Upper Trof now making its way through California with lighter breezes expected Thursday along with warmer temps…This weekend will be especially nice with highs in the 80s and little if any chance of rain…..Monsoonal Flow returns Sunday-Monday……
Wednesday July 23, 2014
Posted at 10:33 am by Howard
Currently, a weak upper low is west of Northern Baja reacting with the Continental High and Mammoth is in-between the two. This has spun up a weak 50 knot jet and is producing high clouds that is streaming through our area. This little feature will lift NE over Northern CA later today and tonight and RH will diminish at 300MB later today and tonight as this feature moves away. Tomorrow Saturday, the upper flow backs to the South later in the day and eventually SE by Sunday. This opens the door to increasing RH at 700MB (Monsoonal Flow) and so expect mid-level clouds to increase from the South later in the day Saturday with a lot more mid level moisture pushing into our area Saturday night and Sunday. It should remain dry Saturday with warmer temps because of the lack of high clouds. By Sunday, we may become over developed (Mostly Cloudy Early) and so any thunderstorms would be isolated. Further moistening will occur Sunday night into Monday and into Tuesday for a better chance of afternoon and evening TSRWS. There are a couple of VT centers that will lift through the sierra between Monday and Wednesday as well. By Friday the 1st…The upper flow begins to back to the SW and drier air begins to move back into our region. The Blues Fest will be Hot ! 😉
Quick Look at the new 12Z GFS 700 Temps….shows 15C isotherm over Mammoth during the late afternoon and Saturday afternoon. This is quite warm and will promote highs in the Mid 80s today and Saturday. 700MB moisture begins to increase later Saturday and into Sunday. 700 temps begin the fall off toward 10C by Sunday into the middle of next week. Temperatures do begin increasing again back up to 15C the following weekend. As far as the possibility of any remaining thunderstorms from mid week….it all depends upon the strength of the upper flow and its ability to flush the moisture out.
The Dweebs will take a good look at that next Wednesday……
Note: +15C at 700MB with drier conditions in July and no significant cloudiness, usually gives Mammoth highs in the mid 80s……+10C = mid to upper 70s
Dr Howard and the Dweebs…………………………………………………………………:-)
From Thursdays Discussion:
Upper trofing off shore has been weaker than most Summers and the Subtropical high has been more persistent in directing both moisture and dynamics into the Eastern Sierra. Currently…we are now being influenced by an Eastern Pacific Trof associated with a Closed Upper low over the pacific NW. This storm will actually bring snowfall to the upper elevations of Mt Rainier today. With the current dry fetch of SW flow over the Sierra, the usual process of getting rid of the Monsoon moisture and stabilizing the local Air Mass over Mammoth Lakes has taken place.
Stabilization will only last about 5 days though. This is what has been unusual this Summer. Usually it is the other way around with more of a persistent trof to the west of us, keeping our air mass drier and more stable. This Summer it is different, with more episodes of SE Flow and Dynamics. Why? Because of the stronger than normal long wave trof over the Great Lakes emanating from the PV east of Hudson Bay.
This is not the first episode of a system diving south out of Canada creating one of the coolest Summers in the Great Lakes region, south and SE. It is only this time that it’s origin is out of the North Pacific. Nevertheless, this is why it continues to be so hot in many areas of the Great Basin and the Monsoon more persistent further west. Long wave trofing in the east and a ridge in the west….. A familiar teleconnection? So this time, an upper low over Washington will lift NE to Alberta Canada tonight…then push east to Saskatchewan Canada Friday night, as it squashes the big 600DM upper ridge over Colorado. As the short wave shifts SE over North Dakota Saturday night, The short wave pushes on the eastern flank of the upper subtropical continental high, squeezing it westward after tilting it negative. This action forces the upper high to build negative tilt into Eastern Nevada by the end of the week and into Monday. This sets up the SSE flow of dynamics and monsoonal moisture from AZ, Sunday into Monday. At the moment the ECMWF is a bit more aggressive in its westward push of increasing heights than the GFS. A bias that seems a bit more accurate this Summer. As far as sensible weather…after a fair and warmer then normal weekend….expect an increasing threat of Thunderstorms over Eastern CA early next week. Whether this pattern is a major player in Mammoth’s weather is not known at this time. As usual, it depends upon where the direction of the little spokes of vorticity set up in relation to the sierra.
