The National Weather Service in Sioux Falls, SD issued a Wind Advisory Tuesday afternoon till Wednesday evening for a few counties in far northwestern Iowa. The featured chart looks into the time of day timing for when such events are in effect. The plot is effectively for Sioux County and shows the percentage of all 203 events on record for the site active during a given minute of the day. The diurnal signal is clear with the largest frequencies found during mid afternoon hours. This coincides with the strongest solar heating and mixing of the lower atmosphere, this mixing transfers higher momentum air to the surface, increasing wind speeds! The overnight frequencies are rather constant and are those events associated with strong surface pressure gradients between high and low pressure systems.

Voting:
Good = 10
Bad = 3