Archive for year 2020

Will SSW be the Trigger that Saves California from drought this year?

A “Major” Sudden Stratospheric warming event is underway over the Arctic at the moment. One that may change the course of one the driest beginnings of Winter to the Central and Southern Sierra in years…..  The SSW, (Sudden Strato Warming Event) is a process that can rapidly warm the stratosphere of over 100F at times, caused by planetary wave breaking (Rossby Waves) that propagate up into the Stratosphere. The sudden heating of the Stratophere creates high pressure over the polar region that can dislodge the polar vortex or even breaking it up into smaller vorticies sending them south “toward” the mid latitudes. All in all, the main effect is a southward adjustment to the Polar Jet, which is in the end, what we want to get winter going!   Thus far this winter, the polar jet has been over the Pacific Northwest, south to Northern CA.,   This is a reason why Mammoth has not received much in the way of precipitation. La Nina has effectivly blocked and/or weakend the MJO from periodically forcing the usual wet patterns that develop along the southern and central west coast, The SSW may be our savior that adds a northern latitude variable to the equation of getting the upper jet well south into CA.   Here is a link to more information on the SSW; https://www.severe-weather.eu/global-weather/stratosphere-major-winter-warming-watch-january-2021-fa/   

COMMENT:    By the looks of what is going on over the Arctic with its strong height rises in the global models and a massive PV headed south over East Asia, this is going to be a big deal for the Central West Coast this January, as the Extension of the East Asian Jet progresses to the west coast with some very signifacant “Atmospheric Rivers”.

The Screaming message here is that Winter is coming!!

 

Dr Howard and the Dweebs……………….:-)

A transitory Ridge to bring a Sunny Day Wednesday…Followed by increasingly cloudy sky’s Thursday….Active pattern to Resume Friday night into early next week….Snowfall amounts in the light to moderate amounts……..

12-25-2020

Models have come in drier with system tonight and Saturday..   1 to 6 inches over the Sierra at elevations above 6500 feet.

next system is colder for  Sunday night and Monday..  However, it too will be a light precip producer for the east side. Two to 6 inches……

it will be colder than normal the next week….

 

Outlook shows a series of fast moving storms affecting mammoth through mid January.  All in the light to moderate range for snowfall….

Dr Howard and the Dweebs….

 

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I. As we approach the end of the year….There appears to be 3 more weather systems that will bring snowfall to the high country;

  1. The Christmas Day Eve system
  2. The Sunday/Monday system
  3. The New Years Eve system

II. Currently off shore we have a mid latitude upper high that will make its way onshore today. So a beautiful day it will be with highs in the 40s.  Winds over the crest will diminish as well. To the south of this ridge is a weak subtropical low that is getting the boot from an upstream upper jet.

Currently our airmass is very dry, This weak subtropical low will serve to juice up our airmass for the next two systems arriving over the weekend.

The Friday Night system into Saturday will bring mainly light to moderate amounts of snowfall.   The Freezing level; in town will begin at about 8K, but will lower over night.  So early in the system it will be very wet snow.  The Structure of the the upper jet shows two branches. One the polar and other subtropical. The southern branch favors Mammoth with most of the dynamics remaining to our north, La Nina style.  CRFC QPF is showing .79 inches for Yosemite and about the same for Huntington Lake. That suggests 4 to 8 inches on the mountain with some 2 to 4 in town by Saturday afternoon.

There will be a break between short waves, with the next system splitting and diving south during the day Sunday. This 2nd system is problematic due to the nature of the split. It will favor the Southern Sierra. So more time is needed to provide better accuracy in the QPF. I will update for the Sunday night/Monday system on Christmas Day….

The last system for 2020 is expected “about” New Years Eve. Potentially it could be a major storm as a pattern change involving retrogression of the eastern pacific (long wave) ridge to the dateline is being suggested in the longer range guidance.

 

Tropical Forcing:

Although the MJO has not been a positive force because of La Nina’s destructive interference of the tropical mode, there is evidence that other modes of tropical variability are in play, These may be  affecting the extra tropics. There has been atmospheric wave breaking (Equatorial Rossby Wave Breaking) over the Indian ocean as touted by the CPC. These Tiny Dancers may be influencing the mid latitude circulation to some extent.

 

Life is good on the Dark Side of the Sun………….

Today’s a special day…  It’s the shortest day of the year in the Northern Hemispheric. The suns rays are at their greatest angle away from us…Our day-light is at its dimest…..It feels like were on the Dark Side of the Sun…..  However, its a very special night tonight as the Grand Conjuction of both Saturn and Jupiter will cause both planets to appear as one. Catch it,  when skies darken tonight, in the southwest above Mammoth Pass….

An approaching inside slider has brought breezy conditions to Mammoth Lakes this afternoon. It will turn colder the next couple of days, however, the system is very progressive and its quick departure will not likely allow any precipitation to the high county. A quick dump of cold air is likley, followed by a short wave ridge to cap it off…..

Further out in the pacific is a small wave that has become pinched off, will spread high clouds over our area beginning later Wednesday into Christmas Eve. Precipitation is not expected from this weak system. Further out time wise, an approaching upper jet will act to consolidate the upper flow over Central and Northern CA by Christmas Day Eve.  The jet will carry a lot of moisture with it. However, threre will not be any cold air advection as the upper jet is to the north of us. So littel in the way of any dynamics. Preliminary EST Snowfall amounts look to be in the light range with some 3 to 6 inches.  Will fine tune over the next few days. Precip looks to fall primarially between Friday night into Saturday with the snow level aroud 6000 to 7000 feet. The Owens Valley looks to be shadowed out from this system.

The following system looks more dynamic for later Sunday into Monday….Potentially, that may be a better snowfall producing weather maker.  The only caveat is that the system appears to be splitting so more time is needed to determine its precip potential.

 

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