Powder Forecast — Friday February 24th, 2017

Friday February 24th, 2017

Ted Schlaepfer CCM  —- Mammoth Mountain WeatherGuy

Forecast Summary:

 Partly cloudy and seasonably cold weather continues through the upcoming weekend with only flurries expected until early Monday when a period of light and dry snowfall is possible with maybe up to 6” of total accumulation.  A period of quiet and dry weather is then expected for the rest of next week and through the following weekend or longer.   Next chance for any snowfall would be around March 10-11th with generally dry weather favored through mid-March.  No clear signs of any storm cycles through the third week of March or longer.

Next update Tuesday 2/28

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


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

Sat 2/25 = 0”

Sun 2/26 = 0 – 1”

Mon 2/27 = 2 – 4”

Tue 2/28 = 2 – 4”

Wed 3/1 = 0”

Thu 3/2 = 0”

Fri 3/3 = 0”

Sat – Mon 3/4 – 6 = 0”

February Snowfall = 162.5”

February Forecast = 165 – 170”

Seasonal Snowfall = 496.5”

Seasonal Forecast = 575 – 600”

Detailed 5-day Snowfall Forecast:

Sat 2/25 — No snowfall expected through the morning, then flurries possible during the afternoon and at night, no accumulation expected or maybe an inch by Sunday AM.

Sun 2/26 — Flurries possible early AM, then dry until late Sunday night when light snow is expected to begin.   A few inches of fluffy accumulation possible by Monday AM.

Mon 2/27 — Light snow during the day, mostly AM, ending overnight.   A few inches of fluffy accumulation possible by Tuesday AM, 6”+ up top

Tue 2/28 — No snowfall expected.

Forecast Discussion:

Short Term:   

    There is a nearly stationary area of low pressure in the central Pacific northwest of Hawaii with a strong and anomalous high pressure ridge building into the Gulf of Alaska that is all part of a Rex Block (image below).    A high latitude and cold upper level low pressure system now positioned off the PacNW coast has moved around the building ridge and is currently tracking southward.

   It the last update, the models were showing the cut-off in the Pacific either merging with the southerly tracking cold low pressure system or at least feeding needed moisture into the low that are defined by the lack of large PWs (precipitable water plumes) having originated in the Arctic.

   The latest ECM model (image below) run shows that the low pressure systems will not be merging now with the current low off the PacNW taking a track into SoCal with the other low pressure system remaining separate and off the coast.   There could be some flurries or light snow showers Saturday afternoon and night, but no significant snowfall expected with the only outcome continued seasonably cold temperatures.

  A second and stronger high latitude trough will move southward on Sunday and Monday and that low will also not merge with the offshore low.  That second and stronger low will move into the Sierra early Monday (image below) and there will be enough dynamics to squeeze out some snow from the limited moisture.

   The ECM and Canadian are the most bullish about some light snowfall with the ECM showing about a third of an inch QPF total.  But with snow ratios in the 20:1 range under the very cold air mass that could mean six inches of fluffy dry snowfall by midday Monday which might not be dust on crust considering the already soft snow conditions under the current cold temps.

   Any snowfall ends by Tuesday morning with the models showing a high pressure ridge building into the West Coast by the middle part of next week (image below).   That means the return of fair and dry weather.

 Long Range:

   The 12Z Friday run of the ECM model is showing the high pressure ridge to continue to build for the rest of next week and through the following weekend (image below).   It suggests that temps will slowly rise back to seasonal normal levels by the end of the week and remain fairly steady or warm slightly through the first weekend of March.

   The longer range ensembles are then favoring that ridge to generally hold firm for most of the following week before a weak trough may be able to move into the West Coast and CA again toward the end of that week (image below).   So it looks like at least 10 days of dry weather in early March with that chance looking rather weak right now with any storm probably staying to the north of Mammoth.

    The dry weather is generally favored to last through mid-March according to both the CFS and ECM climate models. The CFS model is showing below normal precipitation through the middle of March (image below) and the ECM is similar.   The models even show dry weather beyond that too, but skill beyond 3 weeks is garbage and even a week three forecast has limited verification skill.

   Overall, after a chance for some light and dry powder (but not deep) on Monday, there are no clear signs of any powder days through the middle of March or longer.   Good news for the local residents who are currently buried, bad news for the powder hounds.   WG

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Powder Forecast — Monday February 20th, 2017

Monday February 20th, 2017

Ted Schlaepfer CCM  —- Mammoth Mountain WeatherGuy

Forecast Summary:

  Snow mostly continues through this evening before becoming heavy again overnight and early Tuesday with continued snow showers through Tuesday evening and into Wednesday morning.  Light snow showers or flurries and colder temps are then expected Wednesday and Thursday with a dry/cold day Friday.   Then there is a chance for snow again by Saturday night and at times through early the following week with dry weather possibly returning in early March.   Longer range climate models are saying no big storms through the second week of March with mostly dry weather into mid-March.

