Tuesday January 17th, 2017
Ted Schlaepfer CCM —- Mammoth Mountain WeatherGuy
Another borderline major storm cycle starts tomorrow and lasts through the weekend with three storms and multiple waves of snowfall affecting Mammoth into next Monday. The heaviest periods of snowfall are expected early Thursday, Friday during the day, and Sunday during the day and Sunday night with breaks between storms. Dry weather likely returns next Tuesday and probably lasts for the rest of the month and into early February. Longer range models are suggesting that storms could then return by late in the first week of February or over the second week and could linger into mid-February.
Next update Friday 1/20.
Snowfall forecast are for the Sesame snow course (Main Lodge)
**Snowfall forecast confidence ranges from very low (1) to very high (5)
Wed 1/18 = 0”
Thu 1/19 = 10 – 12” (H20 = 1.00” – 1.25”) **4
Fri 1/20 = 2 – 4” (H20 = 0.20” – 0.35”) **3
Sat 1/21 = 16 – 20” (H20 = 1.25” – 1.50”) **4
Sun 1/22 = 3 – 5” (H20 = 0.25” – 0.50”) **3
Mon 1/23 = 30 – 36” (H20 = 3.50” – 4.0”) **3
Tue 1/24 = 2 – 4” (H20 = 0.20” – 0.40”) **3
Storm Series Total = 63” – 81” (H20 = 6.40” – 8.0”) **3
Wed – Fri 1/25 – 27 = 0”
January Snowfall = 141.5”
January Forecast = 200 – 215”
Detailed 5-day Snowfall Forecast:
Wed 1/18 — Snow flurries in the morning turns to steady snow by the late afternoon with a period of heavier snow overnight. Accumulations 10 – 12” by Thursday AM, ~18” up top.
Thu 1/19 — Snow showers taper off during the day, end by evening, not much accumulation or storminess during operations. Snow begins again late at night. Accumulations 2 – 4” by Friday AM, ~6” up top.
Fri 1/20 — Snow, heavy at times, during operations with continued snow at times overnight and into Saturday. Riders of the storm day. Accumulations 15 – 18” by Saturday AM, 24”+ up top.
Sat 1/21 — Snow showers taper off during the day, end by evening, storminess during morning operations mostly with a few inches accumulation. Snow begins again overnight. Accumulations 3 – 5” by Sunday AM, ~9” up top.
The dry period of weather that started last weekend will come to an end tomorrow as the next storm cycle begins with three storms over the weekend and into Monday next week. Not as much precipitation is expected this time, but it will also be an all snow event for the mountain and town as snow levels will stay below 7000 feet for the entire period. Current projects are showing about 5-7 feet at Main and possibly close to 10 feet up top for the entire storm period.
Models are showing the first upper level low pressure system (image below) splitting from the jet stream tomorrow afternoon with energy in the southern split moving into the Sierra tomorrow night. This storm will be the primer for the subsequent storms to follow.
Snow flurries will probably begin tomorrow morning with snowfall increasing late afternoon and evening before a period of heavier snowfall occurs late at night and turns to showers around dawn Thursday, ending Thursday PM. GFS (image below) and ECM models are similar with around 1.25”-1.50” liquid precipitation expected from the relatively fast moving front. Snow levels start around 7K Wednesday morning and lower to around 5.5K when the front moves in, and then down to 4.5K Thursday AM. It will be typical Mammoth snow and not cement.
There will likely brief break Thursday evening and into the night before snowfall redevelops by dawn Friday. Snow, heavy at times, is then expected during the day and through Friday night. The upper level low pressure system (image below) is being driven by the polar jet (blue arrow) and is very dynamic. It is an usual pattern in that the 500-mb heights will get unusually low for CA with a geopotential height of 534-dm expected in Mammoth Friday PM.
That means it will be the colder storm with snow levels likely near or below 3000 feet and that the snow will be cold, dry powder. Not super dry like Utah, but certainly dry enough for easy turns with Friday a “riders of the storm” day and this storm might not be too windy to cause a shut-down of lift operations. There could be epic skiing/riding around Ch. 22 by midday with refills all afternoon.
The GFS and ECM are similar again with QPF and are showing about 1.25” liquid and up to 1.75”. Expect more than a foot of snow at Main with probably around 18” and an outside shot at a two foot dump with at least two feet of powder up top by Saturday morning when the snow tapers off and ends Saturday night.
That break will also be brief as the third and final storm develops off the coast early Sunday with moist up-slope flow increasing Saturday night and snow developing by dawn Sunday. The upper level jet aligns into a southwest flow (image below, purple arrow) which is the ideal flow for orographic enhancement over the Sierra and particularly the San Joaquin drainage basin in which Mammoth lies on the eastern side.
That means that the third storm will be the wettest of the three with model QPF in the 3.50-4.50” range. The GFS model (image below) is slightly wetter than the ECM and shows about 4” for Sunday with additional precipitation into Monday when the upper low moves through the Sierra. Snow showers should continue through Monday and into early Tuesday.
Snow levels will start out low tand around 4K Sunday with the cold air in place from the previous storm. Levels will rise to near 6K Sunday evening before lowering again overnight back down to below 3000 feet early Monday. The snow will not be cement even though it has a subtropical tap and will be typical Mammoth powder with drier powder moving into the Sierra at the back end of the storm Monday morning.
Overall, this last storm may dump around 3 feet at Main and up to 5 feet up top by the time the snow ends Tuesday morning. It could be a riders storm Sunday, although this storm may be the windiest storm and lift operations could be severely affected since the brunt of the storm and wind moves through during the day Sunday.
All the models are showing a ridge of high pressure (image below) building into California by the middle part of next week and holding for the rest of the week and into the following weekend for fair and dry weather.
Longer range ensembles (image below) are also favoring that the ridge along the West Coast will hold into early February as the global pattern shifts and a deep trough develops in the East Coast, something that has not occurred too often this winter and was common during the height of the drought.
So it looks like the upcoming stormy period will be the last storms for January which could be a record setting month. January 2017 will likely break the January record for most snow (182″ Jan 1995) and could break the all-time monthly snowfall record of 209 inches from December 2010, the last big snowfall season.
The ECM and CFS (image below) climate models are saying that the global pattern shift will be short-lived and that storms could return by end of the first week of February and then could last into the middle part of the month. That is a long ways out, but it seems like the global patterns are favoring the West Coast this season and I would not be surprised that the models may be right. WG