Ensemble members rapidly increasing trend toward wet pattern for California by Mid Month…Subtropical tap/connection very possible with set up….
Friday February 4, 2011
Posted at 10:00 am by Howard
Beautiful weekend shaping up…still gusty NNE winds over the sierra crest expected. Expect highs in the upper 40s and low 50s this weekend with lows in the teens and 20s. Light breezes will be the rule for most areas excluding the sierra crest.
Next inside slider is headed for the Great basin Tuesday. Winds will pick up again with colder weather Tuesday into Wednesday. Highs will return back into the 30s. The new 12z GFS has the system digging a bit further west now and so a dry back door cold front is expected with strong north wind for the Owens Valley Tuesday afternoon/night. The weather looks milder Thursday into Friday. Expect increasing wind over the upper elevations that next weekend.
Over the past two days there has been a rapid increase of ensemble members showing a pattern change for the central west coast to a stormy one. As usual…the timing is different between global model’s ECMWF and GFS. The ECMWF is faster with the change bringing snow to the Mammoth high country as early as the following weekend with the GFS holding it off until the following Monday the 14th. Using the timing of Cylkes western pacific surface bomb 96 hour rule, the first surface system moves off Japan and spins up the night of the 10th…..so it energy should propagate through the west coast the night of the 14th (Monday). Then another stronger rapidly intensifying surface system moves off Japan the night of the 13th, and so its energy (propagate) would be expected to come through the west coast the night of the 17th based upon this mornings data snap shot.
The good news is that the upper ridge at this time is forecasted to develop a REX Block signature and is expected to locate between 170w to 180 west. The tropical upper low that is part of the REX block is located about 28N and just east of the dateline. Strong convergence with the easterlies is hinted at, with a train of thunderstorms developing north of Hawaii the night of the 11th into the 12th. This tropical/subtropical moisture may get entrained into the first system headed for the Pacific northwest. As the polar jet slides south, the fetch may follow into California the week of the 14th.
Because of where the upper long wave ridge is setting up….This pattern is good for the development of tropical moisture which may entrain subtropical moisture and involve the confluence of both the polar and subtropical jets into California.
The upper ridge is still in a favorable position as late as 384 hours out and so an active pattern may continue once started, into the 3rd week of February.
Note: We still have a long way to go time wise, and thus a lot can happen between today and next week. The Dweebs will keep good thoughts and hope that the models still show that a good dumping is in store for our area by mid month.
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.