Powder Forecast – Tuesday, April 21st, 2026
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 4/22 = 14 – 16“ (H20 = 1.35” – 1.65)**3
Thu 4/23 = 0 – 1”
Fri 4/24 = 0”
Sat 4/25 = 0 – 1”
Sun 4/26 = 2 – 4”
Mon 4/27 = 1 – 2”
Tue 4/28 = 1 – 3”
Wed – Fri 4/29 – 5/1 = 3 – 9”
April Snowfall = 32”
April Forecast = 45 – 55”
Detailed 4-day Snowfall Forecast:
Wed 4/22 – Chance for lingering snow showers early morning, then partly/mostly cloudy with afternoon flurries. No meaningful accumulation expected.
Thu 4/23 and Fri 4/24 – No snowfall expected on either day, except for a chance of flurries late PM/evening Friday.
Sat 4/25 – Chance for snowfall to develop during the afternoon and continue into Saturday night. Accumulations 2 – 4” by Sunday AM
Forecast Summary:
Short Term (Days 1 – 4):
The current infrared satellite image (below) from this afternoon shows that a slow-moving cold front has moved into the Central and Eastern Sierra, with snowfall currently ongoing at Mammoth. It will continue to snow overnight as the front slowly moves eastward, and the snowfall should taper off early Wednesday with only flurries expected during the afternoon.
Amounts by the models at the time of the storm still vary a bit with the ECM model the lowest at just under an inch (image below), the GFS the middleman at around 1.35” (two images below), and the National Blend of Models the highest at about 2” liquid (three images below) or almost 20” of snowf l. The jet flow turns from southwest this afternoon to west/northwest overnight, which should decrease orographic effects and spill over into the eastern s e. The forecast leans toward a blend of the GFS/NBM, with over a foot at Main by Wednesday morning and a mountain-wide powder day.
Fair and dry weather returns Thursday and continues Friday, except for a chance of afternoon or evening flurries on Friday, out ahead of the next weather system for the week. The GFS model is the most aggressive, with a weak trough of low pressure (image below) positioned just off the Central Coast Saturday morning. The ECM model keeps the trough as an open wave and directs most of the weak wave energy farther southward into So al. The Canadian is farther northward, but not as deep as the GFS.
As a result, the QPF from the models varies, with the GFS being the wettest at just under an inch of liquid (image below) and the ECM model much drier at around a couple of tenths (two images below). The ECM EPS is slightly wet, at around 0.33 in (three images below). Forecast follows the ECM EP, S with a few inches of snowfall developing Saturday afternoon and continuing Saturday night,t for at least low-end powder on Sunday. Snow levels will start around 8000 feet before falling to 7000 feet by evening.
Long Range (Days 5+):
The longer-range guidance still looks very good for late April and early May and seems more representative of an early-spring pattern. There will be a continued chance of spring storms through the first week of May, or longer, and I can honestly say I am not sure when the last call for powder turns will happen, as the pattern may stay somewhat active during at least the first half of May.
A weak trough will probably remain over CA and the West through the weekend and into early next week, with a continued chance of snow showers, primarily during the afternoon and evening hours. A more organized, low-pressure system may then move toward the southern part of the state around Tuesday next week (image below), per the GFS below. It is the strongest model, with the latest ECM run showing a weaker solution (two images below), which is also better supported by the GFS ensemble mean (three images below).
The precipitation forecast by the models is uncertain, with the GFS showing more than twice the liquid amount compared to other models (imaelowel). The ECM (two images below) is the driest and the ECM EPS a bit wetter (three images bel w). Forecast leans toward the ECM EPS with a couple to a few inches forecast, hopefully the GFS model is right.
The fantasy range guidance indicates a similar weather pattern will persist during the first part of May, with a ridge over British Columbia and an undercutting jet stream into A. The latest ECM run moves a very deep trough for early May just off the CA coast on the 5th (image below), which would produce another round of snowfall, and be enough for powder.
Right now, the ECM EPS shows a much weaker trough in the CA image below; the ECM deterministic run solution is not believable just yet. The ECM EPS 45-day forecast keeps a weaker version of this weather pattern into mid-May, which will keep temperatures seasonable or seasonably cool, with a continued chance for precipitation at times. Powder in May is not unheard of at all, especially during the first half of the month. WG
