Powder Forecast –Tuesday, February 19th, 2019
Ted Schlaepfer CCM —- Mammoth Mountain WeatherGuy
Mostly light snow showers develop Wednesday afternoon and continue into the evening before ending overnight.
Snow showers may redevelop Thursday afternoon and continue overnight with snowfall expected to end Friday morning.
Rest of Friday will be dry with dry weather expected Saturday as well. Next chance for snow will be early Sunday and into Sunday night.
Dry weather may return early next week with the next storm cycle not likely until March.
Overall, low-end powder conditions are possible Thursday and again Sunday/Monday. Next chance for deep powder could be around early March (March 2-5th).
Next update Friday 2/22 by 5PM
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 2/20 = 0”
Thu 2/21 = 2 – 4” (H2O = 0.15” – 0.30”)**2
Fri 2/22 = 1 – 3” (H2O = 0.05” – 0.15”)**2
Sat 2/23 = 0”
Sun 2/24 = 0 – 2”
Mon 2/25 = 2 – 5”
Tue 2/26 = 0”
Wed – Fri 2/27– 3/1 = 0 – 6”
February Snowfall = 190”
February Forecast = 195 – 200”
Detailed 4-day Snowfall Forecast:
Wed 2/20 —Snow showers develop during the afternoon and continue through the evening before ending overnight. Gusty winds resulting in wind holds. Accumulations 2 – 4” by Thursday AM, almost 6” up top
Thu 2/21 —Likely dry during the morning, then a chance for light snow showers by the late afternoon and continuing overnight. Breezy to gusty northeast winds. Accumulations 1 – 3” by Monday AM, 3”+ up top
Fri 2/22 and Sat 2/23—No snowfall expected both days. Breezy winds both days, but not too gusty.
Late morning satellite image (below) shows that weak high pressure has built into CA with the next upper-level low-pressure system to move into CA tomorrow is currently situated in the Pac NW.
That system is expected to increase the clouds late tonight and early tomorrow with snow showers likely starting during the afternoon.
The ECM model (image below) moves the upper-level low into central CA by early Thursday while cutting it off from the jet stream at the same time. It is another cold system, so snow levels will remain low and the cold air already in place re-enforced.
However, it is lacking in sufficient moisture to produce snowfall and is also taking a southward track into SoCal and any orographic enhancement over the Sierra will be minimal.
As a result, the model QPF is rather puny, especially versus recent storms that have resulted in the big February. GFS model (image below) is showing about a quarter inch liquid while the Canadian (two images below) is showing even less.
Latest ECM model has about a quarter inch or around 2-4 inches as the snow ratios should be high and in the 15-20”:1” range.
The system will exit eastward Thursday night and Friday and upslope moist easterly flow will likely produce more snowfall. It could begin Wednesday afternoon, but is more likely overnight and could result in a few more inches of fluffy snowfall by Thursday AM.
Temperatures should stay cold through Thursday and the few to maybe up to six inches total should be the dry, fluffy quality snowfall. Should be fun, but deep powder is not expected this time.
Friday will be dry and Saturday likely as well as weak high pressure builds into CA between storm systems.
The ECM model (image below) moves the next storm southward around Saturday night or Sunday next week with the bulk of the precipitation staying north of Mammoth and into Tahoe as the guidance says the trough will not dig too far southward.
Nonetheless, model guidance says another few inches or possibly up to six inches of snowfall may fall with this storm and should refresh the mountain over the weekend.
Again, not expecting deep powder with this storm at this time, but it is still many days out. It does not look to be as cold as the previous storm systems.
The longer range models are a bit mixed but are generally not showing any big storms for next week.
The ECM model (image below) actually moves an upper-level ridge over CA and shifts the deep trough eastward for a general pattern change back to drier weather and more seasonable temperatures.
It keeps any precipitation north of Mammoth with the big weather feature being a very strong ridge in Alaska.
The GFS, on the other hand, has the big ridge in Alaska slightly farther southward and keeps the associated weak trough south of it farther southward into NorCal as well.
It has the jet stream tapping some moisture and just far enough southward for some light precipitation in Mammoth around Wednesday next week. Some of the ECM ensembles show this solution, but next week is generally low confidence in any snowfall.
EMC model keeps the ridge over CA through the end of next week (image below) for fair, dry weather and seasonable temperatures after this long stretch of cold weather (except for the two days last week when it rained).
The ECM mean is split with most of the ensembles favoring the jet stream flow farther southward with less ridging than the operational model and only a handful showing the op solution.
That mostly means it could be a dirty ridge (high clouds) as the ensembles still favor the jet stream to stay north of Mammoth.
The longer range ensemble means then are becoming more bullish about a westerly under-cut of the ridge around the end of the month with a better chance it could happen in early March.
The GFS mean shows a very flat ridge becoming flatter into early March (images below) that would allow storm systems to move under that strong ridge in Alaska.
The ECM ensemble mean is actually more bullish about this solution than the GFS with more jet energy southward and under the ridge. It is showing a favorable multi-day pattern for snowstorms to move off the Pacific into CA.
These would not necessarily be cold storms like the storms over the past month, but more reminiscent of the storms in January and hopefully not too warm as the details are still a guessing game right now.
The latest CFS model (images below) also supports with a wet period with above normal precipitation starting end of February and lasting into the second week of March.
So it looks like a break from storms for about a week to ten days before the next storm cycle gets going again and hopefully powder days. WG