Powder Forecast – Friday January 24th, 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 1/25 = 0”
Sun 1/26 = 5 – 7” (H20 = 0.25” – 0.35”) **4
Mon 1/27 = 3 – 4” (H20 = 0.15” – 0.20”) **3
Tue 1/28 = 0 – 1”
Wed 1/29 = 0”
Thu 1/30 = 0”
Fri 1/31 = 0 – 1”
Sat – Mon 2/1 – 2/3 = 6 – 12”
January Snowfall = 1”
January Forecast = 8 – 15”
Detailed 4-day Snowfall Forecast:
Sat 1/25– Light snow showers develop during the morning and continue during the day with moderate snowfall developing overnight before tapering off near dawn. Getting colder during the day and night. Accumulations 5 – 7” at Main by Sunday AM and ~9” up top
Sun 1/26– Light snow showers at expected during the day and into the overnight hours. Cold. Accumulations 3 – 4” at Main by Monday AM and ~6” up top
Mon 1/27– Any lingering snow showers end during the morning or early afternoon, maybe an inch accumulation.
Tue 1/28 – No snowfall expected.
Forecast Summary:
Short Term (Days 1 – 4):
The current infrared satellite image (below) this afternoon shows a weather system moving southward through eastern Oregon and Idaho and a weak low just off the Central CA coast. The low across the interior will move southwestward overnight and tomorrow while deepening and merging with the low off the coast.
The model are forecasting the low to cut-off from the jet stream by early Sunday morning (image below) just southwest of the Bay Area and farther westward versus the solutions in the last post. That new position will allow the low to pull in needed moisture off the Pacific Ocean resulting in higher forecast snowfall amounts now (and also more rain in SoCal).
Light snowfall should start Saturday morning and continue during the day before increasing in intensity overnight Saturday before tapering off Sunday morning. Snow showers should then continue into Sunday overnight and into Monday morning. Dry weather returns Tuesday.
The system is cold and snow levels will start around 4000 feet Saturday before dropping to around 3000 feet early Sunday and then remain around 4000 feet into Monday. That means it will be cold/dry powder with ratios in the 15-20”:1” range. With winds are expected to be light when most of the snowfall occurs Saturday night, so the higher ratios are a good bet as strong winds can cause fracturing of the dendrites in the snowflake.
The ECM model (image below) and GFS (two images below) and in good agreement with around 0.50” total liquid for the event. The National Blend of Models is the wettest and has around 0.80” liquid (three images below). The forecast follows a slightly wetter GFS/ECM solution and enough for powder conditions by Sunday and Monday with around 9” at Main and over a foot up top for the event.
Long Range (Days 5+):
The longer-range guidance is now starting to offer some good news. How good of news has yet to be determined, but continued dry weather is not favored and there is a good chance that February will end up a good month with many powder days.
The upper-low associated with the snowfall this weekend will slowly meander through the Southwest into the middle part of next week (image below). High pressure will build north of the low and Mammoth will be in between the two. That means fair weather and seasonable temperatures and probably some easterly winds at times up top.
The guidance is then suggesting a short-wave trough will move through the state over the following weekend with the GFS bringing the first wave in on Saturday (image below) followed by another one Sunday. The ECM is slightly different with both waves moving through about 24 hours earlier. However, the ECM Artificial Intelligence forecast (two images below) has just one stronger wave moving through on Saturday with the latitude of the jet stream similar to the GFS.
The ECM AI is showing about 0.75” liquid (image below) that is only slightly less than the GFS model (two images below). If this pans out, then more powder conditions should be expected over that weekend. Best guess right now would be 6-12” of snow at Main with a good upside for more.
The long-range 11-15 day pattern is a good set-up for additional powder days featuring cold/dry powder type snowfall. The GFS ensemble has the longwave trough anchored across the West (image below) that would allow colder-type systems from the North to drop southward into CA. These storms would not have an Atmospheric River or big moisture taps, but would likely have low snow levels and could be rather dynamic under the right circumstances.
Both the ECM EPS (image below) and GFS ensemble (two images below) are showing average precipitation for the 11-15 day period. Average precipitation first week of February is over an inch liquid and enough for powder conditions.
The extended versions of those models keep storm chances ongoing through mid-February. And the latest CFS model is now showing above normal precipitation for next month (image below) and even suggests a good March too (two images below). Looks like winter is about to return. WG
