Mammoth Mountain Weather Forecast & Discussion

Powder Forecast – Friday, February 28^th, 2025

This Section Updates Every Tuesday & Friday by 5 PM

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. Sesame Snow Course **Snowfall forecast confidence ranges from very low (1) to very high (5) Sat 3/1 = 0” Sun 3/2 = 0 – 1” Mon 3/3 = 4 – 6” (H20 = 0.35” – 0.65”)**2 Tue 3/4 = 0 – 1” Wed 3/5 = 1 – 2” Thu 3/6 = 4 – 6” Fri 3/7  = 0” Sat – Mon 3/8 – 3/10 = 6 – 15” February Snowfall = 74” February Forecast = 74” Detailed 4-day Snowfall Forecast: Sat 3/1 – Dry during the day and most of the night, with light snowfall expected to increase around dawn. Accumulations 0 – 1”. Sun 3/2 – Light to moderate snowfall during the morning, tapering to snow showers during the afternoon and overnight.  Accumulations 4 – 6” by Monday AM at Main, 6”+ up top. Mon 3/3 – Snow showers end during the morning, with just a chance for flurries the rest of the day. Accumulations 0 – 1”. Tue 3/4 – Dry during the day and most of the night, with light snowfall expected to increase late at night. Accumulations 1 – 2” by Wednesday AM. Forecast Summary: Short Term (Days 1 – 4):

  The current infrared satellite image (below) shows a weak cut-off low-pressure system positioned off the SoCal coast and some high clouds spilling into the southern half of the CA. That low-pressure system will move into northern Baja on Saturday and too far southward for shower activity.

  A trailing weather system (image above—well off the coast) will quickly move into NorCal by early Sunday (image below), and the cold front will move into Mammoth during the morning hours.  Light to moderate snowfall should start around dawn and continue until about midday (riders of the storm) before changing to snow showers for the rest of the day and night. Snow showers should end on Monday morning with dry weather and expected through Tuesday.

  The system’s model QPF varies slightly, with the ECM model (image below) forecasting the driest at around a third of an inch and the other models (images below) forecasting around 0.50” to 0.65” liquid. The forecast follows a blend of the guidance and favors about half an inch of liquid or 4-6” of snowfall, enough for powder conditions.

Long Range (Days 5+):

   The longer-range guidance still says that the weather pattern will slowly become more favorable over the first couple of weeks of March and into mid-month. How favorable is still undetermined, but the guidance is starting to favor better chances for more significant snowfall during the second week of March and heading into mid-month.

   The models move another trough into CA around mid-week and struggle to determine its strength, moisture tap, and speed.  The latest ECM run (image below) favors a stretched-out trough that deepens after landfall.  That solution matches well with the GFS ensemble, but the ECM ensemble holds the trough together upon landfall for a better chance for larger amounts, as reflected in the QPF (image below), which has almost an inch of liquid.  The current forecast takes a middle ground and favors about 4-6” and enough for powder conditions.

  The longer-range guidance suggests a better chance for significant snowfall in the 10-14-day period. The GFS ensemble (image below) and the ECM EPS develop a deep trough off the CA and West Coast on Sunday and/or Monday that week. Both show a decently strong southwest jet stream into the Sierra for good orographic lift and spill-over into the eastern side.

  The GFS ensemble keeps the longwave trough across the middle and western US through the following week (image below), keeping CA in mostly northwest jet stream flow.  That would allow weak/moderate systems to drop into CA from the Gulf of Alaska.  The ECM ensemble has the trough farther westward during the middle/latter part of that week, which would allow any storms moving into CA to have a better over-water trajectory before landfall and potentially larger precipitation amounts.

   That is illustrated in the QPF anomaly charts for that week, with the ECM EPS (image below) showing above-normal precipitation while the GFS ensemble (two images below) is showing slightly above.  The ECM EPS is suggesting two or more inches of liquid (three images below) that could add up to possibly two feet or more during the week.  Hopefully, the EPS pattern will pan out.

  For the second half of March, the fantasy range solutions favor a long-wave trough of unknown strength/depth to remain mostly along the West Coast until possibly the end of the month.  The GFS and CFS models are more bullish on this solution versus the ECM, with the last monthly forecast by the CFS model (image below) showing slightly above normal precipitation next month for Mammoth.  March average is around 60”, which suggests a 70-80” month.  I’ll take it.  WG