Training Tip: What's up with the wind?
Weather conditions pilots focus on most in preflight planning vary by season as summer convection and high density altitudes give way to cold-weather concerns like slippery surfaces, frosted-over aircraft, or a temperature inversion that can change rain into treacherous airframe ice if it strikes an aircraft flying in below-freezing air below.
In any season it takes dedicated delving into details to assess flight conditions. Fortunately, one aspect of weather analysis that applies at any time of year is being able to check a surface analysis chart and get a big-picture idea about one of a light aircraft pilot’s main concerns: wind.
If this were a ground school class, a precocious student might raise a hand and challenge the notion that a METAR issued so early in the morning satisfies the example, because at that time of day, winds tend to be light before thermal activity fires up.
A fair point. So let’s look in on that same airport later. At 1853Z, the station reported, "35006KT 10SM FEW045 SCT095 BKN200 02/M01 A2971." An airport 50 miles southwest reported, “VRB06KT 10SM OVC100 03/M02 A2971.” Still light winds across the region.
What wind speeds and direction might you observe in the Midwest based on this surface analysis chart?
Check your “gustimate” against the 1854Z METAR at Iowa’s Des Moines International Airport: "30018G25KT 10SM BKN024 M06/M13 A3050."
Were you close?
A surface analysis doesn’t give a complete picture of weather. However, it should provide a general answer to the first question on many pilots’ minds before flying: “What’s the wind doing?”
Dan Namowitz
