Yoda: "Always In Motion the Weather Is"

Looking for a change in the weather? Wait a few minutes. Okay, maybe a few hours.

Today, we have two low pressure centers hovering over our region. One is in lower Michigan (dragging a trough behind it), the other is centered over southeast Ohio (dragging a cold front behind it).

Each of them spins counter-clockwise and each wraps moisture around itself. And as long as a low-pressure center is in the area, there will be a chance of showers in the forecast. Plus, as the trough pivots through our neck of the woods, it will create enough of a disturbance in the atmosphere that showers are likely.

Here's what the National Weather Service Forecast Office in Wilmington had to say about it in one of this morning's forecast discussions:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
856 AM EDT
SUN MAY 18 2008

.SYNOPSIS...
AN UPPER LEVEL LOW OVER THE GREAT LAKES WILL AFFECT THE REGION FOR THE REST OF TODAY...BRINGING A CHANCE OF AFTERNOON AND EARLY EVENING SHOWERS.

I'm leaving showers in the forecast for today. The NWS is calling for showers. Ben Gelber saw a chance for showers, too. The mets at the other TV stations say the same thing. We all agree on the same formula:

(2 x low pressure center) + trough = chance of showers

As the sunshine broke through the clouds this morning, the e-mails began rolling in. People had changed their outdoor plans for the day and were ticked off to see blue skies. As a rule of thumb, I'd never recommend changing your plans based on the weather... especially for a forecast that says "scattered showers."

The American Meteorological Society's Glossary of Meteorology defines the terms this way:

scattered—1. In radiation, see scattering. 2. A sky coverage of 1/8 through 4/8.
In U.S. weather observing procedures, this is reported with the contraction
“SCT.”

shower—Precipitation from a convective cloud. Showers are characterized by the suddenness with which they start and stop, by the rapid changes of intensity, and usually by rapid changes in the appearance of the sky.

When the forecast says "scattered showers," it means not every house in the viewing area is going to get wet. Some will. Some won't. Unfortunately, human technology and scientific understanding have not yet advanced to the point of knowing exactly when or where a shower will develop at any given time. However, we DO have the understanding and technology to know when Mother Nature may throw a few showers in a generalized area. That's where we are today. Scattered showers.

Don't change your plans. Just be ready for a shower or two... and an occasional downpour.