Upper low over Nevada to back wash some showers and thunder to the Eastern Sierra….it will be warm and dry this weekend…..1st in series of Fall Trofs to make there way to the Pacific NW by mid week…..Cooler possibly windy weather 2nd half of next week for Mammoth Lakes……
Wednesday September 11, 2013
Posted at 8:50 am by Howard
LI index is -.5 now with .7 PWAT
Convergence along sierra crest is evident with Cu popping.
Some chance of some showers is in order today.
Fair and Breezy Sunday
Saturday AM update:
Only change this morning is a little extra residual moisture around and plenty of sunshine. Looking at the SPC, there are no areas of Divergence/Convergence couplets regionally. Just a little extra sun and moisture today as PWATs are up from yesterdays convection. LI are in the plus range. It is going to take a lot of heating to pop a few showers.
Forecast is for isolated TSRW’s but that looks pretty scanty. Tomorrow will bring clear skies but breezy weather by afternoon. The forecast GFS Proggs are consistent in developing a long wave trof SE of the Gulf of AK and deepening the anomaly to -275DM west of Prince Rupert in the day+ 8 means. The EC is not as deep. The GFS also has good upstream amplification north of Hawaii. If the EC jumps on the GFS wagon…..get ready for lots of hype from the media!
As previously mentioned…this is worth keeping an eye on as around the 21st of September is the notorious “equinox storm”. A climo curiosity that seems, but not always….in the cards annually. One thing is given, it will be much cooler by next weekend………..Prost!
Dr Howard and the Dweebs……………………….:-)
Thursday AM Update:
No Surprises this morning…. two more days under the influence of the upper Nevada low for a slight chance of TSRWs then a fair weekend. Deep southerly moisture flow out of Mexico affecting the desert SW will shift east as large scale changes initiates stronger trofing in the Pacific NW. So the death blow to summer monsoon is coming soon…..
Long range GFS and GFSX has long wave trofing growing stronger in the pacific NW with eventual amplification upstream. Will keep an eye out for any TS activity in the western pacific as that can either Amp the down stream pattern or weaken it due to constructive or destructive phasing….
Equinox trof now in sight as we move from Summer to the fall……..first dusting may occur during the first week of Fall……..get ready to rake some pine needles that following weekend.
Todays snapshot of the CFS “Climate Forecast System” has normal start to wet season with no early winter.
Wednesday 5:30 PM
Upper low continues to rotate over SE NV. “SPC”, shows good divergence over Western Nevada, and an 850-250mb couplet along the Ca/NV border near Bishop Ca later this afternoon. PWATs are as high as 1.3 over SE Inyo while the moisture gradient thins pretty quickly to .7 over Mammoth Lakes. Radar has echos over Northern Clark County into Nye County and across the border into SE Inyo County. A few hours ago, there were heavy rains between Desert Rock Nv and Vegas.
Over all it is interesting to note that spokes of divergence at 300mb were rotating around the center of the low…many coupled with areas of lower level convergence. Lifteds were -1 to -3 between western Nevada and southern Inyo county.
Upper low over Nevada now with counter-clockwise flow at 700mb back washing some moisture into the Eastern Sierra over the next few days. Yesterday there looked to be a storm over the Yosemite valley. For those that want an update on the Rim fire, here is a link to a good blog that will help: http://northcasmoke.blogspot.com/
High temps the next few days may be a bit cooler, just because of the added moisture and cloud cover with highs closer to 70 in Mammoth Lakes. Lows in the 40s.
The outlook finally shows the upper low moving east by Friday night so that the weekend is clear and dry of moisture. High temps will rise again into the weekend back into the mid 70s with lows in the 40s.
There appears to be major changes to the larger scale features over both the eastern pacific and far west that will put an end to…the persistent hose of monsoon moisture moving out of Mexico and effecting the desert southwest about the middle of next week. The first series of Fall like Trof’s that have been advertised for over a week now by both the Climate Forecast System and GFX would begin to move into the great basin about Tuesday or Wednesday. This may be a bit fast but it is significant change and about time. The Climo is favorable for a series of Trof’s to begin their march in the Pacific NW about the 3rd to 4th week of September. The GFS advertises for the Central Sierra, thickness cooling, gradient, stronger winds and cloudiness, all from the Gulf of Alaska…… and snows for the Cascades!
Dr Howard and the Dweebs………………………………………………………….:-)