| Jacquielynn Floyd: No promises in weather forecasting 12/19/2000 By / The Dallas Morning News Caught in a cranky mood, Shakespeare complained in his 34th sonnet:
Why didst thou promise such a beauteous day
And make me travel forth without my cloak...?
He was writing about broken promises and disappointed love, but it could just as easily have been an angry valentine to some Elizabethan meteorologist. You might have sympathized with the Bard yourself Saturday, when we were promised a beauteous 70 degrees and were caught, cloakless and shivering, in the cold, raw wind.
How, you might have wondered, could they be so wrong? Don't they have computers? Haven't they got six kinds of radar? Can't they just look at the map and see that big purple thing coming?
The short answer is that there's a lot of data, but there are no guarantees. Weather forecasting has actually gotten much more accurate in the last 20 years, but it's still a prediction.
'It's statistics and probability'
"It's not a promise," said Kristine Kahanek, a meteorologist who works next door to us at WFAA-TV (Channel 8). "There are so many variables: It's physics and math, and it's statistics and probability."
She was much too polite to add: If you think it's so easy, bucko, just try it yourself.
After much concentration, I devised an analogy so oversimplified that I can grasp the concept.
Say you're supposed to be at Grandma's house in Waxahachie at 3 p.m. All you need to be on time is a clock, right?
But you need to know how long it will take you to get there. You need to know whether traffic will be heavy or light, and whether there's enough gas in the car, and whether you'll have to stop on the way to pick up your notoriously unpunctual cousin. You need to know where Grandma's house is, and how to drive, and how to tell time.
Even with all that knowledge, odds are you'll be a few minutes early or late. And random fortune could give you a flat tire, making you so late that supper's cold and everybody's mad at you.
"We never intend to get it wrong," Kristine said pointedly. "I'd say we're right 90 percent of the time."
After flipping through basic weather-data information, I'm astonished that anybody ever even comes close. This is one of those disciplines that really do take a rocket scientist to figure out.
Dr. Fahrenheit, I presume?
I found the current NGM, ETA and AVN model outputs. I read about pressure units (one millibar equals 100 newtons, got that?) and discovered that the air is just loaded with gaseous ingredients and speeding molecules, that it's ripe with kinetic energy.
There's a type of precipitation called "graupel," as in, "Honey, I think it's graupeling out there, did you bring in the lawn mower?" There was actually a Mr. Doppler, and a Dr. Fahrenheit, and rain isn't shaped like teardrops – it looks like hamburger buns.
And that's the easy stuff. Computers collect reams of atmospheric data and produce those big maps covered with circles and arrows and wiggly lines, but it's the meteorologist's job to decide what the map means.
The one Kristine showed me Monday could have portended volcanic eruptions and hail the size of coconuts, for all I knew. It really is a job for professionals.
Unlike, say, LA or Honolulu, where the weather is often pleasant but boringly predictable, Dallas is a jumpin' weather town.
"We get the extremes," Kristine said happily, visibly perked up by the thought of sneaky fronts and sudden storms and mysterious upsets somewhere over Montana that could ruin the company picnic by Tuesday.
"We're here not for the nice days" – boring! – "but for the bad days," she said. "I'm not trying to tell you 'Fear for your life!' but you have to tell people about the potential for severe weather."
And remember, she said, that it's an educated guess, not a promise.
So if you travel forth without your cloak, you have nobody to blame but yourself.
Jacquielynn Floyd can be reached at 214-977-8065 and at
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