Next update Friday 2/24

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


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

Observed snowfall Feb 17 – 20th  = 46” (H20 = 3.88”)

Tue 2/21 = 25 – 28” (H20 = 3.00” – 3.50”) **4

Wed 2/22 = 12 – 15” (H20 = 1.25” – 1.50”) **4

Thu 2/23 = 0– 1” (H20 = 0.05” – 0.10”) **4

Storm Total = 83 – 90” (H20 = 8.23” – 8.98”) **4

Fri 2/24 = 0”

Sat 2/25 = 0”

Sun 2/26 = 6 – 10”

Mon – Wed 2/25 – 27 = 15 – 24”

February Snowfall = 123.5”

February Forecast = 180 – 200”

Seasonal Snowfall = 457”

Seasonal Forecast = 600”- 625”

Detailed 5-day Snowfall Forecast:

Mon 2/20 — Snow becomes heavy again overnight and early Tuesday.   Total daytime and overnight accumulations 25 – 28” by Tuesday AM.  Close to 40”+ up top.

Tue 2/21 — Snowfall continues during day before tapering off Tuesday night and into Wednesday.   Accumulations  12 – 15”  by Wednesday AM.  18”+ up top.

Wed 2/22 — Snowfall mostly ends during the morning with only light snow showers or flurries the rest of the day and night.  Colder.   No significant accumulations Wednesday.

Thu – Fri 2/23 – 24 — No snowfall expected both days.

Forecast Discussion:

Short Term:   

    Satellite imagery below shows a strong area of low pressure moving into NorCal this afternoon with moist southwest flow into the Sierra producing clouds and snowfall in Mammoth this afternoon with should continue at times into the evening.  The cold front will move ashore overnight and heavy snowfall should develop again in Mammoth after mid-night and early Tuesday.

    Over an inch and a half of liquid and 10” of snow has fallen since this morning and the GFS model says about 3” more liquid should fall rest of today (image below) and Tuesday (image 2 below). I am expecting 15”+ more snowfall through tonight and about a foot Tuesday and Tuesday night before snowfall tapers off early Wednesday.  Storms totals back to end of last week will end up around 7 feet at Main.

   Snow levels have risen to near 7500 feet this afternoon and have maxed out and should fall below 7000 feet tonight and then below 6000 feet on Tuesday and 4K Wednesday.  Nonetheless, it will still be a Sierra cement type snow and not dry powder into Tuesday before colder air filters into the area during the day Tuesday for better snow quality at the tail end of the storm as the models bring cold air into the Sierra under NW flow by Thursday (image below).

   The snow mostly ends Wednesday with just flurries or light snow showers into Thursday as one last weak wave moves through the Sierra.   Temps will continue to get cold Thursday and will be quite cold during the morning hours.   Dry and cold weather continues Friday with roads likely staying snow covered as the weather stays seasonably cold.

Long Range:

   The models have mostly come into agreement about the last few days of February after considerable disagreement in the last update, although they still differ on the details.  The ECM was the last on board and it now shows an upper level short wave move south around a building high pressure ridge in the Gulf of Alaska where it readies to merge with a low in the eastern Pacific (image below) around Saturday.

    That model merges the low pressure systems by Monday (image below) resulting in a deep and cold upper level low pressure system right over central California.  It has heavy snow Sunday and Monday and showers continuing into Tuesday.  It has about 4” of liquid with snow levels averaging around 4500 feet.   That could be close to 4 feet at Main.  The Canadian is generally similar or only slightly less.

   The GFS model is a bit different though.  It has the upper level low pressure system moving southward from the Gulf, but it doesn’t phase the two systems together like the ECM with a lot of the moisture not entraining into the upper level low pressure system before landfall in addition to being more progressive with its departure.  Nonetheless, it has about a foot on Sunday (image below) with QPF over an inch.

   The current forecast follows the latest 12Z run of the ECM ensemble mean which shows a pretty good storm on Sunday into Tuesday with a combined 3 day QPF total of about 2.5” liquid or at least two feet at Main.  That model also favors snow levels mostly below 5000 feet with the event resulting in a good chance that the snow quality will drier.

    I’m sure the details will change, but it looks like more snow next weekend and there is a chance that February will end up near or above 200” now. The models are then showing high pressure building for at least a couple days during early March with a mixed signal toward the end of the first week.   The latest GFES spaghetti ensembles are all over the place with some solutions showing a ridge, others a cold trough, and a few potential storms.

  Thus confidence is low in the forecast for the first part of March.  I think the cold trough solution across the interior West is the best guess right now as the MJO will be in phase 2 (image below) which is favored by the composites.  That means there could be cold lows moving into the Sierra or just east of the range with the systems having limited moisture.   If the MJO moves into phase 3 in early March and holds strength as some ensembles suggests, we could get wet again instead.

   But that is not what the climate models are showing as both the CFS and new ECM show ridging occurring by the second week of March for mostly dry weather.   Both models are showing slightly below average precipitation (image below) into mid-March, so there is a chance for an extended dry period next month.   Unfortunately, those models have not done well this winter with many of the projected dry periods ending up wet. It has to stop snowing sometime, right?  WG

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