By Ben Ellison
Live Weather at Last
|New services bring benefits of powerful Nexrad weather tracking.|
The typical coastal boater monitors the weather by keeping his/her eye on the skies and occasionally putting his/her ear to the VHF marine forecasts broadcast by NOAA’s National Weather Service. It’s a useful but imperfect technique. For instance, how do you handle the classic summer lightning conundrum that came up in this column recently—a flat, hot summer day perfect for boating but with a chance of severe thunderstorms developing? Do you listen to that tedious synthesized voice on VHF all day? Wouldn’t it be great if you could see significant weather hundreds of miles away—even gauge its intensity and motion? Well, at this year’s Miami International Boat Show, no fewer than four brand-new products were announced that promise to make weather awareness while underway quicker, more visual, and more specific. They’re each different, but all share the common central feature of overlaying a chart with nearly real-time animated output from NOAA’s remarkable nationwide Nexrad weather radar system.
Nexrad, short for Next Generation Radar, became fully operational during the 1990’s, but many of us are only just now grasping its capabilities. Picture 158 radar domes carefully spaced around the country (including Hawaii and Puerto Rico). Each is 28 feet in diameter and contains a 750-kW scanner capable of seeing rain and snow—and birds, airplanes, and more—for a radius extending as far as 250 miles. Their output scans are high-resolution and color-coded to reveal gradations of intensity. All that output is piped to central super computers, where it is processed, even blended into large-area mosaics, and then offered freely to the public (and to independent weather organizations for use in forecasting and for commercial redistribution).
So what can Nexrad do for you? The Web screenshot on page 40 is some indication. It shows first how Nexrad covers almost the whole country to about 100 miles offshore and second how it paints a picture of active weather, or at least the precipitation that accompanies the most significant activity. (You can bet that’s a significant front moving through the central states.) Moreover, the picture was scanned just a few minutes before I opened the Web page and, unlike many satellite images, shows what’s happening underneath the cloud layers. Better yet (but hard to show on paper) you can “loop” the image—i.e., see a little movie of the radars’ scans over the last few hours—which truly helps you understand often complex system motions. You can make out areas of particularly intense precipitation by their “hotter” colors and thus identify fronts and—when more typically zoomed in to a few hundred miles around your location—even individual storm cells. In looping mode you can often tell if these cells are intensifying or breaking up and predict their track.
No doubt you’ve seen images like this narrated by a TV forecaster or on the Web (go to www.nws.noaa.gov and select “radar,” or find somewhat improved versions at independent weather sites like www.wunderground.com). And I’m sure that some well-equipped boaters use fast onboard Internet connections to check out Nexrad sites while cruising, even though going online is generally a hassle on anything but a megayacht. After all, what better way to bridge the often substantial gap between what you can see immediately around you and what the forecasters were predicting a few hours ago for a fairly wide region? So how would you like to have this almost live weather information simply overlaid on, say, a Northstar 958 chartplotter? Well, that’s exactly what a company called WSI was showing off in Miami, an impressive system called AtSea.
This article originally appeared in the June 2003 issue of Power & Motoryacht magazine.