Wednesday, August 19, 2015

"Heat Wave" Designation A Bit Arbitrary, But What Are You Going To Do?

A hot, hazy view of Vermont's Lake Champlain and Mount Mansfield.
An arbitrarily designated heat wave his underway
in the Green Mountain State now.  
With a forecast high of 90 degrees today, the nearest major weather station to my house, Burlington, Vermont, will have had three days in a row that reached 90 degrees.

That makes for an official heat wave when you get three days in a row at or above 90.

Like most official designations in weather, the definition of a heat wave is kind of arbitrary.

I mean, what looks more like a heat wave to you - three days in a row that barely make it to 90? Or this theoretical sequence of high temperatures for a week: 97, 96, 89, 94, 100, 89, 98.

That week long streak of weather that I invented is not an official heat wave. There's not three consecutive 90s. But to my mind, that sure is a heat wave, and worse than just three days of barely 90 degree weather.

But that's the problem with weather, and keeping weather records. There are so many variables involved. You have to settle on one.

It's probably true with any kind of weather catagorization. A tropical storm does not become a hurricane until its sustained wind reach 74 mph or more. But a 75 mph hurricane zipping through a lightly populated area will cause much less havoc than a 60 mph tropical storm stalling over a big city and dumping torrents of heavy rain.

Likewise, an EF1 tornado has winds of 86 to 110 mph, while an EF5 packs winds of over 200 mph.
But an EF5 passing over open farm country will cause much less havoc than, say, an EF1 sweeping through downtown St. Louis.

But, we humans have a need to compare and contrast everything. At least as importantly, it's good to have a systematic way of catagorizing weather. Is a certain phenomenon becoming less or more frequent? If so, where is this happening most.

That forms the basis for virtually every study as to how and why the weather and the climate is changing

Which means I won't nitpick over tiny little heatwaves like the one underway now in Vermont.

You have to catagorize everything consistently, but

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