Archive for December, 2012

One Last shot of Snow and Rain from the Subtropical Jet Today then Pattern Change this Weekend leading to a Cool and Dry weekend and beyond…..

The last in the series of subtropical jet related systems to effect Mono County will arrive later today. Gusty winds have been blowing most of the night and will continue to do so throughout the day.  The snow level will be about 8700 today down to 8300 tonight. Over the upper elevations,A few inches of snow will fall by Midnight tonight.

The next pattern change occurs Friday as the current cold low in the Gulf of AK weakens and ejects ESEward into the pacific NW while a full latitude ridge builds northward about 140W and takes its place by Saturday. So the change that is in the offering is that we get rid of the Subtropical jet and mild WSW flow to one of which comes from the extreme northwest pacific which will have continental air mixed in with it. For the Sierra, this is a drier pattern with impulses next week dropping into the Great Basin via the Pacific NW. (There is always a chance of a few snow showers if an impulse get far enough west to effect us.)  Expect Arctic Air dropping south over eastern Washington state eastward through Montana….making for a storm track NNW/SSE over the Rockies with light snowfall favoring the Central Rockies like Colorado Saturday afternoon/night.

Drier continental air in December usually makes for much colder mornings here in Mammoth, with daytime temps between normal and below normal. Highs will cool into the 30s by weeks end. Nights in the upper teens and low 20s. Temperature inversions may set up with some temps over colder valleys like Bridgeport/Bodie dipping down into the single digits next week.   As a surface high drops SSE from BC, Canada into the northern Great Basin, Off-Shore flow develops Sunday for California. Southern Ca WX looks marvelous Sunday…..A Day at Disneyland?

Longer Range:

So far the action next week stays over the Rockies then pushes even further east to the Northern Plains with the Northern Plains states experiencing there first real shot of Arctic Air this Fall…. However…more importantly…..it will be interesting to see where the Arctic air will go afterwards….

Will the -AO team up with the NAO by it too going strongly negative. Will a high latitude block set up over Greenland and a deep Hudson Bay Low, giving all the Weather Weenies over New England a Solstice Treat? Or…..will the main PV descend over AK with retrogression of the eastern pacific high, providing a good old fashion Sierra Snow storm the days following the Solstice? Time will tell……………………The Dweebs got you covered……

 

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

West Coast Atmospheric River Winds Down this Week Lending to Inside Slider Pattern by Sunday….Further Retrogression Next Week Lends to Possible Cold Snowy Pattern….

Tuesday Am Update:

 

Remains of last short wave will move through as mostly warm advection precip. IE Rain up to 10K. About .4 to .5 QPF is in the picture for the crest.

Wednesday night’s snow level drops to about 8500…however system is mostly through.   Inside slider pattern this weekend for chance of snow showers Saturday night into Sunday. Breezy cooler….just what we need!!!

Highs the next few day in the upper 40s…..lows above freezing…..Then teens by this weekend…..

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Nice Wet Storm!!!  Mammoth Mountain has great set up for the Christmas/New Year Holidays!!!!!!!

5.5 foot storm total at the main lodge with a lot more over the upper elevations……  Storm total 10.24 inches of Water!!!!

If you were going to design a winters snow pack and Summers runoff you would not do it any differently than what mother nature has done naturally this Fall.  The current set up of a rich sierra cement base with high water content, will get compressed throughout the remainder of the winter/spring and will last much longer for the Summer of 2013…..”Great for the Water Supplies”

The weather for the upcoming week with be highlighted by a continuation of the “AR” pattern, however shifted much further north. Only extreme Northern Ca. northward will be affect by heavy precipitation. We will get clipped by another period of warm advection precipitation about Wednesday from the last in the series….No doubt it will be accompanied by high snow levels…   Expect lots of cloudiness over the next several days.

The GFS and more recently the ECMWF models are showing the eastern pacific upper high anomaly amplifying and progressing to 140west by the end of this week. That is an inside slider location this time of the year and so expect cold NNW winds to develop with snow showers and much colder weather “About Sunday” a week away…..  The GFS thereafter shows retrogression in the long wave.  If that verifies, expect a series of short wave trofs that head our way from the Bering Sea.  Short wave trofs with over water trajectory  along a track on the back side of the long wave, will ensure higher snow to water ratios…..

 

More later…………………………..

 

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

 

 

 

Strong Cold Front on the way and Accelerating SE-ward…..Cooling is expected by Noon with heavy snowfall expected above 8000 feet today….Winter Storm Warning in effect for elevations above 8000ft this afternoon….

3:30pm Update:

Weather Fronts Through….Snowshowers Now….

Time for clean up….

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Sunday 10:00am:

Heaviest precipitation “to begin” between 10:00AM and 12:00 Noon Sunday….

Main Lodge at 9:00am…..Rain/Rain Snow Mix……  At 10:30 all snow at Main Lodge…”Freezing Level
9800 will lower to 9500 by about 10:00am then down to 9,000 ft by 4:00pm……Snow Level to Fall to 8000 by Noon then 7000 by 3:00pm.  ALL Snow at/above McCoy Station……>>>> No micro physical processes at work to promote snow level lower then expected. Column not saturated from either Dendritic Crystal Growth zone to 7000ft….
Dry slot at 750mb.  SEE: http://weather.rap.ucar.edu/upper/oak.gif

At 10:00am it was 36 degrees at 8200ft.  Mostly rain and rain-snow mix at the Main Lodge and Snow at McCoy Station.  The outlook for today is for falling temperatures the remainder of the morning and through the afternoon.  The snow level will be falling to 8000ft by about 12:00 Noon and to 7,000ft by 4:00pm.

The National Weather Service has hoisted a Winter Storm Warning above 8000 for this afternoon until 7:00pm this evening for hazardous driving conditions in the Towns of Mammoth and June Lake as well as the higher passes of 395 through out Mono County such as Conway Summit and Dead Man Summit just north of the Crest View Station.  Expect between 10 and 14 inches above 8000 ft and 4 to 8 inches above 7000ft by 7:00pm tonight.

LONG RANGE OUTLOOK:

Looking out the next Few Weeks…..

1. The odds favor Dry Weather between the 9th and the 15th.

2. The odds favor more snowfall during the period 16th and the 22nd of Dec.

3. The odds favor more snowfall during the period the 23rd and the 29th of Dec.

 

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