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

[Mark South]

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 
-------------- next part --------------
HTML attachment scrubbed and removed