Powder Forecast – Friday, November 9th, 2018
Ted Schlaepfer CCM —- Mammoth Mountain WeatherGuy
Sunny weather is expected through the weekend and most of next week as well. Temperatures will get a little colder Sunday and into Monday before warming up into the middle/end of next week. First chance for seasonal snowfall looks to be around Sunday/Monday the 18th/19th with better chances over the following week and rest of month.
Next update Tuesday 11/13
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 11/10 = 0”
Sun 11/11 = 0”
Mon 11/12 = 0”
Tue 11/13 = 0”
Wed 11/14 = 0”
Thu 11/15 = 0”
Fri – Mon 11/16 – 19 = 0 – 6”
November Snowfall = 0”
November Forecast = 20 – 30”
Detailed 5-day Snowfall Forecast:
Sat 11/10 through Tue 11/13 — No snowfall expected all days.
Sunny weather is expected through the weekend and into next week with seasonably cool temperatures. An upper-level ridge will remain off the West Coast and block all storms to the north before they move southward through the Great Basin as inside slider type systems.
The next one moves east of the Sierra Sunday (image below) and will re-enforce the colder air already in place from the one that moved through Thursday. This pattern should last through early next week. That means snowmaking will be pretty good, especially at night and during the morning hours.
The longer range guidance is favoring a pattern flip to occur over the latter part of next week and into the following weekend. The ECM model (image below) flattens the upper-level ridge off the coast while moving it eastward over California end of next week.
That means continued dry weather and with the jet stream flow now out of the west, expect warmer temperatures and less ideal snowmaking conditions that might be confined to night-time hours only. This pattern should continue into the following weekend.
The fantasy period of the guidance is then suggesting a more favorable pattern for snowfall may develop as early as late that weekend or probably more likely over Thanksgiving week. The current weather pattern has basically been in place for the last 30 days and has to give at some point.
The GFS model is the most bullish about a quicker turn-around with the pattern moving a decent strength short wave quickly southward and through California around Sunday the 18th (image below). It currently projects the short wave to be strong enough to generate over 0.50” liquid precipitation (two images below) and up to 6” of snowfall.
However, the latest ECM run (image below) shows the short wave splitting before moving onto the coast and moving southward into Baja for no precipitation. The Canadian (two images below) is also different showing a much weaker short wave moving through NorCal and also no snowfall for Mammoth.
A few of the ECM ensembles are similar to the GFS and the current forecast does including a chance for up to 6”, but confidence is generally low with any solution that far out in time.
The latest ECM (image below) does appear to be moving a stronger short wave southward into the West Coast early over the following week and the GFS also moves another one southward into CA by mid-week.
This trend generally agrees with the climate models that are favoring a beneficial pattern change for the last part of November and through the first half of December or longer. The CFS basically has a snowy pattern starting around Thanksgiving and lasting to near Christmas (images below). The latest ECM model is similar, although it breaks the pattern a bit earlier. Nonetheless, it could be 2-3 weeks of persistent storminess according to the long term models that are not particularly accurate most of the time.
The 2018-19 ski season looks to feature a moderate El Nino in the tropical Pacific that won’t peak in strength until mid-winter and is a bit later than the typical El Nino that usually peaks around Christmas.
Also, this El Nino won’t be a typical eastern Pacific based one with the warmest anomalies farther westward over the Central Pacific including a warm pool in the far western Pacific that is usually cooler than normal during El Ninos.
These Modoki type events have been both wet and dry for CA with the moderate strength events having been more wet than dry while the weak events have been opposite. Still, lots of variability within each threshold.
Other factors to consider for the winter forecast is the QBO that is a measure of the stratospheric winds over the equator and can influence the teleconnection pattern in the Northern Hemisphere during winter. Last winter, it was in the negative phase and this winter it is transitioning into the positive phase.
The negative phase with the QBO is associated with a better chance of persistent high latitude blocking while the positive phase has been associated with lesser chances. Last year, high latitude blocking was responsible for the basically dry mid-winter as the block set up in the wrong spot and CA was under a persistent ridge with the favorable troughing to the east.
The other factor to consider during winter is tropical forcing from the MJO. Unfortunately, there is no way to know how it will behave this winter beyond a few weeks and will be the wildcard for how much snowfall plays out this winter.
Overall, the moderate El Nino combined with a lesser chance for persistent high latitude blocking will probably translate into a decent or good winter for Mammoth. The snowfall outlook is calling for 365” of snow with a 50% chance of snowfall between 300-400” and 25% chance for less/more than those amounts (image below).