Late Sunday Night:

It is subtle, however the newer models runs seem to be developing more southerly flow with this first system Tuesday into Wednesday AM as the system is taking on more of a negative tilt.  So as a result, there is likely to be more shadowing with less snowfall east of the sierra crest. The National Weather Service has dropped the WSW to a winter weather advisory.  The main shot of this precipitation is likely over the sierra foothills and along the south facing exposures, according to this evenings guidance.

A Winter Weather Advisory has been hoisted for Tuesday afternoon beginning at 1:00PM thru Wednesday at 4:00PM

4 to 8 inches of snow is expected in the Town of Mammoth with 12 to 18 inches on Mammoth Mt by Wednesday evening.

Westerly flow returns later in the week with better orographics and heavier snowfall later Thursday into Friday.

This will cut back to some degree the snowfall totals over the next 7 days, however amounts will still be impressive….


Saturday’s light rain and snow did little to enhance the snowpack over the Eastern Sierra. However, that should change as a cold upper low sets up residence over the Eastern Pacific.  Looking the Sunday 18Z GFS, the upper tough was located about 145west with the cold core very large and expansive. So not only is this system cold but it also has a large enough pool to last several days once it gets to the central west coast.

500 MB temps now are at  up to -40C with 700Mb temps into the mid -20sC   Lots of energy!

The upstream ridge behind the cold Trof builds over the top of the system for a while and acts to cut it off. However, not before it is sets up close enough along the west coast! All forecast models indicate that Southwest to westerly flow will dominate the pattern into next Friday! So this storm becomes stationary for a while and that makes it quite unpredictable as far as the timing of the more significant waves of moisture that flow into the sierra at this distance in time. There is a lot of energy indicated by the models behind this trough (trof). The whole pattern is highlighted by a persistent long wave Trof that may last through the upcoming week or longer.  The main message here is that forecasters have been watching this storm for sometime now and confidence is increasing that we will be in quite cold and snowy pattern through this Friday or possibly longer depending upon which model you believe. a good 3 to 6 feet is possible on Mammoth Mt this week with between 1.5 to 3 feet in town by Friday

GFS has next weekend cold and sort of showery Saturday and dry weather possible Sunday.

The ECMWF (Euro) Ensemble has the Trof reloading time and time again with almost non stop snowfall through the 24th. Wowie Zowie!


Here is the long range QPF by both Models for the Central Sierra on Sunday’s model run in inches of water with snow to water ratios of at least 10:1, and at times possibly 13:1 or greater.

  1. GFS:  deterministic 18z Sunday Run the upcoming 10 day period.   7 inches of water in the San Joaquin drainage
  2. ECMWF: 12Z Deterministic has 7 to 9 inches in the SJD
  3. Sundays 12Z ECMWF EPD Control has 7 to 9 inches in the SJD while the 15 day shows some 15 inches!
  4.  The ECMWF 12Z EPD Ensemble mean has about 7 inches

The upper jet approaches our area Tuesday AM and so expect the winds to begin cranking in the early morning.


It is likely to be quite chilly by Wednesday with highs in the 30s but the coldest air will arrive next Friday into Saturday with highs in the upper 20s.


Dr Howard and the Dweebs………………….:-)