====== Adverse Weather ======

==== Observing ====


Stay aware of the weather conditions while observing.
Look outside occasionally. There are many [[cso:weather:weather|weather resources]] available, including the [[http://www.eao.hawaii.edu/weather|EAO weather summary]].

In case of adverse weather, close the shutter immediately. Remember it takes quite a long time (15 min) to close the shutter completely.  

When observers are present at the telescope, any of the following conditions preclude observing. Close the shutter if any occur:
  * //Relative humidity// outside the dome above 80%. 
  * //Wind speed// at the JCMT sustained above 35 mph (16 m/s). 
  * //Rain//, //snow//, //sleet//, //ice//, //fog//, or other precipitation. 

[[cso:policy:remote_obs|Remote observations]] require  better conditions. Do not observe if any of these occur:
  * //Relative humidity// outside the dome above 60%.
  * //Wind speed// at the JCMT sustained above 30 mph (13 m/s). 
  * //Rain//, //snow//, //sleet//, //ice//, //fog//, or other precipitation. 

=== Caveats ===

  * The CSO hygrometer and thermometer are mounted inside the dome. So if the shutter is closed, the temperature is usually higher and the relative humidity lower than outside. 
  * The CSO does not have a working anemometer. As a proxy, watch the JCMT wind speed. If the JCMT anemometer is off line, watch the SMA wind speed. 


==== Evacuation ====

  * //Do not become stranded// by adverse weather. Anticipate the need for a quick evacuation if weather conditions deteriorate.

  * //Ice//
    * Icy conditions can occur anytime of the year. 
    * Icy conditions can occur quickly and without warning.
    * If the temperature below freezing (0 °C) and the humidity is high, ice can accumulate easily everywhere including on vehicles and on the road.
    * Beware of falling ice! If ice has formed on buildings do not park near them and use caution when entering the dome. Shutter movement may cause ice to fall!

  * //Wind// 
    * If wind speeds exceed 60 mph (27 m/s), evacuate.
    * Park vehicles pointed into the prevailing wind. Take care opening vehicle doors.

  * //Snow//  
    * If it starts snowing, evacuate. 
    * If snow is expected, stow the dome 90 degrees to the prevailing wind direction before leaving.
 
  * Always put vehicles in the lowest gear possible when descending. This is especially important if conditions are icy.
  * Be prepared to mount chains on your vehicle.
  * Comply with MKSS recommendations regarding observatory access and chain usage. 
    * Watch the HP white board near the main entrance for current road conditions. 
    * If MKSS issues an absolute evacuation order or closes the road, all facilities must comply.
  * Emergency phone numbers are posted near the control room phone and on the [[cso:logistics:contacts]] page as well as in the notebooks in the vehicle glove boxes. Cell phone reception is sporadic above HP.