Friday January 13th, 2017
Ted Schlaepfer CCM —- Mammoth Mountain WeatherGuy
The storm cycle has ended and dry weather will return over the weekend under seasonably cold temperatures with just a chance for flurries Sunday. Dry and warmer weather is expected early next week before snowfall returns on Wednesday. Heavy snowfall is expected again early Thursday followed by another storm Friday that will have dry powder for Saturday. Snow showers probably continue over the early part of the weekend before more snowfall likely returns by early the next week. There could then be another break toward the last part of the month with a chance for storms to return by the end of the month and early February. Longer range models are suggesting that drier weather could return over the first week of February and last into mid-February.
Next update Tuesday 1/17.
Snowfall forecast are for the Sesame snow course (Main Lodge)
**Snowfall forecast confidence ranges from very low (1) to very high (5)
Sat 1/14 = 0”
Sun 1/15 = 0”
Mon 1/16 = 0”
Tue 1/17 = 0”
Wed 1/18 = 1 – 3” (H20 = 0.15 – 0.25”) **3
Thu 1/19 = 21 – 26” (H20 = 2.10 -2.50”) **3
Fri 1/20 = 6 – 9” (H20 = 0.50 -0.75”) **3
Storm Total = 24” – 36” (H20 = 2.75 – 3.50”) **3
Sat – Mon 1/21 – 23 = 20 – 30”
January Snowfall = 141.5”
January Forecast = 175 – 200”
Detailed 5-day Snowfall Forecast:
Sat – Tue 1/14 – 17 — No snowfall expected all days except chance flurries Sunday.
The low pressure system that produced over two feet of cold, dry powder at Main has now mostly exited the area with some wrap-around flow today keeping skies cloudy. Those clouds will clear out tonight for a blue bird morning with the top likely to open with continued seasonably cold temperatures.
The weather will mostly be dry for the next few days. A weak short-wave (image below) moving southward along the western periphery of the long-wave trough situated over the Southwest under generally split jet stream flow will likely to be too far west to produce much more than clouds and flurries Sunday PM. High pressure will then build into the region Monday and into next week for fair and warmer weather.
All the models, including the Canadian now (although it is slower and weaker), move a full latitude trough (image below) southward into the West Coast with the trough splitting when it moves into CA and plenty of energy in the southern split. The system will contain a remnant AR and will have plenty of moisture to produce hefty snowfall and there is also cold air and snow levels will be low enough at the start at 7K for it to be all snow on the mountain and town.
As the trough digs southward, moist upslope flow will against the Sierra will produce snowfall early Wednesday with snowfall increasing during the day and into Wednesday night. There could be six inches on the ground by Wednesday afternoon with winds also increasing during the day.
Heavy and strong winds are expected again Thursday during the day (riders of the storm, although winds may limit lift operations) with snow forecast to taper off Thursday night. Model QPF is generally between 2.5 – 3.5” liquid with the majority falling Thursday early morning and into midday. The GFS model below is showing around 2” for Thursday with the ECM around 2.5”. Thinking that about 2-3 feet will fall at Main and 4 feet plus up top.
Friday will be a powder day with more snowfall expected by midday or early afternoon. A trailing short-wave trough (image below) will move southward in the flow into CA Friday and into Saturday for another round of snowfall. This upper low is colder and will produce another dose of cold, dry powder as snow levels will get down to near 3000 feet.
The ECM shows almost two inches liquid with this system with snowfall continuing at times Saturday before ending Sunday morning with possibly up to 30” new. The GFS only shows about 1” liquid or around 15”. The ECM mean is closer to the operational model and shows enough liquid precipitation for at least two feet at Main. The forecast generally follows that guidance, but it is still a ways out and that will likely change.
Models then diverge for early the following week. The GFS model (image below) moves the ridge northward from off the SoCal coast and pushes the jet stream track into Oregon.
The ECM operational model is completely different. It has a deep trough off the coast and the moist jet (purple arrow) pointing into the Sierra with a front moving ashore into the Bay Area Monday morning. The models also differ in the East Coast with the ECM showing a ridge in E. Canada while the GFS has a weak trough.
The ECM ensemble mean is showing a trough as is most of the ensembles and the GEFS, unlike the operational model, is showing zonal flow much farther southward (image below) with the moist jet pointing into the Sierra. Thus, the forecast right now favors more snowfall early over the following week, and it could be significant. Looks like there will be another storm cycle starting middle of next week, although probably not as strong as this last one when 21″ liquid and over 140″ of snow fell at Main over 10 days.
Longer range guidance favors ridging and dry weather to return by the end of that week (image below), although there is a good amount of spread in the ensembles and there is a chance for more storms. The climate models shows a chance for storminess to return end of January and early February before hinting at a longer dry spell possibly heading into mid-February. Overall, looks like the feast of new snowfall will continue for a while. WG