Powder Forecast — Tuesday March 21st, 2017
Ted Schlaepfer CCM —- Mammoth Mountain WeatherGuy
Snow tapers off this evening and ends overnight before starting again late tomorrow morning and lasting through the afternoon, ending Wednesday evening. Thursday will be dry, then more snow arrives by Friday afternoon and continues overnight. A couple more inches of snow is then possible Sunday night before dry weather returns next Monday and Tuesday. Other than a slight chance for light snow middle/end of next week, dry weather is generally favored through early April with just a slight chance around April 4-6th. Longer range climate models now say mostly dry weather will continue into mid-April with storm chances increasing around second half of the month.
Next update Friday 3/24
Snowfall forecast are for the Sesame snow course (Main Lodge)
**Snowfall forecast confidence ranges from very low (1) to very high (5)
Wed 3/22 = 8 – 10” (H20 = 1.00” – 1.20”)**4
Thu 3/23 = 2 – 4” (H20 = 0.25” – 0.35”)**4
Fri 3/24 = 0”
Sat 3/25 = 8 – 10” (H20 = 0.80” – 1.00”)**3
Sun 3/26 = 0 – 1”
Mon 3/27 = 2 – 3” (H20 = 0.25” – 0.35”)**4
Tue 3/28 = 0”
Wed – Fri 3/25 – 27 = 15 – 24”
March Snowfall = 12.5”
March Forecast = 35 – 45”
Seasonal Snowfall = 522.5”
Seasonal Forecast = 575 – 600”
Detailed 5-day Snowfall Forecast:
Wed 3/22 — Light snow likely develops by the afternoon and continues into the evening hours. Accumulations 2 – 4” by Thursday AM. Up to 6” up top.
Thu 3/23 — No snowfall expected.
Fri 3/24 — Snow likely develops by the afternoon and continues overnight. Accumulations 8 – 10” by Saturday AM. 12”+ up top.
Sat 3/25 — Snow showers end during the morning or early PM hours. No accumulation expected or maybe an inch.
A cold front moved through Mammoth today (satellite image below) and a wet-type snow is still falling as of this writing with a post-frontal trough expected to move through late this afternoon and evening for a couple more inches before snowfall tapers off and ends overnight.
The main upper level low pressure system associated with the front is still offshore and it will move toward the coast tonight and into interior central CA tomorrow afternoon. Unfortunately, the low will be weakening and most of the energy will also be moving south of Mammoth in a split flow and thus dynamics for snowfall to make it to the eastern side are weak.
Models are only showing about 0.20”- 0.35” with the ECM model the wetter one. It looks like just light snow tomorrow afternoon and evening before snowfall ends overnight. Probably just a few inches at Main and maybe up to six inches up top that might not open tomorrow.
Thursday will be a break between storms with a bluebird morning expected in Mammoth. Snow levels will lower with the storm tomorrow and freezing levels should only come up to about 8.5K Thursday, so it should be a nice day on the hill with the new snowfall.
Models are still advertising another storm system for Friday and into Saturday, although they have unanimously backed off on the intensity. The upper trough is now forecast to be weaker and it will split per the ECM model (image below) when is moves inland Friday night and early Saturday.
The latest 12Z ECM is still showing about an inch of QPF and the latest ECM mean has only slightly less. The GFS is showing much less now and has less than half an inch. The Canadian model is closer to the ECM.
The current forecast favors a blend of the ECM mean and operational models with up to an inch of liquid and around 10” at Main with 12”+ up top. It will be a mild storm again and snow will not be dry quality. Snowfall should end Saturday morning with partly cloudy skies by the afternoon.
There could be one last system brushing Mammoth on Sunday night (image below) with most of the impacts likely staying north. Only expecting an increase in winds and light snowfall that maybe will result in a couple of inches by Monday morning when any snow showers should end.
High pressure will then build over the area through at least Tuesday for fair and dry weather and it will probably continue for the rest of the month. Models do bring another short wave southward into the interior West by the end of the week, but only the Canadian model (image below) has it far enough westward for any snowfall and it would be light at best.
The operational GFS and ECM (image below) models both suggest it will be an inside slider type storm and will just increase the NE winds and maybe slightly colder temps for a day or two. These storms are typically moisture starved and don’t produce significant snowfall.
The GFS spaghetti ensembles (favor) the insider slider solution with only a couple solutions showing an over water trajectory. It is still a week out, but right now, chances don’t look good for more powder conditions after this weekend. It could be awhile.
The GFS (image below) and ECM ensemble both favor the high pressure ridge to nudge eastward off the Pacific toward CA by the end of the month. That means fair and dry weather with seasonable temps with any potential inside slider type lows staying far to the east.
The longer range GFS ensemble says chances increase by the 5th (image below) for one of these lows to drop southward farther west along the coast. That could be the next chance for any snowfall, although right now chances for a big storm are slim.
This pattern could hold until close to mid-April now says the climate models. The ECM keeps the mean trough too far east through the 10th and then too far north through the 16th for any big storms before developing the trough in a better position after mid-month. The CFS model is a bit faster with the trough developing in a better position by mid-month, but the model is not particularly wet overall for the month (image below) showing slightly below normal precipitation by about an inch.
Good thing is these models are not great in the long term. That will probably be especially true considering an expected flare up of tropical convection associated with an abnormally warm Nino Index region 1.2 near Peru where devastating floods have occurred lately. There will be some powder days in April and we will figure out when soon. WG