Inter seasonal tropical update:
The majority of dynamical model forecasts of the RMM index continue to indicate weak or incoherent MJO activity during the next two weeks. These include the GFS, Canadian, JMA and Taiwan Central Weather Bureau models. The ECMWF and CFS forecasts, however, indicate a more amplified, eastward propagating signal over the next few weeks. The propagation speed is somewhat fast and of generally only weak to moderate amplitude. This may be primarily in response to the somewhat slowly evolving Kelvin Wave. The MJO is unlikely to play a major role in anomalous tropical convection and highlighted impacts are principally based on the KW and ERW evolution, the tilt toward a warm ENSO base state and model guidance.
Fair dry weather returns to the high country this week with warm days and cool nights….The days get back into the low 80s by Thursday with further warming into the weekend…..It should be a dry week over all up untill Sunday….
Monday July 21, 2014
Posted at 11:21 pm by Howard
A dry southwest flow has begun the drying process here in Mammoth. Daytime convection has moved east, and outside of some high clouds and a few puffy Cu….we expect to remain rain free through Saturday. Locally breezy weather with an enhanced Zephyr is expected the next few days. Daytime highs will remain in the mid 70s through mid-week then warm into the 80s by Thursday and Friday. Next weekend and beyond will be unseasonably warm.
Longer range has the upper high fixed over the far desert SW through the 31st. The First weekend of August looks s bit breezy in the afternoon with the return of troughing off shore along with daytime highs returning to the upper 70s….
Dr Howard and the Dweebs…………………………:-)
Forecast Models continue to Back Peddel on moving out residual moisture and so moisture to be recycled on a daily bases untill best SW flow Develops By Middle of Next Week……
Saturday July 19, 2014
Posted at 7:13 am by Howard
Sunday AM Update
A line of thunderstorms have developed ahead of a vort center moving up the Owens Valley. The storms are likely to move into Mammoth Lakes shortly with rain, thunder, lighting and possible small hail. The impulse will shift north later in the morning through Mono County away from Mammoth after 10:15 am.
Scattered thunderstorms are possible through this evening then clearing later this evening. It will be partly cloudy Monday PM with only a slight chance of rain over Mono County then dry with a warming trend by mid week through Saturday. Next weekend will be very warm again with high in Mammoth in the 80s…
This has become one of the most persistent Thunderstorm patterns in years for the Eastern Sierra. After the initial push of south easterlies…..Mid and Upper level winds have been very light the past several days. Recent models runs continue to delay mid level drying, now until next Tuesday or Wednesday of next week. Thunderstorms will now likely develop here and there, seemingly at random the next 3 to 4 days…..
Latest Guidance shows light SE flow continuing to move out of AZ into SE CA, then up into most of California throughout the weekend. This will bring a reinforcing shot of mid level moisture to our region this afternoon. To add to the mix, there is a rather broad area of weak low pressure centered west of San Diego. It is being formed within a Coll, “in-between” the upper high to the East and another area of high pressure aloft to the WNW. This area of low pressure is forecasted to push a mid level wave into Southern California later this afternoon then northward up through Mono County tonight. It is possible that this will provide the lift for nocturnal storms over night throughout Mono County tonight. Campers should be aware of an elevated threat of rain tonight in the Sierra, after sunset.
Sunday looks like another day of thunder over Mono County, however, once again the models are trying to deepen an upper Trof from BC toward Oregon. Although the timing is up for question, the main idea is for this Trof to couple with the subtropical low to the SW of us and develop an upper Jet over Southern CA Sunday night which lifts north through our region by Monday Night. This should eventually put an end to our thunderstorm pattern with drying ushered in by the upper jet. Of course the upper jet may briefly create some lift itself through the process for Mono County Monday for a continuing threat of thunder that afternoon before it shifts north out of our area Tuesday into Wednesday.
Another heat wave looks likely to develop later next week as the Subtropical Continental high expands west again into California later Thursday into that next weekend. It will heat up later next week with 80s returning here in the high country and low 100s for the Bishop area. Then….SE flow and dynamic’s (Monsoon) returns over that weekend with more Mono County thunderstorms….As the process begins all over again!
Dr Howard and the Dweebs……………………………:-)