[Chaos-l] [Medoc-mountain-men] Weather forecasting-- great article in S&T

[Allen Davis]

Thanks Mark for providing this info.  allen

E. Allen Davis
starstorm151 at embarqmail.com

"M'Illumino              "I am enlightened
D'Immenso"              by the immensity."
                                   
  -Ungaretti               -Ungaretti

On Mar 2, 2010, at 10:09 AM, Mark South wrote:

> Hi,
> Sky and Telescope Feb 2010 issue has a great article on Astronomy Weather forecasting that goes beyond the Clear sky clock.
> 
> The supplement to the issue online with some great links is here:
> http://www.skyandtelescope.com/howto/visualobserving/79770137.html
> 
> The big idea in this article is that we should cross check with multiple weather models, starting with a general forcast and CSC, then moving to more complex  models for more fine tuning such as the Global Forecast System (GFS) .  GFS is a great modeling system and predictor for the week (in addition to  CSC and Accu-weather) for info on clouds, rain, etc.  and is updated four times a day unlike CSC which is updated only twice a day.   The author says regarding the CSC, "...that's good but not ideal; a lot can change in 12 hours."
> 
> Click here for GFS and NAM (North American Mesoscale)
> http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/
> 
> Quoting the article:
> "The GFS map...shows predicted precipitation and mean sea level pressure (MSLP).  Rainy areas are best avoided while high-pressure systems are most likely to have cloudless skies.  But if the isobars (lines of equal pressure) are squeezed tight together, expect high winds and poor seeing.
>     Diffrent layers in the atmosphere are labeled by pressure at that altitude.  The map showing relative humidity @ 700 millibars (about 10,000 feet) is labeled "700 mb RH."  Cloud cover is likely if this value is above 70%.  High humitity at 300 mb (30,000 feet) is likely to cause cirrus clouds.  If you see high winds at 300mb, it meas that the jet stream is overhead, which usually causes poor seeing."
> 
> Great stuff.  I'm going to start looking at these sites in the future to make better decisions.   For example, it looks like Friday is going to be a quite clear according to NWS and the GFS.  GFS says at 84 hours out from today that 700 mb RH is "0" and 300mb is "0" so  it apears that it will be quite clear and some good seeing.   I'm just learning this.... does anyone agree with my findings or disagree for Friday's weather?  :)
> 
> Kind regards,
> Mark South_______________________________________________
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