BRAINERD, MINN. - If your spare time is spent out-of-doors, whether you are hunting, fishing, birding or otherwise taking in some of what this state has to offer, chances are you are also a weather watcher.
Computers and the World Wide Web have provided us instant access to up-to-the-minute weather information, including the satellite views and radar. The same information can be accessed via cell phone. Now a person can actually add a current weather map atop your favorite Google view.
A few years ago, just after dark, while viewing a NEXRAD radar website I noticed unusual green blobs surrounding most cities. Since on the radar site I was viewing light rain shows up as green, I thought at first I was looking at rainfall. But why was it raining only in neat little circles surrounding various cities? That must be what weather forecasters refer to as "ground clutter," I thought. Then when I put the weather map into motion I noticed the green blobs grew after sunset. Why, I thought, would radar detect more ground clutter after dark?
Curiosity got the better of me. I did some checking and found the green blobs did not indicate light rain or ground clutter -- but instead migrating birds.
I now frequently monitor bird migration and movements via the latest NEXRAD radar: It's interesting and fun. I'm amazed that few people actually know about it.
My favorite site for viewing NEXRAD radar is Weather Underground, found at www.wunderground.com. Once I'm on the home page, I click on "Regional Radar" just below the banner at the top of the page and then I choose the region of the country I wish to view. Just about all the weather websites feature NEXRAD radar -- you might find you prefer a different site, so try the many options available.
NEXRAD stands for the "next generation of radar." There are roughly 160 NEXRAD radar stations scattered across the United States. Large-scale bird migration and feeding flight patterns can be monitored via NEXRAD, and you don't have to be a weather scientist to decipher the radar returns.
Each NEXRAD radar -- for various technical reasons -- is able to detect birds out to about a 20-mile radius from the station. Thus the green blobs I wrote about earlier. Unfortunately, that leaves a lot of open spaces in between NEXRAD sites where bird movement goes undetected.
In recent years, ornithologists have used NEXRAD radar to monitor seasonal and daily flight patterns of birds as well as important migration stopovers. NEXRAD has aided scientists in mapping important roosting sites for purple martin, a bird that had been in decline and is of special concern.
How can we -- birders, hunters, nature enthusiasts -- use NEXRAD to our advantage?
Each spring, I take a trip to South Dakota to photograph the waterfowl migration. Starting in early March, I monitor the NEXRAD radar watching for signs of birds moving north. Aberdeen, S.D., has a NEXRAD radar, and when I see my computer monitor lit up with green dots around this town, I know it's time to go west.
Some birders use NEXRAD to predict "fallouts," a term used to describe days when major migration stopovers occur.
Be sure to test the various functions of your NEXRAD site of choice. Click on radar "loop" to put the map in motion. A 24-hour loop is especially fun to watch.
The northward movement of warblers and other late migrants is happening now so watch for that via NEXRAD in the coming days. Most songbirds migrate at night, so monitor your favorite NEXRAD site just after dusk. If the weather is right -- calm or with a southerly wind -- watch the radar returns grow as darkness takes over. The same return will diminish at dawn as the nighttime migrants settle in for a day of rest and feeding.
Then it's time to go afield, because as fascinating as observing migration on radar can be, it is impossible to top actually being out there.
Bill Marchel, an outdoors columnist and photographer, lives near Brainerd.