Mammoth Mt Reports 9 to 12 inches of fresh snowfall….The Dweebs report 8 Inches in the Village……Main area of precipitation is now well south of the Central Sierra….Next snow producing system begins about Friday…..It looks like a windy bugger…..
Monday February 23, 2015
Posted at 1:29 pm by Howard
The Dweebs have a very strong interest in the pattern for the month of March, as if we are going to get a good storm….it should begin to show up within the next week to 10 days…. While the long range models are still touting retrogression of the eastern pacific ridge and although outlook forecasters are still touting drier than normal weather for CA the next 6 to 10 and 8 to 14 day periods, not all the Dweebs are totally convinced. One reason why is that both ECMWF and GFS are at odds with what the MJO is going to do. Although it is weak, One of these models has to get it right, as just a blend between the two won’t work.
I did have a look at the deterministic run of the 12z GFS this AM and it still shows retrogression over the next two weeks. That would be great! However, the fly in the ointment is a REX Block that is trying to form out over the mid pacific. This will tend to keep a dry NW flow and dry pattern for CA later next week and into the following. However, the 12z Wed Ensemble Control has a bit different opinion.. It too try’s to set up a REX by 7th of March but the REX is negative tilt! So that the Upper low is not as trapped underneath the Central PAC upper ridge. Although the main 500mb Height anomaly backs to between Hawaii and the Dateline week 2, the cut off underneath does not allow the usual wave length set up for a storm track that benefits CA. However, with time and with further retrogression that will change as the upper low in the subtropics get kicked out. The EC Control from last night was much more amorphous, and although there are signs of retrogression as well, more time will be needed to identify a trend in that model..
However, the new 12z Wednesday deterministic ECMWF just finished running…..it shows a much more defined pattern with retrogression “and” amplification. No surprise with a deterministic model run.
In the shorter term….the new EC deterministic takes the Monday Ngt system that up until now is/was an inside slider for Monday night and Tuesday, down the west side of the Sierra for potentially more snowfall!
STAY TUNED…….in Meteorology, there is rarely a dull moment!
After one of the chilliest mornings since early January; 9 degrees (At the Village), the freezing level will take a jump today from 6,200 to 11,200 within 12 hours! That’s a lot of warming aloft in a short period of time. So our high temps in Mammoth will go from the upper 20s of yesterday to the upper 40s today. Expect some residual warming tomorrow with highs in the low 50 and again Thursday. The vast majority of the medium range models take that next significant short wave down over the interior of CA just west of the Sierra as the upper ridge amps out at about 140W to 142W . The upper flow will be more northwesterly and so little in the way of orographics will come to play for Fridays precipitation. CRFC QPF has around .6 through the event which will be more Friday Night and Saturday. The freezing level again drops to the upper 4000 foot range by Saturday AM so the system is very similar in temperatures to the last system. IE Cold dry powdery type snow. The upper low that spins up may not linger as long as the last system, however, there will be more moisture to work with as the upper jet is somewhat over water. The big question remains…will a deformation zone set up again like the last system….and if so, where will it set up? The last upper low had the deformation zone axis a little south of Mammoth where it shifted further south yesterday. We definitely benefited from that. Early indications are, a deformation zone (Surface convergence Feature) will set up over Northern Mono County eastward then shifts south. More on this feature later in the week as it is way too early to be getting excited about the location of this feature. Additionally, it should be mentioned, in that it is the end of February and early March, a cold system like this one has pretty good convective potential, so that will need to be considered as well for snowfall.
In the meantime, there is a weak short wave that will bring mainly moderate wind over the upper elevations Tonight and Wednesday along with some clouds and rising temps through Thursday. The following system for Friday, has the dreaded NW jet for a period of upper convergence over Mammoth for windy conditions later Thursday into Friday. All that before the main area of (UVM) upward vertical motion shifts south Friday night into Saturday AM.
Dr Howard and the Dweebs…………………………….:-)
The Active Portion of the upper cut off low is now well south of our area. So partly to mostly cloudy sky’s will lead to over night clearing. Since the system is forecasted to exit into AZ tonight…No Wrap around precp is expected. Day time highs will climb into the 40s Tuesday and mid to upper 40s Wednesday and Thursday. It will become quite breezy Thursday as the next upstream systems approached with its NNW upper jet. Windy weather is likely to occur Thursday night into Friday with a NW jet. The Next storm looks to bring similar amounts as the last……Again it is all dependent upon how much over water trajectory the upper jet has and how the upper jet comes at us. A NW upper jet is not ideal for heavy snowfall. This next system looks better for the Southern Sierra than the Central and Northern Sierra as the upper jet begins to back more west/SW there. It will be another cold storm with high Snow to Water Ratios…. If by chance the ridge retrogrades more west….it would be a different scenario…. Longer range and interseasonal models still continue the idea of further retrogression later in March.. However, both the 6 to 10 and 8 to 14 day outlooks have gone dry again….
Dr Howard and the Dweebs…………………….:-)