This was a practice session, posted in real time as it evolved, on to Williams Today beginning on Wednesday night – starting with a look at the upper level charts to see if conditions favor a flight on Saturday – three days from now. – See the link to the Forum entry here.
I start my evaluation by going to the VSA web page for “Weather – 2018″/ select UNISYS/ select channel 300 mb/ select GFS 3.5 day for 00Z SUN 21 OCT 18 (that’s 5 pm Saturday).
See this chart…
see the jet stream from Alaska to Chicago, see cut off low overhead California
now change to the 500 mb, see Low in same place, see AVort is green over the Mendos. That’s good….
now go to the 700 mb
Low a bit to the south west of us, but still overhead. VVel is green over mendos – that’s good. iso bars (really NOT iso bars, but heights of the pressure level, but they serve the same purpose, so i cal them iso bars in stead of height bars) … as i was saying, iso-bars far apart – thus light winds at 10,000 ft.
now look at the 850 mb
The temps over the mendos is 3rd degree orange = 16 to 18 c that’s warm . that’s NOT good. may be stable air. isobars spread tells us it is light winds at 5,000 ft. It is no wonder the air mass overhead our area is warm, since it is moving over the land mass from the south. It is NOT our usual cold pacific air.
Now the last UNISYS chart to see is Relative Humidity / Showalter Index abbreviated RH/Show
very dry, 4.9 SW is low over Redding – not bad, maybe an SW of 5 to 7 over the mendos, but no cu!
Lots of sunshine, and not expecting high cirrus. Light winds, expecting thermals over the mendos.
Googled “sunset on 10/20/2018” … it says 6:23 PM.
Googled “winter 2018” … it says winter starts on Thursday 12/21, ends 3/20/19.
Point is – sun angle is low in late fall (therefore not a lot if surface heating) , so not much heat 2 or 3 hours before sunset.
Plan to be on ground by about 4 PM.
generally it looks very promising… except for the stability of the air.
NOW, continue over to the next page of this saga….
… go to the next day here… https://www.valleysoaring.net/seminars/sem-2/wx-fcst-2/