90 Days After a Fog… (Part II)


(Click here to go to this blog’s home page.)

Central Iowa fog on March 8th, 2010. (Click photo to enlarge.)

Although the fog yesterday morning at Perry, Iowa, wasn’t nearly as dense as the fog in northwest Iowa on January 18th and 19th, yesterday’s fog did prevent me from traveling.  It also made me think back to my January 20th post. In that post I referred to the theory suggesting that 90 days after a fog there will be precipitation.

I emailed Elwynn Taylor, Professor of Ag Meteorology at Iowa State University, to ask for his explanation of the 90-days-after-fog-precipitation theory. He was kind enough to respond and to give me permission to quote him.

My question to Elwynn: “Is there a correlation between fog and 90-days-later precipitation, and if so, what is the explanation of the correlation? (Many people I’ve talked with say the 90 day theory is bogus/chance since it precipitates frequently anyway. I’d like to respond intelligently to them.)”

Elwynn’s response: “In the summer the 90-day to fog (in some locations it is the 100 day-to fog) concept is not valid.  As you say, there could be rain about then anyway and statistically that is about how it turns out.

“In the winter a wide-spread Midwest fog is simply the viewing of the ‘breath of the Gulf of Mexico’ and it is much like seeing your own breath on a cold day. Now if the Gulf air is entering Iowa in January (not a common thing) it may very well indicate that the Gulf air flow will be strong and/or early come spring. (Gulf air begins to dominate much of the Midwest after mid-March each year.) If it is early and strong…. yes, this results in a wet spring some 90-days after the fog was first a major thing.”

Well, the dense fog did enter Iowa in January. So it was early…and strong. It will be interesting to see what our spring will be like “some 90-days after the fog was first a major thing,” which I’m thinking was January 18th and 19th.

(Click here to go to Louise Shimon’s blog’s home page.)


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One Response to “90 Days After a Fog… (Part II)”

  1. katie Says:

    Innnteresting. I had Elwynn Taylor as a professor at Iowa State.

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