Powder Forecast – Friday, December 26th, 2025
Ted Schlaepfer CCM —- Mammoth Mountain WeatherGuy
Snowfall forecasts are valid at the Sesame snow course (Main Lodge) for the prior 24 hours as reported in the 6-7 AM morning snow report.
**Snowfall forecast confidence ranges from very low (1) to very high (5)
Sat 12/27 = 5 – 6” (H20 = 0.75” – 0.80”) **5
Sun 12/28 = 0”
Mon 12/29 = 0”
Tue 12/30 = 0”
Wed 12/31 = 0”
Thu 1/1 = 0 – 1”
Fri 1/2 = 6 – 12”
Sat – Mon 1/3 – 1/5 = 6 – 12”
December Snowfall = 57”
December Forecast = ~65”
Detailed 4-day Snowfall Forecast:
Sat 12/27 through Tue 12/30 – No snowfall expected all days.
Forecast Summary:
Short Term (Days 1 – 4):
The current infrared satellite image (below) shows the parent low-pressure system finally moving ashore into NorCal this afternoon. Clouds are also streaming into the Sierra as moist upslope flow continues for a few more hours before ending tonight. Current radar (two images below) and webcams show snowfall is ongoing but should end this evening.
High pressure off the West Coast will build over the weekend and into early next week (image below). The remnants of the current low-pressure system over CA will move well off the coast, where it will meander for a few days. That means fair, dry weather returns Saturday and continues through the rest of 2025.
Long Range (Days 5+):
The longer-range guidance shows a return to possibly snowy weather by the end of next week, with another chance the following week. That is the good news, as there could be possible powder days. The bad news is that the super-duper long-range guidance continued to trend drier since the last post for the middle part of January or longer now.
The latest ECM model (image below) moves a short-wave trough southward out of the Gulf of Alaska toward the end of next week and combines it with the remnant low from this week that will eventually and slowly move back toward the coast around the middle of next week. The remnant low will inject more moisture into the trough during the merge, potentially leading to higher snowfall.
That is evident with the ECM solution (image below) that has around 2” of liquid for the end of next week. The latest run of the GFS doesn’t merge the low-pressure system at all, and the QPF from that model is much lower (see the two images below). The ECM EPS isprettyy close to the latest ECM run and has about 2” of liquid as well, with most of it falling next Thursday night and Friday morning. Current forecast leans toward the ECM EPS solution.
The ECM EPS then moves another short-wave into the West Coast and CA early the following week (image below), and hopefully it will trend farther southward with future runs. The EPS shows about an inch of liquid (see the two images below), so there are certainly powder-day chances that week.
Let’s hope so, because the fantasy range guidance has trended much drier now for mid-January and into the third week of the month. The ECM is drier (image below) versus the GFS (two images below) for mid-month, and both models (images below) are quite dry for the third week.
Taking a quick look at the tropics, the MJO has weakened considerably over the past week and now resides within the unit circle. The ECM ensemble forecast (image below) keeps the signal weak and inside the unit circle for the next month. However, many ensembles have it emerging and amplifying in phase 7, the last part of January.
That means other unknown forcings may influence the teleconnection pattern in January, and we could quickly see a model flip. WG
