The best way to obtain actual up to the minute weather information at our flying field is to call the phone number 916-366-3371 and listen carefully to the recorded message. This is the phone number to AWOS-3 at Mather Airport - the automated weather service design for full scale pilots. When you call, the machine plays the recorded information in the loop – if the machine picks up the phone in the middle of the loop, just wait till the message finishes and in few seconds it will start playing the recording again. The message usually is updated as often as every one minute.
Automated weather reads the following information (in that order):
- reporting point (airport name),
- observation time in Zulu time zone,
- wind direction (from which the wind is blowing) and optional variable wind direction (in degrees of the compass),
- wind speed and optional wind gusts (in knots),
- visibility and optional variable visibility (in miles),
- sky condition (in oktas), and optional cloud ceiling height (in feet),
- optional liquid precipitation accumulation (in inches),
- temperature (in degrees Celsius),
- dew point (in degrees Celsius),
- altimeter setting and optional density altitude.
A the end of the automated recording there might be a "remarks" message related to any information about the airport condition and surrounding activities.
Here is the example recorded April 14, 2013 at 11:24 am local time (click on Play button to play the recorded message):
"Sacramento Mather Airport automated weather observation one-eight-two-four Zulu weather: wind two-niner-zero at four; visibility missing; sky condition clear below one-two thousand; temperature one-seven Celsius; dew point one Celsius; altimeter: two-niner-eight-niner."
This particular report contains all mandatory elements but does not have any optional weather elements - the weather was very nice for flying that day.
So how to read it? It is much simpler than it sounds. The following weather elements can be extracted from this short message:
- Reporting point: "Sacramento Mather Airport" – no explanation needed here
- Observation time: "automated weather observation one-eight-two-four Zulu weather" – that is 18:24 Zulu time. Looking at two clocks on the home page you will find, that it is 11:24 am local time (at summer time we are 7 hours behind Zulu time, in winter time we are 8 hours behind Zulu time ).
- Wind direction: "wind two-niner-zero" – that is from compass direction 290 (word “niner” is used for digit 9). MASM runway is aligned at 6 degrees (compass direction) therefore the wind from 290 is blowing directly from the west - almost perpendicular to the runway (76 degrees to the runway center line).
- Wind speed: "at four" - the wind speed is reported in knots, which is about 1.15 times more than in miles per hour, so the reported wind speed 4 knots is about 4.6 mph.
- Visibility: "visibility missing" – at this time the sensor reporting visibility was not working, so it is "missing". Normally it will report the number in nautical miles or “more than 10” which is like “unlimited”.
- Sky condition: "sky condition clear below one-two thousand" – sky is clear, and there are no clouds below 12 thousand feet.
- Liquid precipitation accumulation – was not reported, as the weather is dry (no rain).
- Temperature: "temperature one-seven Celsius" – 17 degrees in Celsius is about 62 F.
- Dew point: "dew point one Celsius" – 1 degree in Celsius. If dew point is close to the current temperature, it means humidity is high and there is a chance of fog developing.
- Altimeter setting "altimeter: two-niner-eight-niner" – 29.89 inches of Hg