Tuesday May 24th, 2016
Ted Schlaepfer CCM —- Mammoth Mountain WeatherGuy
Snow showers are expected to develop late this afternoon and into the evening including a chance for thunderstorm. There is a chance that flurries could linger overnight before snow showers increase again during the day tomorrow with a couple inches of accumulation possible by Wednesday evening when the showers end. Other than a chance for a rain shower or thunderstorm each day after the lifts close through the Memorial Day weekend, generally fair weather with typical spring conditions is expected for the rest of the season with warmer weather possible in early June.
Last update of the season. Next update November 2016
Snowfall forecasts are for the Sesame snow course (Main Lodge) as reported in the AM snow report from MMSA (previous 24 hours of snowfall)
Sesame Snow Course
Wed 5/25 = ~1” (H2O = 0.05″ – 0.15″)
Thu 5/26 = 2 – 3” (H2O = 0.25″ – 0.40″)
Fri 5/27 = 0”
Sat 5/28 = 0”
Sun 5/29 = 0”
Mon 5/30 = 0”
Tue 5/31 = 0”
Wed – Fri 6/1 – 3 = 0”
May Snowfall = 4”
May Forecast = ~7”
2015-16 season total = ~360”
Winter-like conditions increase again today and Wednesday as an upper level low pressure system (image below) moves south of Mammoth and through SoCal on Wednesday. Snow showers increase this afternoon and into the evening above 8000 feet before tapering off overnight, although there is a chance for continued flurries into Wednesday morning. Due to the unorganized nature of the precipitation, no meaningful accumulation is expected today.
Models are suggesting that wrap-around flow in the counterclockwise circulation of the broad trough of low pressure will increase Wednesday with Mammoth actually being on the preferred up-slope side of the easterly flow this time.
The ECM and Canadian models are showing around a quarter to third of an inch of liquid for a few inches of snow while the GFS model is much more bullish on more significant precipitation with over an inch along the Sierra crest (image below) and up to three quarter of an inch in Mammoth. The GFS model is likely overdone as there doesn’t appear to be enough organized dynamics for such hefty amounts with the Canadian and ECM the preferred models.
That means there could be a couple inches of snowfall (and a bit more up top) with rising snow levels Wednesday to near 8500-9000 feet by the afternoon and rain likely in town. It will be a wet type of snowfall and there could be enough for fun turns by the time the lifts close Wednesday at 2 PM, but powder conditions are unlikely.
The broad trough of low pressure then moves eastward Thursday for a return to mostly dry weather and spring conditions by Friday. There will still be a chance for late afternoon showers or a thunderstorm after the lifts close through the Memorial Day weekend with any precipitation falling as rain. Overall, with a weak trough along the interior West (image below), the weather over the Holiday weekend will be very typical for late May.
The models are suggesting that warmer weather is possible by the end of next week with decreasing late afternoon showers and thunderstorms for the Sierra starting around Tuesday next week. The GFS model (image below) has now come on board with the ECM model showing a typical early June pattern of a weak jet stream into BC with ridging extending southward into CA.
If this pattern were to verify, then a period of warmer than normal weather will develop by the end of next week and into the following weekend. That would mean more sunshine and earlier softening of the snow during the morning, and of course, earlier slush by afternoon.
The longer range climate models (image below) are showing this pattern lasting into the second week of June or longer, possibly to near closing day which is currently projected for June 12th. Overall, after tomorrow, no more snowfall is expected for the 2015-16 season with typical or warmer than normal weather favored through mid-June.
Quickly looking at the big picture, the El Nino did not produce as much snowfall as forecast (360” actual versus 435” forecast) as the jet stream did not stay consistently southward as expected during the winter with only an occasional glance into SoCal. That resulted in most of the precipitation staying in NorCal and into the PacNW.
La Nina conditions are favored (image below) for next winter (~60% chance) which does not have a strong precipitation signal in central and northern CA, although snowfall often can be above normal farther north in the Sierra due to colder storm systems (less rain for Tahoe). However, La Nina does have a dry bias for SoCal and with Mammoth generally in the middle of CA, the early guess would be for average or slightly below normal snowfall next season (average is 350”), although confidence is low due to the large spread of outcomes in the past analog years.
Best case scenario would be a repeat of the moderate La Nina from just before the drought started in 2010-11 when there was 662” of snowfall that included powder storms through May. Enjoy the offseason. WG