Outstanding Soaring: California Mojave, Owens Valley, Western NV -Fri-Sun 08/26-28

On Aug 28, 2:23*pm, Alex wrote:
On Aug 27, 6:19*pm, Mike the Strike wrote:









On Aug 26, 4:58*pm, Alex wrote:

On Aug 26, 3:04*pm, Ramy wrote:

On Aug 26, 8:35*am, WaltWX wrote:

Ramy,

I agree with your assessment. My focus for the good weather is aimed
at the Owens Valley, and Mojave Deserts (south of Bridgeport). *More
moisture spreading over entire area on Saturday with cloud bases
15,000-16,000 north of Bishop instead of 17,000msl. Widely scattered
TS in the usual hot spots but the cells should be fairly small and
short lived. *Sunday, as Alex pointed out below, looks a little drier
everywhere... still at least a very good to outstanding day.

Walt, Wx

On Aug 25, 11:51*pm, Ramy wrote:

On Aug 25, 5:45*pm, WaltWX wrote:

Take a look Dr Jack...

Outstanding soaring weather Fri through Sun. *Lift rates 700-800fpm
average... much stronger in those 10 per cent...

It's a toss up between Fri and Sunday. *The Mojave Desert, Owens
Valley and Western NV show full cu coverage bases 15,500 to 17,500. It
appears to be dry enough that only isolated thunderstorms will form in
the normal "hot spots". *Early trigger times also.

I reviewed Dr Jack this afternoon with a long ago crew of mine, John
Halcrow. *For Crystalaire, the pattern on Friday looks as good as I'v ever seen it. *BL (thermal) max heights 17,500msl (of course cloud
bases will limit altitudes to a little lower).

I'm coming back out Saturday to give my 750 km triangle another try
from Inyokern (please... leave me room for an 11:30am takeoff

Walt Rogers, WX

I don't see the same outstanding conditions when reviewing the NAM
blipmap, especially for going north towards Minden. Bases only 15-16K,
lots of moisture with potential for overcast and OD and stronger wind
to the north. Could still be good but probably not as good as it was
the last few days.

Ramy- Hide quoted text -

- Show quoted text -

One little known secret of Dr Jack Blipmap is the "Total Cloud Cover"
parameter. This is one of the most reliable parameters I've seen to
detect overcast. If there are white areas you are pretty much
guarantee that there will be at least some level of overcast. It does
not tell if it will be high cirrus or mid level overcast, and how
thick it will be, nor if it will be persistent or short lived. But it
hardly ever fails to detect that there will be some degree of overcast
in the area. It indicated *successfully today pockets of overcast
especially in the southern zones of region 11 and 12, and more so
tomorrow over the central Sierra. None for Sunday.

For those who prefer looking at the RASP, besides the Avenal one,
there is one which covers the whole Sierra:http://www.norcalsoaring..org/BLIP/SIERRA/index.html
It has 'BL Cloud Cover' but I did not use it enough to confirm if it
provides the same as the NAM Total Cloud Cover.

Ramy

Also on the Dr. Jack RASP sites, if the operator has set up locations
for plotting forecast
soundings as *Skew-T diagrams, *you can see on the left side of these
diagrams
black lines corresponding to forecast cloud layers. *These *try to
forecast both the heights and thicknesses *of cloud layers. * *These
include *cloud layers that
are above the "boundary layer" that most of the blipmap diagrams
concern themselves with, *such as high cirrus layers. * *If there is
also a similar layer marked in green over on the left side
representing *"cloud water in g/k", that seems to correspond with the
chance of
precipitation. * An example of this could be seen today on some of the
soundings from the Avenal RASP, such as this one:

http://alcald.homelinux.org//RASP/AV...8.curr.1400lst....

Alex Caldwell

Rapid Refresh plots have this and more and are a lot more accurate
than RUC or NAM based Blipmaps. *It'll be nice when RR goes online and
replaces RUC.

