The new week is highlighted by a change in pattern leading to more seasonal temperatures as our cold weather gives way to the Subtropical Jet…It will be very breezy over the higher elevations Wednesday and Thursday with the slight chance of some light snowfall Thursday and a better chance Saturday Night…..

Monday AM:

Only changes this morning to the discussion below is to highlight the potential of “AR” moisture from the subtropical jet later this weekend.  There is a trend in the GFS of pushing a portion of this off shore AR further north up into Central CA. At the moment it is too soon to forecast any significant AR with any certainty other than to say that a more dynamic system will tap deeper moisture from an AR off the Southern CA coast this weekend….The Dweebs well keep a wary eye on that.

The other change is in the timing of the main precipitation push, which now highlights Saturday Night into Sunday instead of Sunday night. This late weekend storm has the potential of bringing several feet of wetter snow to the upper elevations through Monday with nearly non stop snowfall possibly between its exit and the timing of the passage of the main mother low which may slow down through the 15th and not come through until Friday night the 16th.  We could see another 5 to 9 feet over the crest should all of that happen……Miracle March anyone?

Another comment…..Some times patterns will repeat themselves…Watch for another cold Low that may form off the coast of the pacific NW tapping Arctic Cold that may try to repeat what happened last weekend for around the 19th of March. It is later in the year but well see what shapes up….

For those interested in the snow level….It looks to range from 7500 to 6500 feet later this week. The following week looks to be colder with lighter fluffier snow toward mid-week with lower snow levels.

 

Dr Howard and the Dweebs………………..:-)

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After last weekends monster….The weather will be more tranquil the next few days. There will be periods of wind, clouds and some showers possible by mid-week.  Daytime highs will moderate well into the 40s Tuesday and Wednesday with nighttime lows in the teens and 20s.

Tonight’s new model runs show an interesting analysis at 00z Monday.  Namely, an upper height anomaly that stretches from the Philippine’s, northeast along most shores of the western pacific eastward across the dateline to the Gulf of Alaska.  I see no significant troughing anywhere over the pacific at this time. The pattern highlights two distant polar and subtropical jets. The Subtropical jet is being enhanced over Hawaii and the polar jet around 50 to 55 north just north of the Aleutians, Hawaii looks to be in for some good rain the middle of this week!

The upper polar jet looks to be doing some wave breaking Wednesday and this will cause the current cut off low along 140 west to become stretched out over the next 3 to 4 days. This process will enhance the subtropical jet in its underbelly and extend it to the California Coast by Tuesday/Wednesday. Precipitable water does increase with isotropic lift expected over the colder air. So the chance of mainly light precipitation is expected Thursday into possibly Friday. Again it appears to be quite windy Wednesday over the Crest.

The pattern by the end of this week does become more amplified. The key positive height anomaly amplifies near the dateline and becomes positive tilt over the weekend. This allows the deepening of a significant trough over the Eastern Pacific which kicks out the remains of the old cut off low next Sunday night and Monday. The suggestion is that some decent snowfall will result from that storm. Nothing like what we had last weekend, nevertheless the chance of some moderate snowfall.

Longer Range:

Eventually the large scale Trof that develops later this week comes though itself about the 15th of March with the possibility of a major storm.

 

Dr Howard and the Dweebs………………………:-)

Platinum Powder Alert for Friday and Saturday AM……Storm is highlighted by heavy snow, strong winds and Blizzard conditions Thursday into Friday AM…Storm moves out Saturday leaving Epic conditions Sunday into Monday…..

Platinum Powder Alert for Friday: Between 1 and 2 feet of Platinum Powder (Snow to Water Ratio equal to or greater than 15:1)

Wednesday PM Update:
Winter Storm Warning in effect from March 1, 04:00 AM PST until March 3, 10:00 AM PST
Blizzard Warning in effect from March 1, 10:00 AM PST until March 2, 01:00 PM PST

Town of Mammoth may receive 24 to 40 inches of snow between late tonight and Saturday.
Up to 60+ inches is expected on Mammoth Mountain over the crest Storm total.

 

Bullet points/comments from the new 12Z GFS run this morning.

I have to say that this is quite interesting to see the amount and size of the Arctic Air mass getting pulled southward from the Beaufort Sea north of the Arctic Circle south along the west coast for this time of the year!!  Amazing!!  Do you think that the Sun Spot Minimum has anything to do with that? 😉

Here are the numbers!

