX systems will dig mostly SSE over the far west/SW with little over water trajectory. We are on the cusp of going dry….

If by chance the MJO dives into the circle of death and dissipates….that would be positive for a weaker eastern pacific ridge and better for more snowfall. However, what is likley is that the MJO progresses east into phase 6 (the western pacific), setting up mean ridge position over/near the west coast and putting an end to storms for our area for a period of time. 

So far, El Nino has not coupled with the mid latitude circulation. This is evidenced by little convection over the Nino region. That may be slowly changing as the Dweebs have noticed a flareup just north of the equator  at about 130-135west.  Although quite incipient, if the MJO continues on its easterly track after the forecasted stall, the Dweebs would expect the Nino region to “light up” going into January with strong positive phase PNA implication’s.  This is where it is going to get tricky for California. Where and how the coming upper height structure effects the jet streams. Additionally, a strato-warm event is underway. That argues for a coming cold event with the intrusion of bitter Arctic Air over the east, possibly centered as far west, between the Appalachians and the Tennessee Valley. 
So the chain of events that may take place is that the west will remain cold through the end of the year followed by milder weather thereafter.

In Summery, Small storms with fluffy snowfall will be more likley through years end. After early January, winter may cut off for awhile over the far west. Once the convective stage of El Nino fires up either later this month into January, we are going to see a lot of weather changes across the western hemisphere…..More will be known over the next 2 to 4 weeks………

12-18-2018: The Dweebs have looked over the latest runs of the European and GFS models from Tuesdays 12Z run and come to the conclusion that there will be 3 significant short waves that will carve quite the cold Trof  over the far Southwest. The prind point in the Christmas outlook, is that although the two global models at this point have timing issues and even phasing issues with a couple of the short waves, the upshot is that we have a period of snowfall, beginning as early as Sunday in the case of the Euro model and in the case of the GFS (American models) Monday, that advertise moderate snowfall on and off through the following Thursday. Preliminary amounts show up to two feet of powder.

On Monday night, modified Arctic air will plunge south over the far west giving the Sierra a period of Platinum Powder Monday night (Christmas Eve) into Early Tuesday AM.  If the Euro is correct that snowfall may not be as fluffy, but may start earlier and be more of it.  There is some suggestion that the cold temperatures may begin to modify that following weekend before New years.

MJO:  The active upper divergence portion is currently over the Maritime Continent. It is expected to stall out for a while. In this location, we would expected to continue with an active pattern into the end of 2018. However, January will be interesting, as if it progresses east to the western pacific and central pacific, that favors the positive phase of the PNA. The pacific north American pattern. This usually results in a big ridge setting up over the far west, blocking storms from California. At the same time, the Polar Vortex setting up over New England often brings bitter Arctic air to the east. It is just not known yet whether the MJO will be strong enough and progress into Phase 6-7 or die in the circle of death before hand. 

El Nino:
The tropical waters near the equator are quite warmer than normal now. However, so far the atmospheric convective response has not begun yet. As the MJO shifts west with its upper divergent portion moving into the Central and Eastern pacific, that may jack start the process with an atmospheric convective response, that feeds into the mid latitudes.  Until this happens, we will not know if California will have a wet Nino or dry Nino. However, the time for all that is getting very near….  The CFS is still showing a Modoki set up with cooler SSTA off the Central American coast this winter. 

One thing is for sure, either Dry or Wet, January is going to be a very interesting month I believe from a climate perspective.