Powder Forecast –Friday, November 16th, 2018
Ted Schlaepfer CCM —- Mammoth Mountain WeatherGuy
Mostly sunny weather is expected through the weekend with slightly colder temps Sunday and Monday. The dry weather should last into early next week before snowfall is favored by the middle and latter part of next week. Another chance for snowfall is possible over the latter part of the Holiday weekend before fair weather may return over the following week. Longer range guidance is now favoring dry weather first part of December before storms may return by the second week of the month.
Next update Tuesday 11/20
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)
Sat 11/17 = 0”
Sun 11/18 = 0”
Mon 11/19 = 0”
Tue 11/20 = 0”
Wed 11/21 = 0 – 1” **4
Thu 11/22 = 9 – 15” **2
Fri 11/23 = 3 – 6” **2
Sat – Mon 11/24 – 26 = 6 – 15”
November Snowfall = 0”
November Forecast = 20 – 30”
Detailed 5-day Snowfall Forecast:
Sat 11/17 through Tue 11/20 — No snowfall expected all days.
Mostly sunny weather is expected through the weekend and into Monday next week with slightly colder temperatures by Sunday/Monday along with a slight increase in northeast winds. ECM model (image below) moves a weak slider type shortwave southward through the Great Basin Saturday night, otherwise, high pressure will remain off the coast and block any storms from moving ashore.
Overall, snowmaking will get a little better Sunday and Monday with the slightly colder temps. Other than possibly some increasing clouds Tuesday, not much change in the weather is expected through early next week.
It looks like the super long range guidance that was favoring snowfall around Thanksgiving as long as a few weeks ago may come to fruition next week. Medium range guidance is now showing a decent trough of low pressure moving southward to just off the California coast by early next Wednesday (ECM model below).
The ECM and Canadian models are the deepest and farthest south with the trough while the GFS is weaker and farther northward. As a matter of fact, the 12Z run of the GFS doesn’t bring any snowfall southward into Mammoth with the low-pressure system staying too far northward. Conversely, the 12Z run of the ECM has over 1.5” liquid with the passage of the trough that would equate to more than a foot at Main. The Canadian is showing only a tad less than the ECM model.
The current forecast follows the ECM ensemble mean that is favoring just over an inch of liquid and around a foot of snowfall for Main for Thanksgiving. It is still a bit too far out to believe any one of the runs of the operational models, especially since there has been quite a bit of run to run variability. The first part of the pattern should be in full focus by the Tuesday update.
The models then develop another trough in the wake of the passage of the Turkey storm that would possibly bring more snow Friday and/or again Sunday. The latest ECM is now farther northward with this feature and keeps Mammoth mostly dry Friday (image below). It does move another wave southward Sunday (two images below) for some light/moderate snowfall into Monday. Not sure I believe this particular solution.
The reason being is that the GFS and Canadian both show a slower solution with the upper-level long wave trough remaining off the coast and farther southward through the weekend (image below). The Canadian is the most aggressive with a couple feet of snow while the GFS shows modest amounts. The 12Z GFS showed around 15” for Mammoth (two images below) for the total period with most of that falling over the latter part of the weekend.
The current thinking uses a blend of all the models for maybe another foot of snow. Still way too early to say there will be big snowfall over the Holiday weekend like the Canadian model suggests, but there is certainly a chance. Hopefully, these storms will come through and lay down a much-needed base so we can start having powder days.
The longer range guidance is now favoring the longwave trough to shift eastward over the last part of the month and possibly into early December. The GFS model (image below) and most of the ensembles are showing this pattern that would put Mammoth in a light northwest flow. That would mean dry weather and seasonable temperatures.
Not surprisingly, the CFS climate model has now backed off its wet forecast through mid-December and is now favoring average precipitation (images below). The ECM model also drifted slightly drier, but still shows a bit more potential snowfall than the CFS, particularly the second week of December. At least those models are not showing a strong dry signal, but overall, I would not put too much weight into those super long-range forecasts regardless. WG