Powder Forecast – Friday March 24th, 2023

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 3/25 = 0”
Sun 3/26 = 0 – 1”
Mon 3/27 = 0”
Tue 3/28 = 0 – 1”
Wed 3/29 = 18 – 23” (H20 = 1.65” – 2.00”)**3
Thu 3/30 = 2 – 6”
Fri 3/31 = 0”
Sat – Mon 4/1 – 4/3 = 0”

March Snowfall = 157”
March Forecast = 175 – 185”

Detailed 4-day Snowfall Forecast

Sat 3/25 – Chance for late afternoon/evening snow showers, otherwise no snowfall expected.

Sun 3/26 and Mon 3/27 –No snowfall expected both days other than a chance for a flurry Sunday PM/evening.

Tue 3/21 –Snowfall develops during the morning and becomes heavy during the afternoon.  Light to moderate snowfall continues overnight.  Strong winds during the day.  Accumulations 18 – 23” by Wednesday AM, 24”+ up top

Forecast Summary:

Short Term (Days 1 – 4):

  The current infrared satellite image (below) this afternoon a cold front draped across Central and Northern California with the area of low pressure that produced a few inches of snowfall yesterday well east of the Sierra. 

   A trailing short-wave off the Oregon coast will move through the Sierra tomorrow afternoon and night with the upper-low into the Great Basin by Sunday morning (image below). Snow showers will probably increase tomorrow afternoon and evening leading to maybe an inch accumulation. Sunday should be mostly dry except for a chance for an afternoon flurry.

   After a dry day Monday, models are in agreement that another impactful storm will move into Mammoth on Tuesday as a deep upper trough develops off the coast (image below). The strong front will move through Tuesday afternoon and night with the deep upper-low centered over CA by early Wednesday (two images below).

  Snow should start on Tuesday morning and become heavy during the afternoon and evening as the front moves through. Snow intensity will then taper off overnight with light to moderate snowfall expected during the day Wednesday before ending Wednesday night. The GFS is a bit farther south/east with the upper lows position Wednesday and has a bit more snowfall during the day versus the ECMWF.

  Snow levels will start out around 5000 feet before falling to near 3000 feet by early Wednesday. So it won’t be a Sierra cement type snow and will be colder/drier/fluffier in nature versus typical Sierra snow types.  Ratios should be in the 10-12″:1″

   The GFS is showing about 2” liquid for the storm (image below) while the ECMWF is showing slightly less (two images below).  Snow amounts could be around 2 feet at Main if the wetter solutions verify and snow ratios end up higher, otherwise another 18”+ at Main is probably the best bet with close to 2 feet up top.

Long Range (Days 5+)

  The longer-range guidance is showing a slow transition into spring over the first part of April with potential storm getting weaker as the jet stream loses its punch as the sun grows stronger.  With a new record in place at 62” SWE for the E. Sierra watershed and over 90” at Mammoth pass (image below), any more at this point would just be icing on the cake.

  The upper low is going to slowly sag southward Thursday and Friday into SoCal and Mammoth will be mostly dry other than a chance for an afternoon flurry Thursday. Temps will stay winter-like cold on Thursday before warming up Friday. Conditions on the mountain should be epic, especially Thursday.

   High pressure will build into the state on Saturday (image below) and should hold through early the next week for fair weather and more seasonable temperatures.

  The longer-range fantasy guidance is not too different with both the GFS ensemble (image below) and ECM EPS (two images below) showing a longwave trough redeveloping along the West Coast around mid to late week. The only real difference is that the ECM is a bit deeper/faster with the trough and more supportive of a storm that could produce powder conditions.

   The ECM EPS keeps a weak trough in place through the end of the period (image below) and while it may not support a storm, strong high pressure or a quick warm-up is also not favored with winter-like conditions probably continuing across the upper half of the mountain.

  Mostly dry, but seasonably cool weather is also what the latest EPS 45-day forecast is showing for the super extended period with temps staying below normal through early April (image below) before warming up to near normal by mid-April (two images below).  A slow transition to spring.  WG