Sunday 10:15 AM…

Snow began to fall in Mammoth shortly before 10:00 AM

 

Sunday 9:00AM:

RE: Southern California WX

On the 5th of December, the Dweebs brought all our readers the awareness to a change in the WX pattern for Southern California. The ECMWF indicated a major shift in the long wave Eastern Pacific Ridge westward to north of Hawaii later next week.  This retrogression is very significant as its “current location” between Hawaii and the west coast is responsible for the current storm track, and a drier So-Cal.

The ECMWF is certainly the best in longer range week two forecasting tool. It has been very consistent in this change in bringing the first major storm to Southern CA in years beginning the weekend of the 19th/20th.  A development over the past 24 to 36 house suggests that a relatively deep surface low will accompany this storm centered west of South Central CA.   Since there is a lot of sensitivity about precipitation in Southern California, I will be focusing a lot on this upcoming potential event, that is taking shape in the models for late next weekend into the following week.  To Reiterate…..The EC and its ensembles continue to be consistent for a Major Storm just prior to and through the beginning of the start of Astronomical Winter….There are two storms. The first has the deepening surface low late in the weekend and the second sweeps in behind the first…as we transit through the Winter Solstice….

PS:  Monday Noon 12/14/15

Major Christmas Day/Eve storm in the cards for California….North to South!

 

As far as the current storm now moving into the Sierra; The forecast shows between 5 and 10 inches between 7500 and 8500 feet elevation and 12 to 18 inches over the upper elevations by Monday Mid morning….

 

Dr Howard and the Dweebs……………………:-)

 

Saturday Night:

So-Cal Storms Looking good…..beginning late next weekend between the 19th and the 21st then a series through the end of the year…   ECMWF painting QPF in 2 to 3.5 inches in the coastal mountains with first storm.   Nice surface low spins up as well….

 

Saturday AM:

There will be a break between storms today as a short wave ridge moving in from the NW,  diminishes winds. Over-running cloudiness is expected this afternoon from a system over the pacific northwest and will spread mainly mid and high level warm advection type percip…mostly to the north of our area. However, there is a slight chance of some light snowfall early this evening….   In the higher elevations, the wind will ramp up later today and increase further Sunday as the next short wave digs southeast from the GOA. This system is colder than the last, but not cold enough for a Platinum Powder Alert. Most of the cold air comes in behind the precip.  Moderate snowfall accumulations are expected, with between 5 and 10 inches at 8000 feet and between 12 and 18 inches on Mammoth Mountain. Snowfall ratios will probably be between 10:1 to 12:1 so light snowfall yes…but no Platinum Powder.

 

9:00 AM

Mammoth Mt reporting 14 to 20 inches of new this morning. It is still snowing lightly.  Looking at the updated HRRR another 1 to 3 inches is possible today bringing snow storm totals within the 1 to 2 feet forecasted. Great Job Forecast models!!

It was interesting to note that although the freezing level was 10,500 feet early Thursday morning, it was snowing down 7500 feet. The next storm moving in Sunday morning shows a freezing level temporarily at 10,500 at 4:00AM. Snowfall forecast models show that by the time the storm starts about 10:00AM, the freezing level is down to 9000 ft. Remember…the snow level is usually between 1000 feet and 1500 ft below the freezing level, unless there are microphysical processes going on, in which case it can snow all the way down to the surface like 7000 feet. The main point is that it will be all snow and no rain for the next storm on Mammoth Mt,  Sunday into early Monday AM……  And between another 1 to 2 feet is possible.

The Dweebs wanted to add one more bit of information…..If the air-mass is saturated like in “Subtropical moisture advection”, the Snow Level can be the same as the Freezing level……Again subject to microphysical processes.

 

The Dweeber………..

 

12/10/15

8:37pm update…..

System Digging SE….Open Cellular Cu approaching……Get ready for the cold sector of this storm…..Lots of snow coming later tonight!

 

As usual, our favorite global models have their differences. The Dweebs will comment on these current differences during week two and try to relate them to what may happen in the future.

Just as a quick note….This particular storm was expected to bring rain/snow mix this morning at 8000 feet….  Our daytime high already occurred at 37 degrees at 7:30am. At 9:00 it was  down to 31.  It appears that it will be all snow where it is snowing at the moment with the snow level lowering the rest of the day…..

2:00PM

So far the warm sector has been pretty Wimpy with the leading front now falling apart.  A recent report from Mammoth Mt said that there is 3 to 5 inches of new snow, top to bottom at this time with about .6 of precip.

Looking at the IR motion, a nice pool of Open Cellular Cu is rotating off the Northern CA coast and is now just moving in to the north coast.  There is a nice NW/SE Jet streak developing west of Monterrey, CA.  The system is still digging SE and so I expect the popcorn clouds to give way to heavy snowfall tonight and into the AM hours.  The storm is touted to bring 1 to 2 feet total over the upper elevations by mid-day Friday. I think that we’ll still get there but not exactly how expected. Next storm rolls in Sunday with similar amounts however it will be a colder storm with lighter snowfall.

Based upon all model runs today, the storm track for the most part is north of Southern CA. So-Cal will get clipped with showers, but amounts look light. .25 or ??

12:00 NOON

Eye on So-Cal

I think that better news is on the horizon for Southern CA which was what I was leading up to when I wrote this morning. The ECMWF and GFSX both have retrogression in the cards week two. That means the eastern pacific ridge in this case is going to set up further west so Southern CA can get on with winter.

In looking at the ECMWF 5 day means, Long wave ridges on both coasts combine over the central pacific during the 3rd week of December. This should get the storm track down into Southern California before Christmas.  I can imagine that lots of skier’s and boarders would like to try out their new stuff for the holidays….  Timing wise for you folks down south, calendar “around” the weekend of the 19th. IE (a few days before or after) The long wave ridge is further west and north of Hawaii and that should make a difference. It is possible that a stormy pattern for So-Cal  will last several days….Possible but not in stone….

For the record, it is clear that El Nino has effected the Hemispheric pattern in many ways. First of all, the pattern over the CONUS is flipped from last year. It is cold in the west and warm in the east. The Hudson Bay low has not made much of an appearance yet.  However, I have to say that it is still pretty early for that anyway.

 

Dr Howard and the Dweebs……………………:-)