Mammoth Mountain Weather Forecast—November 3rd, 2017

Powder Forecast — Friday November 3rd, 2017

Ted Schlaepfer CCM  —- Mammoth Mountain WeatherGuy

Forecast Summary:

Light snow should start early Saturday and continue at times into Sunday morning with dry weather probably returning by Sunday night with a few inches of accumulation.  Dry weather should then continue through Wednesday with decent snowmaking conditions.  There will be a chance for snow by Thursday night and next Friday followed by another chance late over the weekend and early over the following week.   Longer range models suggest snow chances will continue every few days through mid-November, but no major storm pattern for Mammoth yet.

Next update Tuesday 11/7

Snowfall forecast are for the Sesame snow course (Main Lodge)

**Snowfall forecast confidence ranges from very low (1) to very high (5)

Sat 11/4 = 0 – 1”
Sun 11/5 = 1 – 3” (H20 = 0.15” – 0.25”) **4
Mon 11/6 = ~1”
Tue 11/7 = 0”
Wed 11/8 = 0”
Thu 11/9 = 0 – 2”
Fri 11/10 = 2 – 6”
Sat – Mon 11/11 – 13 = 0 – 3”

November Snowfall = 0”
November Forecast = 30 – 40”

Detailed 5-day Snowfall Forecast:

Sat 11/4 —Light snow likely develops during the morning and peaks evening before tapering off into Sunday AM.   Accumulations 1 – 3” by Sunday, ~3” up top.

Sun 11/5 —Light snow likely ends during the morning, maybe an inch accumulation.

Mon and   Tue 11/6-7 — No snowfall expected both days.

Forecast Discussion:

Short Term:   

The longer range models teased us with a chance for a larger storm to start out the season, but alas, it is not to be, with just a weak system moving through Mammoth and most of the precipitation staying well north of Mammoth into the northern Sierra. The latest ECM model (image below) barely digs the upper trough southward enough now for any decent snowfall and the GFS model is similar.

Both models are showing only light amounts of QPF (Quantitative Precipitation Forecast) of about a third of an inch of liquid (image below) that would result in only a few inches.  The GFS has most of the snow falling Saturday evening while the ECM has it falling overnight into Sunday.

The snowfall should end during the morning hours Sunday with the upper trough moving eastward by early Monday per the ECM model (image below) and weak ridging moving into the area through mid-week for dry weather.   Colder and drier air should aid in snowmaking with freezing levels remaining below 9000 feet through Tuesday.

Long Range:

   The longer range models are suggesting that another trough of low pressure will move into California around opening day next week.   This one is coming from a more westerly direction (image below) after dropping southward around a stationary high pressure block in the Aleutian—farther westward that the upper trough expected to produce light snow this weekend.

The big question with this trough will be how far southward it digs before moving ashore and will it be far enough southward to be more than a brush job for Mammoth.  Right now, the models are mixed about that idea with the ECM model now currently the farthest south, but models have been trading solutions with almost every run.

Since we are still in the fall and the transition season, the numerical guidance really can’t be trusted more than a few days out.   Not a good time of the year to try to be the first forecaster to call out big storms in the extended time frame.  The models will improve as we head toward winter.

Best guess right now is that Mammoth get a few inches to maybe six inches around next Thursday and Friday.  It is only early November and a bit early for low pressure systems to drop too far south.   Remember, Mammoth only received 12” of snow last November (while the N. Sierra had above normal rainfall), but ended up with over 600” snow. It’s early.

The longer range models are rather active with low pressure systems moving on the West Coast (image below).   The latest ECM model moves another one into CA around Monday the 12th.  Same question abounds with this trough as the previous one—will it dig far enough southward?  Right now it looks like another few inches, but nothing major.

The climate models are active with a trough along the West Coast and block in the Aleutians through mid-November or longer.  That will keep storm chances going through the 3rd week of November.   As we get farther into the season, these storms should begin to move farther southward.

I also like seeing that block developing in the Aleutians again, similar to last season.  If this was Dec/Jan/Feb, there would be a better chance to see enough jet energy to break underneath the block for an extended or possibly wet period containing ARs.   That is generally what is expected again this season, but just not to the extreme of the epic 2016-17 season. WG