Powder Forecast – Friday, April 12th, 2024

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 4/13 = 0 – 1” (H20 = 0.05” – 0.10)**2
Sun 4/14 = 5 – 7” (H20 = 0.50” – 0.70)**3
Mon 4/15 = 1 – 2” (H20 = 0.10” – 0.15)**3
Tue 4/16 = 0”
Wed 4/17 = 0”
Thu 4/18 = 0”
Fri 4/19 = 0”
Sat – Mon 4/20 – 4/22 = 0 – 1”

April Snowfall: 28”
April Forecast = 35 – 45”

Detailed 4-day Snowfall Forecast

Sat 4/13 – Snowfall likely develops by the early afternoon and may become briefly heavy during the evening hours before tapering off overnight. Accumulations 5 – 7” by Sunday AM at Main, up to 9” up top.

Sun 4/14—Light snowfall redevelops during the day and into the evening before ending overnight. Accumulations are 1 – 2” by Monday morning, up to 3” up top.

Mon 4/15 and Tue 4/16 – No snowfall expected on both days.

Forecast Summary:

Short Term (Days 1 – 4):

   The current infrared satellite image (below) today shows a weather system off the CA coast that will produce a period of snowfall tomorrow and a high-pressure ridge now edging eastward out of the state.  As the system approaches this afternoon, there is a chance for an afternoon shower or thunderstorm with snow levels around 9-10000 feet.

  The upper-level trough will move onto the coast early tomorrow (image below) while cutting off from the jet stream.  The mid-level flow will be more southerly versus southwest; thus, spill-over onto the eastern side of the Sierra won’t be as efficient, nor will the flow up the San Joaquin River drainage basin.  Most of the snowfall will occur with the frontal passage during the late afternoon and evening hours tomorrow with snow levels around 4-5000 feet.

  Model QPF is generally divided into two camps. The GFS (image below) and the Canadian models (two images below) show the least liquid precipitation, with only about a third of an inch. That would result in about three inches at Main.

  The ECM model (image below) and the NBM (two images below) are both showing about twice the amounts as the other models and that would equate to around 6” at Main. The variations are likely due to the placement of the upper low with every mile making a difference with how far east the front progresses.

  The ECM model then moves the cut-off eastward through the state on Sunday (image below) and then eastward into Nevada/Utah on Monday (two images below), when it becomes an open wave again.

  The guidance suggests that light snowfall will redevelop on Sunday during the day during its passage before ending Sunday night.  This time, the models are in agreement that amounts will remain light and mostly around a tenth of an inch (images below) or only an inch or two more of snowfall.  While not heavy snowfall, the pond skimmers may be a bit chilly under the unseasonably cool temperatures.

  The forecast follows the ECM EPS, which has about 0.90” liquid (image below) for the event, about 6-8” with the main front Saturday, and then a couple more inches Sunday for a total of almost 7-9” for the weekend. As you will see below, there are no guarantees that there will be additional powder days as we move toward the latter part of April and May. Get up here now if you need another one.


Long Range (Days 5+):

   The longer-range guidance still suggests a chance for a spring storm during the second half of the month and through most of May as well. However, the exact dates of when that may occur are not known after this weekend. There have been no changes from the last post.

  The guidance has shifted warm and dry for next week, with a high-pressure ridge holding through at least Thursday (image below).  That means spring weather and conditions should return to the entire mountain by mid-week.  The ridge may weaken a bit over the following weekend, but not much change in the weather is expected, with continued dry weather for Mammoth.

  The next slight chance for snowfall will likely not be until around the end of the following week.  The GFS ensemble is favoring the development of trough along the West Coast (images below), although it currently has the jet stream too far northward for significant precipitation.  The ECM EPS agrees and is only showing very light liquid amounts (three images below).

  A wild guess of when the next chance may happen would be around the first week of May.  May powder days are infrequent, but do happen, generally through mid-May. But I would not get your hopes up, and I’d count on slush turns instead.  WG