Archive for February, 2011

Arctic Air Continues to Plunge/Modify down the West Coast….While Heavy Snows Pound the Central Sierra

UPDATED:11:00am

Full on winter storm in progress at this time as the southward push of the strong closed low off the Oregon coast  continues into Northern California throughout today. The onshore flow has been strengthening this morning and Mammoth Mountain has picked up well over a foot as of 8:00am. The latest satellite motion shows a nice tap (.8-pwa)of moisture from the mid pacific that seems to be favoring the southern and south-central sierra.  This will support heavy amounts to accumulate throughout the day today and tonight. The latest update from CRFC is showing another 1.8 inches of QPF  for our area by morning. By Saturday…the strong height falls that are currently occurring offshore will shift east into Southern California and bring heavy amounts of snowfall to your local mountains. All in all considering how cold this storm is…..UVM and  moisture,  amounts over Mammoth Mountain will easily be in the 3.5 foot to 4.5 foot range over the powder fields of the upper mountain by Saturday.

Further Discussion…….

A strong cold front is pushing south across the Sacramento Valley. At the same time, a developing lee side surface low is slowing the progress of the front. Without this development the front would have been already south of Tahoe by now limiting the amount of snowfall the Mammoth area would  receive. So, in retrospect, the wetter models were better, especially once the moisture moved eastward reaching the coast and the right rear entry region of the upper jet set up over the northern part of the state. All considered, this system is making the most of the current moisture influx.

Looking ahead today. The cold front will slowly drop south today toward Central Ca. However, over Northern Nevada where the Lee side development is expected,  the front may hang up a bit longer delaying the front through Mono County until very late afternoon or evening. Surface convergence is likely to persist over Eastern California into the night for another foot of snowfall beyond this afternoon. 

Pacific Sat view:

1. Nice lingering Kona low continues to draw up moisture from the tropics into the subtropics. This moisture will become a player later next week……

2. Current upper anti-cyclone at 50 north/150west is positive tilt and will aid with the short wave coming south to push the current cold off shore system southward.

3.  ((((“More importantly”))))…a strengthening low latitude subtropical upper jet will work into the western pacific in the days to come strengthening.  This will have the effect in developing a tremendous amount of amplification in the central pacific upper ridge, building it into the Bering Sea. There is the suggestion of the confluence of a strong low latitude subtropical jet with the Polar in early March.  One break through of the westerlies may occur about the 28th of February as a cold upper trof from the Gulf digs southwest to meet up with it, the second half of next week. At the moment the emphasises is for Northern Ca for the heaviest Precip, however this is a developing situation and subject to change. What is happening here is the “potential” for a very wet pattern for the west coast over time. 



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


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Reference Glossary of Weather Terms
Disclaimer: I have been a hobbyist meteorologist for over 30 years here in the Mammoth area and I do this for my personal enjoyment. The National Weather Service saves lives every day . . . I do not. When making important planning decisions please use information provided by the National Weather Service as they are the most knowledgeable and accurate information source available today.

Heavy Snows Pound The Eastern Sierra with 2.5 to 4.5 feet expected over all….Snow Machine just getting started with Miracle March a Possibility

Updating………

 

 

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Reference Glossary of Weather Terms
Disclaimer: I have been a hobbyist meteorologist for over 30 years here in the Mammoth area and I do this for my personal enjoyment. The National Weather Service saves lives every day . . . I do not. When making important planning decisions please use information provided by the National Weather Service as they are the most knowledgeable and accurate information source available today.

Arctic Born Storm to test forecasters abilities along the coastal sections of the Bay Area northward as Snow Levels may drop below 1000 feet Friday…..Up in the Sierra, this will be a powder event with very cold temps Friday night into Saturday.

Sierra Forcasters will have a somewhat easier time with the forecasts the next few days as the precipitation that falls over the Mono County Area Friday and Saturday will certainly be all snow! Questions still remain about how much snow will fall as the system  itself  is currently pretty dry but will pick up moisture as it develops off shore. The QPF from California Rivers Forecast Center paints about an inch and a half over the crest by Saturday AM, giving the upper elevations a good 2 to 3 feet. This is considering the cold nature of the storm and the potential ratio of snow to water….. 20:1 to 25:1.  The big question remains about the possibility that this system may tap some deeper moisture from the central pacific Friday that would help boost QPF totals….hence this is still a very much developing storm that may prove to be a bigger precip producer for the high country than what the models are currently showing. Of course, if it does tap central pacific moisture, that may moisten the system up a bit with the ratios not quite as high as we currently expect.


What We Know:

1. A very deep upper low will form off the coast of Vancouver by Thursday Night

2.  This upper trof will then sag southward just off the coast of the Columbia River by early Thursday and continue to shift southward down the west coast through Saturday Morning. Deep layered onshore flow will exist in the mid and lower levels for a prolonged period of time….. and so what we will experience is really one big ocean type Lake Effect into the sierra beginning Thursday night into Friday afternoon. If the central pacific moisture gets tapped, that would be the bonus.  So again….A combination of onshore flow, UVM, orographics and strong upper jet dynamics will keep this a major storm to contend with. At the moment, a good 2 to 3 feet of snow is certainly possible by Saturday morning. Will update on the estimated amount of snowfall Thursday morning.

3. The other big issue here is the Arctic air dropping in over California from the north instead of back dooring us from the northeast. The new 12z WRF has -18C over Mammoth Mountain at 10,000 feet Saturday mid morning. That is -4 F. and temps in the town of Mammoth will probable be in the low single digits Saturday morning. Any wind at all will create a significant wind chill factor Saturday. Up slope conditions may develop Saturday afternoon into the evening.

4. The best part of this storm is that it is pure Western Canadian Born. In perspective, it is rare that Mammoth gets the potential for large amounts of snow at ratios of 20:1 to 25:1. Saturday for those that want to experience deep cold dry powder will want to have the right warmth for the elements. And  to experience the possibility,  of true Canadian type powder! 


Dr Howard and the Dweebs……………………….:-)



————————————————-
Reference Glossary of Weather Terms
Disclaimer: I have been a hobbyist meteorologist for over 30 years here in the Mammoth area and I do this for my personal enjoyment. The National Weather Service saves lives every day . . . I do not. When making important planning decisions please use information provided by the National Weather Service as they are the most knowledgeable and accurate information source available today.