Mid Latitude System Lurking Toward The Middle of Next Week!

Just a quick update for the longer range……..

Both the 12z GFS and the 00z Wednesday ECMWF have a subtropical system coming into northern and Central Ca about Tuesday. The GFS has it a little earlier with the main punch further north. The ECMWF has a good part of it effecting Central Ca. This is a fairly warm system with high snow levels about 8000 to 9000 feet.  The EC is pretty wet with it Tuesday night/Wednesday a week away. It may be warm advection precip.

This system  is currently approaching north of Kauai and is part of the pattern of concern that the Dweebs discussed over the weekend. The fact of the matter is….The Greenland block is still going to force a pattern change over the next week with the ultimate result a cut off upper high over Western AK  and an upper low to the south of it, north of the Hawaiian Islands. There is short wave activity that will come out of the westerlies associated with the big vortex north of Korea.  By this Saturday afternoon, the ECMWF has a closed anticyclone centered over the Aleutians with a Subtropical closed low directly south/north of Hawaii at 30 N. This completes sort of a REX block with two distinct streams with the split between Hawaii and the dateline. 

By Sunday night, the remains of the Greenland block merges with the cutoff high over AK, while a strong short wave coming out of the Asian/Siberian Vortex boots the current closed low north of Hawaii toward California.  The short wave thus replaces the current system north of Hawaii as it too becomes cut off. The big question arises on whether or not the subtropical system makes it into California, as it has to fight a subtropical ridge between the mainland and Hawaii. The ECMWF has a pretty wet storm for California Tuesday the 11th of January with 90% HR at 700MB. 

see: http://www.met.sjsu.edu/weather/models/ecmwf-00/ec_relh700-ani.html 

As a Note: The GFS is not nearly as wet.

There will be subsequent short waves coming out of that mid latitude weakness north of Hawaii later next week. However, the cut off upper high is supposed to retrograde, thus allowing heights build over the Eastern Pacific again, pushing the moisture further north……….stay tuned.  The Dweebs got you covered!


PS.

Please no 12 foot Rumors…..It is too soon….

The Dweeber……………………..:-)


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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.

High Pressure Aloft Builds Into The Golden State For Some Spectacular Weather….Warmer Temps On The Way..then Breezy and Cooler Saturday and Sunday!

Latest short term guidance continues the trend of higher heights over California. Strong inversions aided by clearing skies and radiational cooling over night sent low temps as cold as -17F at the Mammoth AP at 7:00am. That was more than 30 degree colder than the previous morning. Thus….the inversion was definitely stronger this morning over yesterday. Expect high temps throughout the high country valleys to remain much colder then elevation 8000. Possibly only in the teens today at the Mammoth AP.

Heights will rise into the mid 570s by early Thursday morning with surface pressures reaching 1030MB. No doubt it will be another very cold night tonight in those same high elevation valleys.

The next change in the pattern takes place this weekend as an approaching short wave flattens the upper ridge that is currently building over the state. That system will act as a kicker and boot the current cut off low now west of LA drifting southward……then east across northern Baja as a short wave ridge comes through Central California. The storm itself is an inside slider type system with no over water trajectory at our latitude and is headed toward the Rockies. I expect breezy to windy weather Saturday into Sunday with cooling the same period. There may be some snow showers along the eastern slopes Saturday night or Sunday.  

Longer Range:   The trend of the long range is for an increase of the amplitude of the long wave upper ridge about 130west. This is a dry pattern for the Eastern Sierra.  Cold Arctic Air will invade the Rockies and Midwest then eastward with some spilling into the Great Basin. Most of it should stay east of Mammoth.  So temps next week could be a bit below normal for January. Easterly wind over the upper elevations is a possibility.

The Dweebs are now looking at an extended period of dry weather for the high country for a week….possibly two.  All longer range models have now  for the time being, given up on the idea of a moist westerly flow into California.  If that should change….I will definitely give you all plenty of notice. Additionally, there is always the possibility that one of these fridged air masses could drop down over the far west for a “Mammoth Cold Wave” about mid month….


PS.

No Update Wednesday…..I will update late Thursday if I can…..

Enjoy the fair weather and all the great snow!!!!!


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.

2nd Half Of Snow Forecast Busted For The High Country….Nice Break In The Weather Coming Up Beginning Tuesday

What a Season!  Mammoth Mt is reporting 311 inches of fallen snow for the ski season of 2010/2011! The annual average is 343, so were less then 3 feet away from a normal ski seasons worth of snowfall and its only January 3rd!

The Past Storm:

First half the forecast was on the money…the 2nd half a bust!

Systems that are not forecasted to traverse across the Sierra are the ones that are most difficult to forecast snow fall wise along the Eastern slopes of the Sierra.  Mammoth Mt did pick up between 1 and 2 feet with the town 6 inches + between the 1st & 2nd.  The snowfall was primarily warm advection  snowfall by which relatively warmer air over riding a colder air mass was then lifted to create snowfall. The big active band of heavy precip did not make it over the crest yesterday!

The pattern over the next 5 days is highlighted by the redevelopment of the Greenland Block…(-NAO)

and…….

1.  An upper low off the Southern Ca Coast becoming cut off from the westerlies as an upper high builds over the top of it into California.

2.  An easterly flow will be the dominate pattern here in the Mammoth area beginning later tomorrow Tuesday insuring fair but cold weather until about Thursday/Friday when  HT 500 heights come up into the 570s and we loose our chilly easterly flow. We then may get up into the low 40s by Friday.  The off shore upper cut off gets ejected eastward Saturday and will become a major player in the weather across the south-southeastern CONUS. (ice storm?)

3.  Model skill seems to be decent into the weekend when some sort of inside slider drops into the Great Basin Sunday. As a result, no doubt there will be cooling Sunday into the early part of the following week. Possibly some snow showers as well.

THEN:

4. Big questions arrives for the following week with how the big Greenland Block which becomes more of an north central Canadian block will effect the upstream high latitude pattern.  The long range models are all over the place with the evolution of the Alaskan Block and how the Greenland/Canadian Block relates to it. This mornings 12z GFS week two maps are so out to lunch its pitiful. The ECMWF still suggest the possibility of  a wet lower latitude active pattern which would effect California sometime between the 10th and the 15th. This is certainly pushed back several days from from the models earlier forecasts…However,  it is still there and a possibility.


More Later……………………….:-)


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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.