Over the next 5 days…..

Northern hemispheric pattern is highlighted by two major blocks. One near Greenland that is progressive. This assisted in a major cold wave over parts of Europe the past several days with fridged air and sever cold over Poland and other nearby areas. This Block is progressive.

The other developing Block in the mean (day +5) is located near the Western Aleutians with a corresponding long wave trof redeveloping in the Gulf of AK at about 140West. The amplifying upstream ridge will once again import cold arctic air from Eastern Asia via the Bering Sea, and fill the trof with it. As the Trof continues to reload with short waves…..This may eventually set the stage for a major wet storm through the Pacific Northwest by about the middle of next week (9th) as cold arctic air phases with southern stream energy WNW of Kauai. The further north you go, the wetter it will be. As of this time….The southern and south central west coast should be protected by upper ridging. 

In the meantime, our weather is still effected by a pattern that is not as amplified with an upper trof that will get kicked in Sunday night. The weekend weather will be unsettled with little snowfall for the high country until Sunday and into Monday with the trofs passage. Snow levels will range from 6500 to 8000 feet. Mammoth Mountain may get up to 15 to 24 inches in the Sunday through Monday period with the town much less. According to the new 12z WRF, prime time will be 06z Monday through 12Z Monday. Expect periods of gusty winds most of the weekend with highs in the 40s then 30s Sunday and Monday. Lows will return to the teens by Monday AM.

Longer Range:   There was some suggestion this morning by the opperational GFS…..that the upper jet would move south again into Central California by about the 15th or 16th of December for a stormy period for the Central Sierra. The change in patter is suggested by a progression of the long wave ridge to 160W…..There is also some support for that progression in the MJO week 2 model.

Reference Glossary of Weather Terms