Archive for February, 2015
Saturday February 28, 2015
Posted at 10:59 am by Howard
Sunday AM (24 hour) Update:
Although yesterday afternoon’s south push of deformation never materialized enough to bring Mammoth Lakes any snowfall…..Lee Side Upslope did occur over night where Mono Lake effect brought several inches to the Lee Vining area. Upslope precip will occur today and into the afternoon where a few more inches is certainly possible. The original forecast of 6 to 12 inches over Mammoth Mt has been reached on the lower end of the QPF with Mammoth Mt reporting 6 to 8 inches yesterday AM. However, we still have another 12 to 36 hours to provide additional light snowfall accumulations. This upslope will be light today and it may take the whole day to squeeze out another inch or three over the upper elevations. The Shear Lobe coming down the coast Monday Afternoon may effect just the interior Valley of CA or possibly add an inch or two of snowfall depending upon where any convection sets up in the cold unstable air aloft. Either way it will not be a big deal. CRFC gives Yosemite .36 through Monday afternoon. Some of that will be west side precip. However the Dweebs still think that Mammoth is still in about 1 to 3 inches over the next 24 to 36 hours between 4:00AM Sunday and Monday.
We ridge up the 2nd half of the 1st week of March, then another period of precipitation is possible beginning about the 10th of March.
It is interesting to note that out west this winter, the feelings are global warming in control……..However in the east, the next Ice Age is upon them with all time records of Cold and over 1000s of miles including Canada….
It certainly has been a winter of Climatic Extreme’s across the CONUS and eastern Canada.
Current storm working our a bit better than expected as a shear lobe will reload the current system early next week… Up on the snow plot, 6 inches of snow has fallen at the Main Lodge with .50 inches of water. That is a ratio of 12:1. That’s real nice for carving!!!! More on the way…..
Yesterday afternoon and last night:
During the afternoon and evening, the upper jet slipped south. The Vorticity field was elongated in Channeled flow and so we did not get the benefit from strong UVM in the warm sector. However, enough RH within the system combined with directional speed convergence on the west side with the sierra’s topo provided 6 to 8 inches mostly over the crest while just east of the crest like the Village, 4 inches fell, and by the time the air mass traveled over the Town of Mammoth only an inch or two accumulated. Obviously an absence of strong UVM. It was mostly strong speed directional convergence benefiting the west side up to the crest and a mile or two east…..
What’s next……for Saturday.. A break in the mid to late morning hours for our area. There is an area of deformation to our north at 700MB and the upper low at 500mb is to our north. That will all be sliding south this afternoon. The Deformation Axis will pass through Mono County between 21Z and 00Z today. Snowfall rates will pick up this afternoon. So a lot more snow expected later today. By 03Z Sunday, (7:00 PM Saturday night) the deformation axis will be well south down over the Southern Sierra benefiting Bishop South.
Tonight: The flow at 700MB 10,000 feet will veer Northeasterly….. At 700MB Directional speed convergence will develop along the Sierra Eastern Slopes of Mono County. The RH at 700MB will be 80%-90% and so upslope snowfall will develop by mid evening and continue into tonight and possibly into the mid morning hours. This all according to this mornings 12Z Saturday’s NAM model. By 18Z Sunday, the upslope weakens with just isolated showers expected over the higher elevations. There will be a shear lobe dropping down the coast Monday. There will be plenty of moisture in our air mass through Tuesday AM. We’ll have to watch the convective parameter’s to see if the air mass becomes more unstable for convective snow showers Monday afternoon. The NE quad of the upper low may favor Mammoth Monday PM…..with the chance of more snowfall accumulation….
There looks to be a dry period mid week through the next weekend with a warming trend…… The next pacific storm looks to be a good 10 days away…….
Dr Howard and the Dweebs……………………..:-)
Another Cold Storm is headed our way with good possibilities of at least another 6 to 12 inches over the Upper Elevations…..Friday through Saturday Night….Then Inside slider type system Monday Night and Tuesday adding to snowpack……
Thursday February 26, 2015
Posted at 8:42 am by Howard
One again snowfall amounts are expected in the 6 to 12 inch range with this next chilly Gulf of AK storm. The Maverick in this type of pattern is how and where the upper low spins up at 700MB and thus where the area of deformation sets up and how long it remains over a particular area and if that area favors Southern Mono County. That will be the key to the higher amounts. At the least, we can expect a good 6 inches up on Mammoth Mt and if the area of surface convergence sets up near Southern Mono County or begins to the north of us and slides south, we could see the amount of a foot or better over the upper elevations. Snow fall amounts in the cold air will be at a higher than normal ratio to water, just like the last system. However, not to the degree to call for a Platinum Powder Alert. 500MB temps are forecasted to be about -28C and 700MB temps about -10C, this will definitely bring snow to water ratios to possibly 11 or 12:1, but it is doubtful it would be cold enough in the Dendritic Growth zone for ratios equal to or >15:1….. So light and dry powder yes, A blast to easily cut through, but not Eastern Sierra Platinum…..
Dr Howard and the Dweebs………………………….:-)
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…………………….:-)