Mike- Hide quoted text -

- Show quoted text -

The RASP blipmapshttp://www.drjack.info/RASP/index.html
are quite different than the RUC and NAM based blipmaps.
I'm not an expert on this stuff, so take this with a grain of salt,
but I have been running the RASP on my own for a
few years now for our club. There appear to be some misconceptions as
to the differences between Dr. Jack's *RASP blipmaps and the orginal
Dr. Jack RUC and NAM blipmaps, as well as the relationship of the RASP
to the new Rapid Refresh.
I apologize in advance to Dr. Jack, *if anything I'm saying below is
bogus.

The RASP blipmaps (as opposed to the original Dr. Jack RUC and NAM
blipmaps), use use a "WRF"
computer model (version 2) *which is *the same model the Rapid Refresh
is using, except Rapid Refresh is using a newer
version, WRF version 3.2+ . *Some people running the RASPs are
switching over to the WRF version 3 also.
The RASPs in the US are generally "initialized" using ETA (NAM) "grib
files". In Europe the GFS model is generally used for
initialization. * But
from there on, *the atmospheric physics calculations
are done based on the WRF model, not NAM or RUC. Dr. Jack has also
used the RUC *instead of ETA or NAM to initialize the *WRF
model in some experiments he has done. *Basically, what Dr. Jack did
with the RASP is to take the WRF model, and
have it output the various blipmap "parameters" he developed that are
of particular interest to soaring pilots, *plotting them using suite
of *plotting programs
called "NCL". * The advantage of the RASP over the original RUC and
NAM blipmaps is whatever improvement the WRF model offers, plus the
much
higher resolution - generally 4km for starters,
and on up from there, as opposed to 20km with the original blipmaps.
This allows much more detailed computer modeling, *with the finer
overall grid resolution, and
much more detail with respect *to the
effects of local terrain, including terrain heights, terrain contours,
terrain compostition and soil types, seasonal variations in albedo
etc. *The big disadvantage of the
RASP is that it requires tremendous computing resources to plot this
level of detail over the whole U.S. or the globe, and
until recently, this would bring *even the *government's *computers to
their knees. *Hence,
you see volunteers running RASPs for small local areas of interest on
their own. *The new
Rapid Refresh appears to be able to overcome that limitation by being
able to run a 3km resolution WRF model for the whole US, also
including
things like radar data that were not available before.
The parameters the Rapid Refresh group are publishing are interesting,
and many are already useful to glider pilots, but they don't have the
same
type of soaring centric information available that Dr. Jack developed,
such as his "Cu Cloudbase where Cu potential is 0" and the many
others
we've come to know and enjoy from his work. *An obvious possible
future project might be to take the new Rapid Refresh system and get
the type
of output we've gotten from the blipmap soaring parameters. *I suspect
the RapidRefresh team won't do this for us on their own, unless maybe
they have a
fanatic soaring pilot on their programming staff!

Alex Caldwell
Central California Soaring Club
Avenal, CA, USA

Alex:

Thanks for your comprehensive explanation.

I have only recently had the opportunity to compare the operational
models with RASP model output for southern Arizona (Dave Leonard is
running it for us on his server). I had been using RR1 skew-T plots
for over a year now and have found them generally much more accurate
than any of the previous models. More recently, I have been looking
at all the RR output fields and find them very useful. The more rapid
cycle has enabled me to keep up with changes when the other models lag
behind.

My observations have been that the RASP output is very comparable to
RR (know I know why!) and nearly always better than any of the other
models. NAM has been generally best here, but RUC sometimes is
better, but neither is as good as the RASP output. It certainly is
very nice to have the soaring parameters.

The main problem I have with the RASP is the same as the original Dr.
Jack's output - the abysmal maps. I am looking forward to RR going
operational and getting someone to produce nice interactive maps from
the output. I wish I had more software skills, but it's way beyond
me!

Mike