The weather_watch mailing list is a majordomo product to inform interested users about: 

       ________________________________________________________
      |                                                        |
      | "Forecasted Observing Conditions at ESO Observatories" |
      |________________________________________________________|


-To subscribe, send an e-mail to majordomo@eso.org which contains:
        subscribe weather_watch-list <myemail>

-Everytime a change of the forecasted situation is detected, an E-mail
is sent to you which contains the forecasted date/time of:

 ___________________________________________________________________
|           Sky Quality Conditions from best to worst               |
|                                                                   |
|  LowPWV--Nominal--HighPWV--VariableExtinction--Clouds---Overcast  |
| <.......photometric .....><..................><.non photometric.> |
|___________________________________________________________________|

   _______________________________________________________________
  |                    Message Protocol                           |
  |                                                               |
  | Clouds                5% to 80% Cloudy Sky in a 3-hourly mean |
  | HighPWV               Precipitable Water Vapour>10mm H2O      |
  | LongTau0              Wind Speed @ 200mb <20 m/s              |
  | LowPWV                Precipitable Water Vapour< 1mm H2O      |
  | LowPressure           Incoming Weather Front (+\-12 hours)    |
  | NegativeTemperature   Air Temperature <0 Celcius (+/- 1C)     |
  | Nominal               Nominal Observing Conditions            |
  | Overcast              >80% Cloudy Sky in a 3-hourly mean      |
  | ShortTau0             Wind Speed @ 200mb >50 m/s              |
  | StrongWind            Wind Speed @ Ground Level >15 m/s       |
  | Tair(C)               Forecasted Temperature at 30m above     |
  |                        ground (for enclosure thermal control) |
  | VariableExtinction    <5% Cloudy Sky and (>25% Transp. Cirrus |
  |                                     or Transparency Index<0.9)|
  |_______________________________________________________________|
                
-To unsubscribe, send an e-mail to majordomo@eso.org which contains:
       unsubscribe weather_watch-list <myemail>

                      -----------------------


Frequency of update of input data:

-5 time per day for cloudiness/pwv. Based on the 00, 03, 06, 09, 
and 12UT analyses, the forecasts are produced about 2 hours later.
-2 time per day for PTV (pressure, temperature and wind). 
Based on the 00UT and 12UT analyses, the respective forecasts are 
produced at about 06UT and 01UT (of the next day). 

A message is sent every day at 13h35 UT in all circumstances.
Following the 'no news=good news' principle, new messages are
sent in the intervals only when noticeable changes are forecasted. 

A sample of the message is available at:
http://www.eso.org/gen-fac/pubs/astclim/forecast/meteo/verification/weather_watch.update