Powder Forecast –Tuesday April 15th, 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)
Wed 4/16 = 0”
Thu 4/17 = 0 – 1”
Fri 4/18 = 0 – 1”
Sat 4/19 = 0”
Sun 4/20 = 0”
Mon 4/21 = 0”
Tue 4/22 = 0”
Wed – Fri 4/23 – 4/25 = 0”
April Snowfall = 17”
April Forecast = 20 – 25”
Detailed 4-day Snowfall Forecast:
Wed 4/16 – Dry during the morning/early afternoon, then scattered showers and a chance for thunderstorms during the late afternoon/evening, snow levels around 9000-9500 feet. Up to an inch accumulation.
Thu 4/17 – Dry during the morning/early afternoon, then scattered showers and a chance for thunderstorms during the late afternoon/evening, snow levels around 9000-9500 feet. Up to an inch accumulation.
Fri 4/18 and Sat 4/19 – No snowfall expected both days.
Forecast Summary:
Short Term (Days 1 – 4):
The current infrared satellite image (below) this afternoon shows some cloudiness spreading over California from an area of low pressure positioned off the SoCal coast. It will move toward the coast through Wednesday and will help initiate afternoon showers and thunderstorms over the Sierra with snow levels around 9000-9500 feet.
It will move into SoCal early Thursday (image below) and slightly farther southward versus the ECM model projection from the last post. It will also now not merge with a low dropping southward from Canada until Friday and generally south/east of Mammoth.
The result is a lesser chance for accumulating snowfall with the best chance for anything meaningful being a perfectly positioned strong thunderstorm over the mountain. QPF from the guidance is still mixed with the GFS (image below) and NBM (two images below) showing around half an inch liquid for this week. But the ECM (three images below) and the Canadian (four images below) are only showing very light liquid amounts around a tenth of an inch or so.
Forecast leans toward the ECM with shower/thunderstorms on both Wednesday and Thursday afternoons (and snow levels around 9000-9500 feet), but not favoring any significant accumulation with maybe an inch each day at Main. However, a couple/few inches each day can not be ruled out for the upper part of the mountain, especially if there are heavier showers.
Weak high pressure rebuilds into the state on Saturday (image below) for fair and slightly warmer weather this weekend for the Canyon/Eagle closing. The weather for the pond skim should be fair and just a little breezy.
Long Range (Days 5+):
The longer-range guidance is generally dry through next week with just a slight chance for light snowfall over the last weekend of the month. Typical spring weather is then favored for the last part of April and into May, although there is always a chance for a surprise storm, with models still hinting at something for the end of the month or early May.
The guidance is suggesting that generally fair weather will return next week with a very weak longwave trough just east of CA (image below) and a ridge in the eastern Pacific. Under the weak northwest flow, temperatures should be seasonable and spring-like.
The GFS ensemble shifts the weak ridge of CA during the 11-15 day time frame (image below) for continued fair weather and slightly warmer temperatures. The ECM EPS on the other hand, moves a short-wave trough into CA over the last weekend of the month (two images below) for a chance for snowfall. That model is currently only showing light amounts, but it is too far out in time for an accurate forecast.
The rest of April and early May is favored to see typical spring weather. While most days will be sunny and warm/mild, typical spring weather also means a chance for a surprise storm. The ECM EPS brings another short-wave trough into CA at the end of month for another chance and the ECM EPS 45-day forecast has over an inch liquid for the end of month and first week of May. Late season storms happen. WG
