Automated Weather Stations Are the Sensors Behind Fire Weather Numbers
Fire weather arrives as numbers, and almost all of those numbers come from a remote automated weather station: a solar-powered mast reporting on the hour, unattended, from a ridge or a valley floor. A standard station carries an anemometer and vane at 6.1 metres above ground, a shielded temperature and relative humidity probe, a tipping-bucket rain gauge, solar radiation, and, distinctively for fire work, a fuel temperature probe and a fuel-moisture stick, a standardised wooden dowel weighed electrically as a proxy for 10-hour dead fuel moisture. Knowing the hardware changes how you read the data. Wind is a short average at one height on one site, so a valley station does not describe the ridge above it; the humidity probe has a response time and a known dry bias when wet; the fuel stick is a stand-in, not a measurement of the actual fuels around it; and a station reports hourly, so a wind shift between observations is invisible. Siting standards exist precisely because a station in a hollow or under a tree reports a different climate. After this Concept you can read a station observation as an instrument reading with a location and a lag rather than as the weather.
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Fire weather arrives as numbers, and almost all of those numbers come from a remote automated weather station: a solar-powered mast reporting on the hour, unattended, from a ridge or a valley floor. A standard station carries an anemometer and vane at 6.1 metres above ground, a shielded temperature and relative humidity probe, a tipping-bucket rain gauge, solar radiation, and, distinctively for fire work, a fuel temperature probe and a fuel-moisture stick, a standardised wooden dowel weighed electrically as a proxy for 10-hour dead fuel moisture. Knowing the hardware changes how you read the data. Wind is a short average at one height on one site, so a valley station does not describe the ridge above it; the humidity probe has a response time and a known dry bias when wet; the fuel stick is a stand-in, not a measurement of the actual fuels around it; and a station reports hourly, so a wind shift between observations is invisible. Siting standards exist precisely because a station in a hollow or under a tree reports a different climate. After this Concept you can read a station observation as an instrument reading with a location and a lag rather than as the weather.
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