During our recent storm, 93 of Iowa's 99 counties were simultaneously under a Blizzard Warning. Is it possible to assess how much of that area experienced blizzard conditions and thus verifying the warning? A blizzard is defined as at least a three hour period of visibility reduced to 1/4 mile due to falling or blowing snow with wind gusts above 35 MPH. A primary means of meeting those requirements is provided by the automated airport weather stations and one such example is shown by the featured chart for Mason City. The plot combines the period the Blizzard Warning with automated observations of visibility and wind speed. The times of reduced visibility is assumed to be due to snow in the air. The darker shaded (bluish tint) region around 6 PM on 15 March 2026 represents a period meeting blizzard criterion. There are a few other less subtle regions that represent blizzard criterion conditions not meeting the three hour requirement. As is typically the case, a blizzard warning encompasses a time period with blizzard-like conditions, but only a limited sub-region of time will verify the warning. You can run this chart for other airport locations in the state and you will find a similar story. Of course, there are caveats galore with this type of verification as airports are often in more urban areas, which tend to experience less visibility reductions than in the rural without much of obstructions.

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Tags:   blizzard