I've been watching the Central Texas bats on radar for some time now, so I've grown quite familiar with their patterns and know when they appear. A couple of times now, I've seen one of the downsides of the bats-on-radar. As actual real thunderstorms begin to move into the area, the computerized storm track detectors that filter the Nexrad radar signals and try to make sense out of them get confused.
It happened again tonight, and I was quick enough on the screen capture keystrokes to catch the bogus signal before the real weather people removed it. In the image above, that greenish patch around the Austin area is 'mostly' bats. There are some clouds running from Waco through Bryan that are real moisture with water droplets in them. But the rest of that patch running Round Rock to San Antonio is a bat signal.
The danger is that we have to put up with such false positive alerts because of the real ones. See that diamond shape half-way between Austin and Abilene? That's a real thunderstorm.
Here's a different look at the same radar signal seen through the RadarScope program. Because I've been watching the radar all day long (it's my 'screen saver' on my media server), I knew what was bats and what was weather, but it's not obvious from one screen image. And it certainly wasn't obvious to the Nexrad computer system.
I'm gradually waking up to the idea that weather radar is for a lot more things than just clouds and rain. After watching bats on the radar all week during a particularly dry atmosphere, clouds are coming back, and then today, the Bastrop fire broke out. Now, this is a forest fire, not just the grass fires we're used to. Forest fires with pine trees filled with resin that burn hot and high and send great big billowing smoke plumes up into the sky -- smoke plumes that just happen to reflect radar pulses. There are several big fires in the area this evening, but it's only the Bastrop fire that's making it's mark on the radar screen. (click image for a more detailed look)
At one point, which I neglected to capture, the image was complex with bats, and rain clouds and ground clutter and smoke plumes all in the same image. In animation mode it was interesting to see the differences. The smoke originated at a fixes point and the winds swept it off to the south, as in this image. The rain clouds moved with the wind. The bats spread out in all directions, but today their path was pushed to the south by the winds as well.
Maybe someday I'll be able to look at the images and instantly tell what I'm seeing, but it's early in the learning stages for me.
By the way, while the Radarscope program (both on iPad and Mac) give me the best images, more traditional weather radar images on Weather underground and the like also show these things, if you look for them.