More rippen and tearing for the weather system coming in Wednesday…..Weather turning much colder in the days ahead…..”Is Another Atmospheric River event headed for Ca again??
Tuesday December 11, 2012
Posted at 8:25 am by Howard
Because of the critical wave length of the long wave features; both upstream over the eastern pacific and down stream across the CONUS, the upcoming short wave coming into California, will split off shore…with a significant amount of energy driving south down the coast. What is critical for the Central Sierra is how close will the system get to the coast as it tracks southeast….And how much upslope will Mammoth get.
The results of the wavelength will cause the storm to split, and thus:
1. Force a lot of the precipitation over the Northern Sierra which is a change from yesterdays thinking.
2. Cause the weakening of the cold front as it moves south through Mono County.
3. Cause a closed low to form over Central Ca at 700mb which forces quite a snow storm Wednesday night and Thursday AM in its NE quad for Northwestern Nye County, Nevada!
4. At 300mb, the RT Rear entry region of the upper jet favors Southern Ca. and Northern Baja/NE to AZ and Southern NV. The upper jet actually couples with the subtropical jet for a good shot of precip for NW Mex.
The Dweebs feel that light amounts is the way to play it for now, in the Mammoth Area with .3 to .4 inches of precip for the crest. So we are looking at a system that will bring 1 to 3 inches in town Wednesday from the weakening front and a bit better amounts with the 700mb low Wednesday night for about another 3 to 4 inches. In this type of system, the upper elevations may get not much more than the Village. And….this is the kind of storm that may not give us much of anything. so if we do not get much more a a few inches do not be too surprised. The good news is that what ever we get will be the cold powdery snow that we like!
Because of changes in the long wave pattern and retrogression….the Dweebs are becoming more disenchanted with the Sunday storm. So although officially…the NWS is expecting more snowfall…the current model runs are doing a lot of Poo-Pooing on amounts……A consensus now between the 12z EC and the GFS has the Sunday/Night system an inside slider.
Will update on this tomorrow…….We may end up with even less then the Wednesday/NGT storm.
The Dweebs feel that once retrogression is underway again, and the wave length adjusts over California, we may get into a wetter pattern that will favor the Central Sierra as well as the Northern Sierra. However that may take until next week sometime. In the meanwhile, splitting systems will turn it colder than normal beginning Thursday and on into next week.
Just a Heads up….
The GFS week 2, the last three runs has been touting a significant split in the energy of the polar jet, ahead of another blocking high forming in the Central Pacific toward Christmas.. There is “a suggestion” of possibly another AR event, similar to the one that brought so much rain to Northern Ca about a week to 10 days ago. Given that it is later in the season, I would suspect that the upper low will be colder than the last one that developed in the Gulf. Or, the southern stream may be stronger. The effects for Ca depend upon whether the block is more Meridel…. or will it morph into a blocking high that cuts off over AK?..with the resulting river “AR” headed into the Pacific Northwest. In that this pattern has already set up once for the west coast this fall, it is possible that it may repeat in one form or another. Additionally, in that the AO is negative; waters are slightly above normal along the west coast and that the PDO is slightly positive; and that ENSO is slightly warmer then normal; all these indicators give AR events a “slightly higher” bias from an air-sea coupling point of view.
The point is, that although this is “not” a forecast of another “AR” event for the west coast…..it is certainly worth watching to see how the models develop this new weather type over the next two weeks…….
Dr Howard and the Dweebs……………………….:-)