Why don’t you know exactly when it’s going to rain?

Rain shaft over Huntsville by Naomie Nelson (6/25/16)

It’s a valid question that deserves a real answer: why can’t we tell you precisely when it’s going to rain?

A man once told me that meteorologists are victims of their own success; we’re more accurate than many critics are willing to admit, so those missed forecasts or inclusions of ‘uncertainty’ instead of a straight ‘yes’ or ‘no’ answer stick out like a sore thumb.

Actual e-mail

In this day of what I like to call the me-centered universe, apps like Live Alert 19 give you very specific data on an hourly basis. Data is good; data helps us plan, but data does not always give you the perspective you need to make a good decision about the weather.

An example of the uneven, scattered coverage of rain and storms from August 9th

That’s where the forecast starts to sound like the Waffle House menu: scattered, smothered, and covered.

Understanding where numbers come from, or where phrases like ‘thunderstorm chaos’ or just the general ‘scattered’ and ‘hit-or-miss’ requires some thought.

How do thunderstorms form anyway?

There are countless books and articles that theorize thunderstorm development. We know the environment that promotes them, but because they come to life and dissipate on a scale that is smaller than the weather observation network. That means specific information about pop-up showers and thunderstorms has to be more of a now-cast than a forecast.  It’s like trying to track and forecast bubbles in a boiling pot of water.

Throw in the fact that we’re talking to thousands of people in a rectangle that goes from the Mississippi border to the Georgia border and from Cullman north to Fayetteville, and that ‘forecast’ for a timeline on a day like this becomes more of an advisory to be ready for the chaos of hit or miss downpours.

Here’s how the rain turned out today, by the way.  Some got a lot, some got a little, and just as many got zero.

Need more info about the weekend or next week? They’re always online at WHNT.com/Weather and in the “Daily Forecast” section on Live Alert 19!

-Jason
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