Question submitted by Cody Simmons
Cody, wind measurements are taken with anemometers located 10 meters above ground level (about 33 feet), at official Environment Canada weather observing sites. The latest anemometers are changing from a rotating cup variety of the past, to a new sonic version, with no moving parts, in a replacement program that began about a year and a half ago.
The "wind speed" reported in each observation is an average speed for the most recent two-minute period prior to the observation time. This is also considered the "sustained wind" for routine surface observations (just to confuse matters a bit, in hurricane forecasts, the sustained wind is a one-minute average). This two minute average is calculated from a series of 24 five-second average values.
A wind "gust" is also reported when the peak "instantaneous" wind during the most recent ten-minutes prior to the observation is more than 10 knots greater than the lowest "lull" in the wind during that time. If that is the case, the highest instantaneous wind during that ten minute window is reported as the gust value. The wind speed is recorded by a pen mark on piece of paper held on a rotating drum, attached to the anemometer output. Hence the gusts is the spike in the chart that rolls out with tme.
A squall is a sudden increase in wind speed which is typically associated with active weather, such as rain showers, thunderstorms, or heavy snow, but which lasts much longer than a gust. Squalls refer to an increase in the non-sustained winds over an extended time interval, as there may be lower gusts during a squall event.