From Ted Schlaepfer CCM  —- Mammoth Mountain WeatherGuy

Tuesday, December 3^rd, 2024 – The Next Discusion Update will be Friday Afternoon

Short Term (Days 1 – 4): The current infrared satellite image (below) this afternoon shows a weak low-pressure system positioned in Arizona and a large high-pressure ridge over the PacNW.  A couple other weak low-pressure systems entering the eastern Pacific will bump into the ridge and move well north of California.

  The high-pressure ridge will remain mostly in place over the next 4-5 days (image below) before shifting slightly southward toward the end of the week and early weekend.  That means continued dry weather and warmer temperatures on Friday and Saturday, with freezing levels around 12K on Saturday.  Winds will remain light this week.

Long Range (Days 5+):

   The longer-range guidance favors dry weather to continue through next week before a possible pattern change just before mid-month. That could lead to a return of snowfall at times into the third week of the month, although it doesn’t look like a storm cycle right now, maybe just a single storm or possibly two.

  The models favor an inside slider-type weather system (image below) to move southward through the Great Basin around Monday next week. No snowfall is expected other than maybe flurries, but it would produce colder temperatures for a day or two before fair and warmer weather returns in mid-next week.

  The ECM model then develops a long-wave trough along the West Coast at the end of next week (image below) and moves it inland over the following weekend (see cover image).  The GFS ensemble (two images below) also has a trough along the West Coast during the same time period, although it is not as deep as the ECM deterministic run.

  The ECM 12z deterministic run shows just under an inch of liquid precipitation (image below) for the primary 48-hour period of snowfall, which would result in over six inches of snowfall at Main and enough for powder conditions. The ECM ensemble mean (two images below) has over an inch of liquid for the period, or about a foot of snowfall. It is still over ten days out, so hopefully, the models will trend wetter as we get closer.

  Beyond that time frame, the unreliable model guidance is primarily dry.  However, the models are suggesting the MJO will move eastward into phase 7 (image below) over the last week of the month, and analogs favor above-normal precipitation for that period.

We will have to wait and see if the model guidance catches up or whether some other forcing (i.e., stratospheric circulations) is the dominant mode for the teleconnection pattern in the northern hemisphere at the end of the month. W.G.