The Des Moines Airport automated weather station reported a thunderstorm yesterday afternoon along with southeasterly winds. The featured wind rose presents the wind speed and direction during which a thunderstorm is reported within the present weather observation of the site. Thunderstorms are driven by instability in the atmosphere, which is the combination of warm and moist air. Our primary source of that type of air is from the southeast, so it makes sense to see that wind direction dominate the frequency shown in the wind rose. While Iowa gets the warmest air from the southwesterly directions, that air is typically much drier and thus less likely to help promote thunderstorm development. More thunderstorms are expected today.

Voting:
Good = 18
Bad = 10
Abstain = 8

Tags:   asos   thunder