Powder Forecast — Tuesday March 14th, 2017
Ted Schlaepfer CCM —- Mammoth Mountain WeatherGuy
Dry weather continues through Friday with lots of clouds over the weekend and a chance for flurries, but no significant snowfall. Snowfall probably develops by late Monday next week with a minor storm cycle of two or three storms for the rest of the week and following weekend. Longer range climate models say colder type storms could then continue at times into mid-April.
Next update Friday 3/17
Snowfall forecast are for the Sesame snow course (Main Lodge)
**Snowfall forecast confidence ranges from very low (1) to very high (5)
Wed 3/15 = 0”
Thu 3/16 = 0”
Fri 3/17 = 0”
Sat 3/18 = 0”
Sun 3/19 = 0”
Mon 3/20 = 0 – 3”
Tue 3/21 = 3 – 6”
Wed – Fri 3/22 – 24 = 12 – 24”
March Snowfall = 10.5”
March Forecast = 40 – 55”
Seasonal Snowfall = 520.5”
Seasonal Forecast = 600 – 625”
Detailed 5-day Snowfall Forecast:
Wed 3/15 through Sat 3/18 — No snowfall expected all days.
A high pressure ridge will weaken Wednesday and move eastward in response to a trough of low pressure moving into the PacNW (image below). A weak front will brush NorCal and there will be an increase in cloudiness in Mammoth by the afternoon for flat light conditions, but no snowfall to go with the slightly colder temps by around 5 degrees and an increase in west winds. It should stay spring conditions on the lower part of the mountain with firmer conditions up top.
High pressure rebuilds weakly for the rest of the week for fair conditions with increasing clouds by Friday. Changes in the weather pattern start over the weekend with the models advertising a trough of low pressure developing off the CA coast by Sunday (image below). That means lowering freezing levels to below 9K Saturday and 8K Sunday, breezy southwest winds, and lots of clouds for flat light conditions. There could be flurries on both Saturday and Sunday afternoons, but no significant snowfall is expected through Sunday.
Changes in the weather pattern continue early over the following week which will probably end the normal winter dry spell that will have lasted about two weeks. Interesting that it might end on the first official day of spring.
The ECM model (image below) is similar to the GFS and moves the first upper level low pressure system into CA on Monday night and next Tuesday for a period of moderate snowfall. Models are slow to move the upper low eastward Wednesday which would keep the snowfall going into early Thursday.
The GFS model (image below) has over an inch of QPF for about a foot of snow at Main Tuesday while the ECM have over an inch and a half. The ECM brings in another inch of liquid precipitation Wednesday while the GFS is slightly less. The details will change, but it looks good for a return to powder conditions around next Tuesday with a couple rider of storm days possible around the middle part of next week.
Models are in good agreement that it won’t be a one shot storm with a minor storm cycle developing next week. There could be the passage of another upper level low pressure system toward the end of next week in what appears to be split jet stream flow with more energy moving into the southern branch. Both the ECM (image below) and GFS have a decent storm poised for that next weekend.
The GFS ensembles are favoring this split flow pattern to continue through that weekend and into the next week. The difference appears to be a more northwest oriented jet stream in the split flow (image below) which could bring a colder type storm into Mammoth. The question with these storms always is how much moisture will they have to produce snowfall as they are often cold but dry.
The longer range GFS ensemble (image below) keeps this pattern going to almost the end of the month for a continued chance for weak storms or maybe cut-offs. The ECM ensemble is similar, although I suspect there will be a dry period of a few days after the potential weekend storm.
The CFS climate model has backed off on the dryness (image below) for early April and the ECM model is similar keeping a trough along the interior West and a ridge parked off the coast which would allow colder type storms to move into CA and/or slider type storms depending upon the exact trajectory. How much over ocean transport will be the key to snowfall potential with this type of pattern. Nonetheless of any snowfall, it would keep temps seasonably cool for slower snowpack melt.
Overall, looks like powder days return next week and last through the following weekend with higher than normal level of confidence for occurrence of such a long range forecast. WG