Powder Forecast – Friday January 31st, 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 2/1 = 4 – 5” (H20 = 0.50” – 0.65”)**3
Sun 2/2 = 2 – 4” (H20 = 0.75” – 1.25”)**2
Mon 2/3 = 0”
Tue 2/4 = 2 – 4” (H20 = 0.25” – 0.35”)**2
Wed 2/5 =32 – 42” (H20 = 4.00” – 5.00”)**2
Thu 2/6 = 0 – 2”
Fri 2/7 = 4 – 6”
Sat – Mon 2/8 – 2/11 = 3– 6”
January Snowfall = 10”
January Forecast = 10”
Detailed 4-day Snowfall Forecast:
Sat 2/1– Light/moderate snowfall during the morning/midday, becoming a rain/snow mix by late PM and evening, ending at night. Rain on the lower part of the mountain. Accumulations 2 – 4” at Main by Sunday AM and 8”+ up top.
Sun 2/2– No snowfall expected.
Mon 2/3– No snowfall expected during the day, then snowfall likely develops overnight. Accumulations 2 – 4” at Main by Tuesday AM and 6”+ up top.
Tue 2/4– Heavy snowfall develops during the day and continues through the evening before ending overnight. Accumulations 32 – 42” at Main by Wednesday AM and 45”+ up top
Forecast Summary:
Short Term (Days 1 – 4):
The current infrared satellite image (below) this afternoon shows a weather system moving into the PacNW and a warm front aligned north to south along the coast. A large blob of clouds and moisture is also seen moving from the central Pacific toward the West Coast and that area of cloudiness is associated with a moderate strength Atmospheric River (AR).
The warm front will move into Mammoth overnight and the system associated with the AR will bulls-eye the Tahoe region tomorrow with Mammoth being on the southern boundary. The jet stream and AR will then lift northward on Sunday (image below) and Mammoth will see a break from the weather until Tuesday.
The Quantitative Precipitation Forecast (QPF) from the guidance through Saturday varies a bit with the GFS model (image below) the driest at around 0.75” liquid. The ECM model (two images below) has around 1.25” while the National Blend of Models (NBM) is the wettest at around 1.75” (three images below).
The forecast leans toward the wetter guidance with well over an inch of liquid expected that would normally add up to more than a foot. However, this will be a warm storm and snow levels will start out tonight around 7-7500 feet, but should rise during the morning tomorrow and be in the 8500-9000+ foot range by late PM and evening.
There could be around 6”+ by Saturday opening bell before it gets warm and sloppy by the afternoon with most of the snow expected to fall by midday/early PM before it turns into a rain/snow mix probably up to the top of Ch. 4. Thus, there could be some good turns first thing in the morning from the overnight snowfall.
After a dry day on Sunday and Monday, the system will finally reload and shift southward through mid-week. The ECM model deepens and digs the trough southward Tuesday and Wednesday (images below) including a strong southwest jet into the Sierra. That will push what is left of the AR into the central and southern Sierra Tuesday and into Wednesday for a period of heavy snowfall/blizzard conditions for Mammoth.
The QPF from the guidance is generally quite wet with the ECM model (image below) showing around 4” liquid for the second part of the event. The GFS (two images below) is even wetter and has over 6” liquid, primarily because it is slower with the southward movement of the front.
Forecast follows a slightly wetter ECM solution with over 4” liquid expected. Snow levels will mostly be in the 7000 foot range for most of the event and snowfall ratios in the 8”:1” range. It will be Sierra cement base type snowfall and not dry powder except for possibly at the end of the snowfall Wednesday morning when snow levels get down to near 4000 feet. Nonetheless, probably three feet of new snow at Main and four feet up top.
Long Range (Days 5+):
The longer-range guidance continues to show an active storm track into central and northern CA through the end of next week. That could be followed by additional chances through mid-month or longer as the guidance continues to favor the West Coast with storminess.
The ECM model finally moves the longwave trough inland next Friday (image below) for another round of snowfall in Mammoth. This lines up well with the GFS ensemble (two images below). If this solution verifies, it would be colder and drier snowfall versus the Tuesday storm, but not super light overall. Right now, it looks like another six inches of snowfall is possible.
Overall, the guidance is showing a lot of precipitation for central and northern CA over the next week (images below) including some needed rain in SoCal too. Mammoth could easily get 7”+ liquid over the next week that would really help with coverage up top with five plus feet of snowfall.
After a break next weekend, the GFS ensemble is favoring the longwave trough to reform along the West Coast early the next week (image below) before retrograding a bit farther westward by the end of the week (two images below). That solution would be favorable for colder type storms to move southward from the Gulf of Alaska for more powder days.
The GFS ensemble is showing above normal precipitation for the 11-15 day period (image below) and the ECM EPS is also showing above normal precipitation (two images below). Further, the latest ECM EPS 45-day forecast has either average or slightly above normal precipitation ongoing through February and into the middle of March. Let the good times keep on rolling. WG
