|BACKYARD METEOROLOGY: WIND SHEAR
METEOROLOGIST JEFF HABY
When observing the wind, two observations that can be made in the backyard are a relative wind speed and the influence of the wind on
clouds. Wind shear is a component that can make thunderstorms severe or more severe. Wind shear can increase the longevity of a thunderstorm,
contribute to damaging wind gusts, larger hail, heavier rain, vivid lightning and can help with the generation of a tornado.
Wind is reported by a wind direction (direction wind is coming from), a wind speed and wind gusts when applicable. With experience, an
intuitive sense can be gained for how strong the winds are and how strong the wind gusts are. Compare the reported wind speed and gust
speeds at a nearby observing station or with a local instrument with the wind that is experienced at home. With practice over many days,
a good sense of wind speed and gust speed can be developed. Surface wind is important for thunderstorms because the inflow into a storm
increases as surface wind increases. A stronger inflow can lead to stronger storms and a higher tornado potential.
The movement of clouds will aid in the observation of how the wind changes with height. Ideally, low level, middle level and high clouds
will be present. Note how relatively fast the clouds are moving and the direction they are moving. If the clouds are moving at significantly
different directions with height then that is a sign of strong directional wind shear. For example, if low clouds are moving from the
south and middle/high clouds are moving from the northwest then that is an indication of strong directional shear.
Upper level speed shear can be noted by how the wind interacts with towering cumulus clouds. Strong upper level winds will quickly
produce a large anvil when convective clouds penetrate into the upper troposphere. Strong speed shear will help tilt a thunderstorm
and this helps increase the longevity and severity of a storm.