Mammoth Mountain Weather Forecast – March 21st 2017

Powder Forecast — Tuesday March 21st, 2017

Ted Schlaepfer CCM  —- Mammoth Mountain WeatherGuy

Forecast Summary:

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.

Forecast Discussion:

Short Term:   

    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.

Long Range:

  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

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Mammoth Mountain Weather Forecast — Friday March 17th, 2017

Powder Forecast — Friday March 17th, 2017

Ted Schlaepfer CCM  —- Mammoth Mountain WeatherGuy

Forecast Summary:

 Dry weather continues into Saturday with lots of clouds over the weekend and a chance for flurries during the late afternoon/evening on both Saturday and Sunday, but no significant snowfall.  Snowfall probably develops by late Monday and Tuesday next week with another storm possible toward the end of next week and into the following weekend.  Longer range climate models say colder type storms could then continue at times into mid-April with periods of dry weather as well.

Next update Tuesday 3/21

Snowfall forecast are for the Sesame snow course (Main Lodge)

**Snowfall forecast confidence ranges from very low (1) to very high (5)

Sat 3/18 = 0”

Sun 3/19 = 0”

Mon 3/20 = 0 – 1”

Tue 3/21 = 0 – 3”

Wed 3/22 = 9 – 12” (H20 = 1.00” – 1.50”)**3

Thu 3/23 = 2 – 5”

Fri 3/24 = 0 – 3”

Sat – Mon 3/25 – 27 = 15 – 24”

March Snowfall = 10.5”

March Forecast = 40 – 55”

Seasonal Snowfall = 520.5”

Seasonal Forecast = 600 – 625”

Detailed 5-day Snowfall Forecast:

Sat 3/18 and Sun 3/19 — No snowfall expected both days except for a chance for afternoon/evening flurries.

Mon 3/20 — Probably dry during the day, then snow develops late night or early Tuesday.   Accumulations up to 3” by Tuesday AM.

Tue 3/21 — Snow is likely during the day and probably continues at times overnight and into Wednesday.  Riders of the storm day.  Accumulations up to 9 – 12” by Wednesday AM.   Over a foot up top.

Forecast Discussion:

Short Term:   

    A high pressure ridge (image below) is centered over the southern part of the state today with an area of low pressure in the Gulf of Alaska off the British Columbia coast and associated frontal system that is connected to a weaker area of low pressure well off the CA coast.    Both of those systems are slowly moving eastward.

   Models say the weak low will generally fall apart when it moves ashore into NorCal tomorrow (image below) while the upper low in the G.A tracks into the PacNW.

  Nonetheless, it will knock the high pressure ridge eastward Saturday for colder temps (freezing level lowers to 9K) and clouds will be drifting over Mammoth at times both Saturday and Sunday for periods of flat light.  No snowfall is expected other than a chance for afternoon/evening flurries.

  The models per the GFS below then moves a stronger trough of low pressure toward the coast Monday and into Mammoth by Tuesday as split jet stream flow develops along the West Coast.   Since the last update, the models have fluctuated with whether the system will split apart further when it moves onto the coast and not have an organized frontal passage.

  The latest GFS still has over an inch of liquid Tuesday (image below) for about a foot of snow and the 0Z run of the ECM is similar while the Canadian is much slower with the eastward movement of the low and delays snowfall by about 12-18 hours from Tuesday into Wednesday.

   So there is still some uncertainty with strength and timing, but it does look likely that it will snow by the middle part of next week and powder conditions will return to the mountain.  Snow levels won’t be too low and around 7K so the snow won’t be dry quality.

Long Range:

  There might not be a trailing system for Wednesday now per the latest GFS guidance with a break in snowfall through Thursday, and unfortunately, the 12 UTC run of the ECM model suites was very late today and not available as of this writing.

   However, the models are still advertising a stronger storm system for the end of next week and into the following weekend and it may contain a weak AR.   The GFS brings a more cohesive upper level low pressure system to the coast next Friday (image below) with snowfall developing Thursday night.   The 0Z ECM was similar and only slightly slower with the start of snowfall delayed til Friday AM.  The Canadian is similar to the GFS.  It is a week out so details will likely change.

   All the models are suggesting at least two inches of liquid precipitation with last night’s run of the ECM showing close to 3”.   So it looks like this storm has the potential to drop up to two feet at Main over a couple of days with snow levels projected to be in the 5-6K range likely resulting in normal type Mammoth quality snow (not too wet, not too dry).

   Last night’s ECM brings a kicker upper low into CA late Sunday and into the following Monday for a chance for more snowfall, but the other models are not showing it with ridging instead.   The GFS ensemble shows ridging which is probably the best guess right now considering no ECM ensemble today.

   The 12Z GFS operational model splits a short wave southward from the jet stream (image below) just before mid-month which would represent another chance for snow.  I certainly don’t believe that exact solution yet, but the models are not favoring quick ridging back over CA.

  The GFS ensemble is favoring a trough over CA/interior West (image below) to start April which would allow cold storms to move into CA, which is what was favored in the last update.  However, the GFS has the trough farther westward now which gives the lows a better chance for over-water trajectory to pick up need moisture to produce snowfall.

   The ECM climate model is still showing some form of a trough over the interior West into mid-April. The model is generally showing average precipitation for the period.  So there will be storm chances at times with lows dropping southward from the Gulf of Alaska with probably dry weather too.   This type of pattern is cool, so snow melt over the first half of April may be slow.  WG

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