At 500mb (18000feet)

  1. -40C to -45C is pulled down over Northwest Territories today.
  2. Huge pool of -35C to -40C is located from the very Northern most California coast north to Prince Rupert Island Canada. That is an amazingly large cold pool for that cold temperature!
  3. -35C cold pool gets as far south as Highway 80 early Friday morning with the southerly push continuing and modifying.
  4. -35C into Reno Saturday AM.

At 700MB 10,000 feet.

  1. Cold Modified Arctic lags the cold at 500MB
  2. -17C is progged into Northern CA Thursday Night
  3. -15C into Reno Friday morning.
  4. -8C to -10C at Mammoth or 14F to 18F Friday AM
  5. Note: there is plenty of vertical motion and moisture to keep the snow going through Friday night.
  6. With the coldest temps aloft Friday afternoon into Saturday AM.
  7. Highest snow to water ratios Friday into Saturday AM.
  8. Sunday to be a Blue Bird Day

 

Longer Range:

 

Subtropical Jet develops off shore next week, Tuesday into Wednesday. Looked at the QPF and it was not all that impressive for Thursday and Friday, only .25 to .50. With that said, it should be pointed out that this is a system with Isentropic lift (upglide) or warm frontal type precip, early on. This pattern may also include a short term “AR”.   Forecast models do not handle this type of precipitation very well, so it is possibly quite under done, QPF wise.  The warm sector precip may begin as early as Tuesday afternoon into Wednesday AM. This is a system that would begin with cold air in place with warming temperatures over a day or two then followed by colder again. Great for avalanches…yes?

 

Dr Howard and the Dweebs…………….:-)

 

Heavy Snow Showers possible Monday Night into the morning hours…..Major snow pattern setting up for Thursday and Friday followed by snow showery weekend….Platinum Powder Watch for Friday….Winter Just getting started….just in time for Spring!

Platinum Powder Watch for Friday…12 inches or more at 15:1 or better….Good possibility for epic weekend for “Platinum Powder.”

Our weather front brought between 4 and 5 inches of snowfall to Mammoth Mt today.  Light fluffy snow!  Second part of the storm is currently developing as weather front has pushed through and somewhat fallen apart.

Upper Trof has now pinched off a closed center which is located over San Jose at 01Z TUESDAY and proged to move SE down the coast and just inland. Looks like a great set up for wrap around upslope snowfall as shown by the 18Z Monday Arizona Regional WRF Model. This model highlights forecasted composite radar which shows the motion of the simulated echos well. So some great upslope is expected this evening from Nevada as a deformation sets up to the north of us and slowly shifts south over night. Amounts will probably exceed what we already have or some 4 to 8 inches additional is possible by 7:00AM Tuesday AM. Then snowshowers will taper off during the rest of the morning…

Expect a break Tuesday night and Wednesday with a chance of snow developing late Wednesday night.. Wednesday’s winds do not look particularly strong but will pick up that night. Highs in the 20s

 

Then we have to deal with possibly of the biggest storm of the winter Thursday and Friday…..

Why do I say that?

Here is why;

  1. The storm has very good over water trajectory
  2. By Thursday afternoon heights at 500MB are forecasted by the ECMWF at 518DM west of the Columbia River
  3. A very large pool of -35c at 500MB is associated with this system stretching for the Vancouver island to Tahoe Friday AM. Its big cold tap is from a pool of -45C at 500MB,  located over the Beaufort Sea north of the Arctic Circle. The cold air eventually invades Mammoth Friday into Saturday AM for some great “Platinum Powder” and lots of it!…
  4. This is a slow-moving storm. It will take at least two days to get through and it will come through in waves.
  5. This is a classic Snow Pattern, especially for the Northern Sierra. The air mass it is coming into is already cold and so there will be a lot of snow in places that do not usually get a lot of snow at one time like RENO and Carson City.  Today guidance suggests 4 to 8 inches possible in those valleys by Saturday AM according to the NAM FOUS today.
  6. Winds…..The big winds arrive Thursday night with peak winds Friday morning. With the very dry snow and lots of it, combined with high winds….blizzard conditions are likely to develop with possible road closures, sometime between Thursday night into Friday along highway 395.
  7. Total snowfall accumulations 3 to 5 feet between Thursday morning and Saturday PM
  8. This will be an epic weekend for “Platinum Powder”.

Longer Range:

Based Upon both ECMWF and GFS; PWAT…500MB heights and 200Hpa winds. Opportunities for Subtropical jet and then both polar and subtropical jet confluence. (March 8th thru 14th and 11th thru 13th) Potential AR Events?

These will be warmer and wetter systems…still snow over the upper elevations….

Hang on…..The Dweebs said that winter would arrive in late February and March…….:-)

 

Dr Howard and the Dweebs………………………….:-)