ATIS
ATIS is valid for 5nm around the Airport Reference Point. Therefore AGL. Wind direction is in magnetic to correlate to runway directions / RWY in use (ATIS includes which RWY is in use) = if the RWY in use is mentioned, directions are in magnetic (spoken word by ATIS, ATC, Met report for a specific airport)
Automated systems uses multiple readings now = lowest laser reading measured during the last hour (30 min at international airports). Multiple readings eliminates the possibility of incorrect readings when laser beam just so happen to miss the cloud when it takes a (only one) reading e.g. BKN cloud cover. So, it gives a better overall report. Read the footnote in the MET section of the AIP.
ARFOR are above MSL because it covers areas outside the 5nm radius of the airports and the pilot must add ground elevation to ensure safety heights, flying altitudes or Flight Levels. Wind directions are in True = no RWY mentioned, thus enroute winds converted to magnetic using local variation.
Last edited by Nirak; 29th Jun 2012 at 07:01.