For those not in the know, Mammoth Mt puts on every year, the best fireworks show in December…and in my opinion, better then any show on the Fourth of July anywhere in Eastern Ca.  It’s Mammoth Mt’s way of saying, “Let The Winter Fun Begin!”  If you missed it this year, mark you calender to be up here next year. It is usually displayed the weekend before Christmas. It is a fireworks show bonanza that seeming goes on and on and on, with the back drop of the sierra flashing in the night sky.

The Dweebs checking in with some of their long time local ski instructor friends. They are saying that the skiing is great! Lots of terrain open now with good coverage by “Man Made” snow. The snow guns will continue to pile it on every day of this. Mammoth Mt is touting that they have 15 lifts and the greatest number of runs open, 36+ in California….with the mountain skiable from top to bottom to all three base lodges!

Pretty awesome!  The weather outlook is calling for the conditions to remain favorable for snow making every night and during many of the days as well up until Christmas Eve.


The Dweeb Report:

Week 1..

We are still experiencing one of the driest Decembers on record. WSFO Reno said in a climate discussion Sunday, that if they do not have any measurable precipitation through the end of this month that it will be the 6th time that has happened since 1870. There were 5 completely dry Decembers between 1870 and 1883. Currently not even a trace has been recorded at Reno Cannon AP.  So, if it continues that way, that will be included in the record books for a climatic phenomenon not experienced since 1883, or some 128 years ago! 


The forecast is for a continuation of the present pattern with two, possibly three minor impulses expected to effect California this week. The first is a coastal slider that will form a very small closed low off the Ca coast by Monday evening. There may be a few showers along the southern coastal sections of Ca Tuesday Am with some damp commute areas for motorists deal with this afternoon in Southern Ca. The net effect for the  southern central sierra is for windy condition to redevelop over the crest Monday into Tuesday morning with another shot of cooling for the high country. We gotta have that in this current dry pattern. High temps will cool back into the 30s Monday into Tuesday for great snow making weather!

One more impulse is expected to take a more eastward drop through the Great Basin Thursday with yet another “Possible Great Basin Digger” Friday into Saturday Am.  This Friday’s into Saturday’s impulse is shown by the new 12z Sunday ECMWF and the 12z GEM as being further west and more of a digger into the Great Basin. The 12z GFS does not have that system effecting the Sierra as it is a bit quicker in progressing the long wave ridge into California than the other two. The Dweebs like the idea of one last Short wave bringing cooling and offshore flow Friday into Saturday along with one last shot of cooling for the high country before, “The pattern changes”.

Week 2.

Now that leads us Dweebs into the Christmas to New Years home stretch………….

It is very apparent that the long wave ridge that has been parked far enough off shore to keep the WX colder than normal here in the high county is going to progress east into California Christmas Day, and remains parked there for sometime. The will set up a much milder pattern for the Sierra with above normal temps….and periodically, very strong temperature inversions. Air quality concerns will highlight our weather here in Eastern California was well as the Great Valley to the West. So, if you do not have an EPA wood burning device ,chances are, open fireplace burning will be curtailed at times, the week between Christmas and New Years.

The Global Forecast System is forecasting a series of pacific short waves that will flatten the ridge from time to time with west wind over the crest. It is possible that some of those winds could mix down into the resort levels which could help air quality. However, given the time of year, it is doubtful that the winds will get down into the colder valleys of Eastern Ca until later in the week. It may be a chilly week for Crowley Lake between Christmas and the New Year if the inversion does not break.

Again, this is a dry pattern for the Central Sierra through year’s end. And….although the models are still flirting with a system around New Years Day, that phantom storm that is still showing up in the latter runs of the fantasy charts is not being taken seriously at this time.

More on that later……


Climate Models:

Current Teleconnection Signs;

AO is strongly Positive

NAO is Positive

PNA is weakly negative


So when will the weather break and become stormy?  There is still Strato-Warming forecasted in the models over the next 240 hours. Simply explained; when stratospheric warming occurs in the area of the atmosphere above where the storms are IE (where passenger jets fly), the response to the lower atmosphier is cooling. This cooling works its way south into the mid latitudes and can lead to blocking which paves the way for the transport of cold arctic air into the mid latitudes. There is a correlation with Strato-warming and the shift from a +AO to the -AO.   “The Arctic Oscillation” or AO is currently in its positive phase leading to a lack of cold air in the Midwest. The NAO, North Atlantic Oscellation has also been in its positive phase. During a +NAO you do not have the kind of blocking that delivers persistent cold Arctic air into the US. The AO and NAO often times team up together. Currently with both Teleconnections in the positive phase, storms across the country pretty much progress eastward quickly and are not accompanied with the kind of cold that makes for the big winter storms in the east. Additionally,  when the -NAO teams up with the -AO, it makes for the coldest winters in the eastern CONUS.

The +AO is usually associated with dryer then normal conditions in California…and although there is not any definite correlation to wetness in Ca from just a -AO, the heights over the Pacific Basin are lower and so there is much more storminess off the west coast. So possibly when you add the effects of the -PDO (Pacific Decadal Oscillation) you might be able to make the case for a bias for wet in California when the PNA teleconnection is significantly negative.

Again….When will the Pattern Turn Wet here in Central Ca? Best Guess at this time, the week between January 8th and the 14th. Why?

See the *CFS v2 Weeks 3 and 4.  Updated for the 17th of Dec.



500 HPa Heights:

Note: *The CFS version 2 was developed at the Environmental Modeling Center at NCEP. It is a fully coupled model representing the interaction between the Earth’s oceans, land and atmosphere. It became operational at NCEP in March 2011.


Dr Howard and the Dweebs…………………………..:-)











Reference Glossary of Weather Terms
Disclaimer: I have been a hobbyist meteorologist for over 30 years here in the Mammoth area and I do this for my personal enjoyment. The National Weather Service saves lives every day . . . I do not. When making important planning decisions please use information provided by the National Weather Service as they are the most knowledgeable and accurate information source available today.