Sunday, January 26, 2014
The uncertainty displayed in the numerical model guidance this past week is resolving itself as Pacific energy is forecast to undercut the persistent west coast ridge. This is the first time this season the polar jet stream is finally forecast to carry seasonably warm and very moist air into the west coast, bringing snow to the drought-plagued ski resorts located there and bringing a Pacific storm track into the Great Basin and Rockies.
Before this new regime takes hold, a weak but cold storm currently to our north will bring clouds to the area later today and light snow beginning around midnight. The westward extent of this storm is still bouncing around in the models, but I would expect snow all day on the hill tomorrow with 1-2” by Monday morning and possibly 3-6” by Tuesday morning, with most of that occurring by midnight Monday.
A break on Tuesday before the undercutting jet stream slams into the northwestern coast by late Tuesday. Similar to tonight, another cold wave drops down the west side of the Hudson Bay vortex and phases with a wave in the undercutting polar jet stream that is forecast to contain a fair bit of subtropical moisture. The end result is the polar jet stream is pushed southward to California and our flow backs from the north to the west, warming temperatures and increasing winds.
Snow is currently forecast to begin on Wednesday, and the interaction of the polar jet stream with the cold waves rotating around the Hudson Bay vortex will keep our weather snowy through the week. Additionally, the polar jet stream is forecast to buckle by the weekend, dropping a storm into southern California by the weekend and backing our flow further to the southwest. Snows are likely to continue through the weekend as this very dynamic weather pattern evolves.
With so many interacting pieces, predicting snow amounts is difficult at this time, but an extended period of moderate to heavy snows with periods of high winds is likely starting Wednesday and lasting through the weekend.