Doppler Radar Detects Object That Turns Out To Be Birds, Again

A mysterious radar return that appeared on a National Weather Service dual-polarization Doppler radar in central Texas, briefly sparking speculation among forecasters about an unusual meteorological phenomenon, has been identified as birds. Again. The return appeared at approximately 6:43 p.m. on Wednesday as a diffuse, expanding ring of reflectivity emanating from a point source south of San Antonio. For approximately twelve minutes, forecasters debated whether the signature represented an outflow boundary, a gravity wave, or what one junior forecaster described as "something we've never seen before." "It was birds," confirmed senior forecaster Angela Reflectivity. "It's always birds. Every time we think it might be something interesting, it's birds. Starlings, specifically, departing their roost in a radial pattern. The correlation coefficient was wrong for precipitation from the start, but we got excited." Dual-polarization radar, which measures the shape and behavior of objects in the atmosphere, can theoretically distinguish between raindrops, hail, insects, and birds. In practice, the signatures occasionally overlap, producing what Reflectivity describes as "five minutes of false hope." "The differential reflectivity was negative, which rules out rain," she explained. "The correlation coefficient was below 0.85, which suggests non-meteorological targets. I knew in my head it was birds. But in my heart, I wanted it to be a mesoscale gravity wave." The forecast office has identified bird roosts on radar seventeen times this season, along with four instances of insect blooms, two suspected chaff releases from a nearby military base, and one return that remains officially classified as "unknown" but is widely believed to have been a large flock of pelicans. "We track them all in a spreadsheet," Reflectivity noted. "It's not science at that point. It's birdwatching with a $2 million radar."