Archive for July, 2014

Quick Update: Sunday AM  Wind shift has pushed smoke back to west side….

This will continue for the next 36 hours…

Rains will begin either later this Am with more certainty this afternoon..  I do hope that Buddy Guy gets done by that time….. but that is dubious at best..

Flash Flood Watch in effect from August 3, 02:00 PM PDT until August 4, 02:00 AM PDT

Deeper Moisture is working northward from a pool of about 2.00 PWAT Along the coastal section of Southern CA. It is interesting to note that the air mass over Southern CA is almost as saturated as Central Florida! And worth mentioning is that although all this moisture is around, not much in the way of rainfall is expected for coastal areas of Southern CA. That is because the atmosphere is not dynamically induced. Areas to the northwest north and east of LA it is a different story where convergence/divergent couplet is in place. IE  Right entry region od upper jet at work…

The upper low is expected to stall out over CA/NV the next several days so it looks quite wet with periods of rainfall.   Tonight….most of the night will be wet with rain.  Campers be aware of that….

The Dweeber……………………..:-)

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Today will be a slightly warmer day than Friday:

It will be partly cloudy with areas of smoke and even some denser smoke as the French fire in the San Joaquin drainage continues to burn out of control. It has now reached about 12,000 acres and is 15% contained. Some from this fire will affect the eastern sierra on and off now well into August depending upon wind direction. An Easterly Wave will move into the high country Sunday afternoon with Showers and thunderstorms. This system is likely to produce rain throughout the night.   Some thunderstorms could bring potentially heavy rain depending upon the amount of daytime heating we get early in the day. This is an organized area of moisture and precipitation that is moving up from Baja today. Upper level moisture has already reached the deserts of Southern California. The trajectory is right up through Eastern Ca Sunday/Night. The silver lining is that it will most likely disperse the smoke for a while…..  The Owens Valley is under a flash flood watch beginning 5:00am Sunday morning.  Campers, hikers and outdoor enthusiasts should stay in touch with advisories that will be forth coming later today and tomorrow…..There is the possibility that the Flash flood watch for the Owens Valley may be extended north to include Mono County for Sunday as well.

I will have an update on this developing weather system Sunday AM………

Dr Howard and the Dweebs………………………………..:-)

Friday AM Update:

Light North East Flow has suppressed smoke back to the west side of the sierra for the moment. This will change as the prevailing winds are from the SW…..and as the daytime heating occurs, the smoke from the west side will roar back into the Mammoth area this afternoon. It will be smoky this evening as well with a slight chance of Thunderstorms this afternoon and evening. Smoke from the fire on the west side will continue to move back and forth periodically.

There is an area of disturbed weather (Easterly Wave) over the Sea of Cortez that will move up into Southern CA later today and make its way into Southern Mono County later in the day Sunday.  If it does, we’ll not have to deal with smoke. However we may have to deal with rain and thunderstorms beginning later in the afternoon Sunday and evening. This is the type of weather pattern that does not clear up after sun set and so rain is a good possibility Sunday night as well. The system  in the models has been trending further north in the most current guidance. This would bring heavy rain producing thunderstorms to at least the Owens Valley and Southern Sierra with Flash Flood potential in some areas. It will more then likely bring rain to the Mammoth area as well….

The Dweebs will keep an eye on this system and model trends…

Now a special edition from Toms Corner….

Models showing enough instability today ie(CAPE,LI) along with low level convergence and weak upper div along Sierra crest for another day of afternoon TSTMS. Many of these storms may drift or reform further E with late afternoon zephyr. Saturday looks to be dynamically suppressed and to stable for TSTMs especially northern Sierra where NVA and pos LI forecast. Could see isolated activity srn Sierra and Whites with lingering instability and better forcing. Things get very interesting by Sunday as several weak vort features or easterly waves along the srn periphery of 4 corners high consolidate with another vort center west of NRN Baja to spin up a larger vort max which tracks nwd into Srn Sierra and srn Nv. Its interesting to watch the rr (right rear ) entrance region of the 200 mb jet and its associated 250 MB Divergence as it expands nwd and intensifies on Sunday.  The 200 mb jet max goes from around 50-60 kts over srn Utah today to over 80-90kts in srn Idaho Sunday. I believe

this is a result of convective feedback spinning up stronger vorticity and jet speeds as the models indicate. You can see the H5 vorticity centers and 200 mb jet to north become stronger as more convection developes over Srn AZ and SRN CA. The question again will be if the extensive cloud cover on Sunday will allow widespread deep convection to develop or will it just be overcast with rain and a few embedded Tstms. Or will there be enough dynamics (DIV/CONV coupleting) to produce enough UVV to overcome the lack of solar heating. High PW airmass with sufficient CAPE and relatively slow storm notions from south for locally heavy rainfall and high flash flood potential if/when anything gets organized Sunday and possibly into Monday.  Stay tuned

Tom
Retired Leed forecaster
NWSRNO

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Light WSW flow in the lower levels has pushed smoke from the west side of the sierra over the pass and into Mammoth.  It appears that it will be a pretty smoky night up until about 11:00AM Friday morning. By the afternoon some improvement is expected until the evening hours. We will have variables amounts of smoke now until the return of the southerly flow. That appears to happen later Sunday as the upper flow backs to the south again into early next week….

An update in the morning……..

Come-on   Monsoon!……

Tuesday:

Deep moisture remains over the eastern sierra. Areas with good sun in the morning will benefit from the convection process (IE Surface heating)

While there is no significant trigger today…scattered thunder will be heard in many areas, with plenty of rain showers.

The latest guidance does show several Vort centers bubble up from the south. Thus Wednesday should be a more activate day and evening with more of a potential of localized heavy rain….

We go back to isolated coverage Thursday…..with warmer temps as well.   Another surge of Moisture returns Sunday from the South….

Monday Afternoon:

Expect Scattered Thunderstorms each afternoon and evening through Wednesday…with local areas of heavy rain…….

Saturday AM Update:

High level moisture is streaming Northwestward from an MCC over the Central Sea of Cortez, MX.  SST’s there are nearly 90F degree’s.  Blow off from those storms has moved into the Southern CA Deserts with the leading edge now showing up over the Owens Valley. The Upper flow is now backing from the South over Mammoth Lakes and will veer more SE the next 24 hours. High and mid level moisture will be making a return over Mono Co over the 24 hours with much deeper moisture by Monday AM.

New 12z GFS had dew point temps in the low teens over Mono County this Morning. The model progg’s a steady increase in the Dew Point temperature the next 60 hours…so that by Monday morning the Dew Point is expected to be near 40 degrees over Mammoth. If Monday morning is mostly sunny, the odds for rain in the PM will be greater then 40% in Mammoth as the best forcing and vertical motion is that day.  There will be plenty moisture around Tuesday and Wednesday. However, the dynamics are not as favorable. So Thunderstorms Tuesday, yes….but more isolated and convergence driven.

The Owens Valley is expected to have Dew Points into the low 50s by Monday evening and so it will be a pretty muggy Monday night by the valley’s standards, with nighttime lows in the upper 60s or even 70 degrees. Daytime highs will cool to the mid to upper 90s the first few days of the new week.

Tuesday through next Friday now offer a continuing threat of thunderstorms for Eastern CA……

More on the changes Monday AM……

Dr Howard and the Dweebs…………………….:-)

Friday Update:

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