Powder Forecast – Tuesday May 21st, 2019
Ted Schlaepfer CCM —- Mammoth Mountain WeatherGuy
Light snow likely continues Wednesday before ending during the evening with a dry morning possible on Thursday. Snow showers may return by Thursday afternoon and into the evening followed by likely dry weather Friday. Next chance for light snow showers will be Saturday and into Sunday with a continued chance at times for light snow or rain showers through Memorial Day. Dry weather may return mid-week next week followed by a slight chance for precipitation end of next week. Overall, powder conditions are expected Wednesday and into early Thursday, then any snowfall rest of the week and weekend will likely not result in enough accumulation for powder conditions, although conditions will stay winter-like for the upper part of the hill. Spring likely returns next week.
Last update of the season
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)
Wed 5/22 = 4 – 6” (H20 = 0.55” – 0.70”)**3
Thu 5/23 = 1 – 2” (H20 = 0.15” – 0.20”)**2
Fri 5/24 = 1 – 2” (H20 = 0.20” – 0.30”)**2
Sat 5/25 = 0”
Sun 5/26 = 1 – 3” (H20 = 0.25” – 0.40”)**2
Mon 5/27 = 0 – 1”
Tue 5/28 = 0”
Wed – Sat 5/29– 6/1 = 0”
May Snowfall = 19.5”
May Forecast = 25 – 30”
Detailed 4-day Snowfall Forecast:
Wed 5/22 —Light snow showers are possible during the day, ending during the evening. Gusty northeast winds. Accumulations 1 – 2” by Thursday AM, 3”+ up top.
Thu 5/23 —Possibly dry during the morning, then snow showers likely by midday/afternoon including a chance for thunder. Any snowfall ends evening hours. Accumulations 1 – 2” by Friday AM; 3”+ up top. Breezy northeast winds.
Fri 5/24 —Dry during most of the day with just a chance for a late PM shower. Light winds.
Sat 5/25 — Possibly dry during the morning, then snow showers likely by midday/afternoon. Any snowfall ends evening hours. Accumulations 1 – 3” by Sunday AM and around 4” up top; Gusty southwest winds.
A cold front moved through Mammoth this morning with strong winds and some snowfall and the associated upper-level low pressure system currently situated over NorCal (image below) will move southward rest of today and into Wednesday into the S. Sierra. That means snowfall will continue at times through tonight with continued light snow showers Wednesday.
Model QPF is over half an inch today and tonight (image below) and that should result in enough snowfall for powder conditions tomorrow. The top might not open tomorrow due to weather and powder conditions are possible there for Thursday morning. Winds will not be as strong as today, but will be gusty out of the northeast.
The ECM model stalls the eastward progression of the upper low on Thursday (image below). Wrap-around flow will likely initiate showers by midday/afternoon hours including a chance for thunder. Snow levels will be around 9K with only an inch or two expected from the showers. GFS model (image below) is showing around half an inch while the ECM has less. Not expected enough accumulation for powder conditions.
Friday could be a dry day other than a chance for PM showers/thunderstorms, then the models move another upper level low pressure system southward into CA on Saturday and into Sunday (images below). That will increase shower activity again with snow levels around 8-9K during the morning and 9-10K during the afternoon thanks to diurnal heating.
Model QPF is not particularly impressive with most of the precipitation staying on the west side of the Sierra and north of Mammoth as the upper level low will be tracking southward off the coast into Sunday. GFS model is showing about a quarter inch (image below) while the ECM is slightly more. The unsettled weather should last through Memorial Day as the upper level low slowly exits eastward.
Right now, the main affect of the passing low pressure system will be to keep temperatures cold for May and continued winter conditions on the top part of the mountain. There could be enough snow for powder conditions above 10K, but probably not below the top of Broadway. It does not look like spring skiing this year for the Memorial Day weekend, although slushy snow is possible at the bottom of Ch 9 that will be running—weather permitting.
Drier weather is then possible by the middle part of next week as the latest ECM model finally moves the upper level trough eastward (image below). Temperatures may stay seasonably cool, but spring conditions should return by mid-week under the strong May sun. With a bit of the trough still remaining over Nevada, there could be enough instability for an afternoon shower, but not snowfall.
The ECM model then has a typical spring pattern by the end of next week with high pressure over the PacNW and a weak trough of Baja (image below). The GFS ensemble is showing another weak undercutting trough of low pressure into CA (two images below), so there is a chance for rain showers unless it ends up much deeper that is doubtful after the current strong late season pattern over the past week.
The GFS ensemble then has a typical spring pattern for early June (image below) with just a weak baggy trough over the SoCal deserts. Expect temperatures to start warming up and the snow to begin melting faster again.
Overall, no more snowfall is expected for the rest of the season starting in June. CFS climate model is favoring near normal temperatures in June (image below) while the ECM model is slightly cooler. If the models are right, I would not be surprised if the season gets extended even longer into mid/late-July due to no prolonged very warm weather.
Have a good summer. WG
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