The Mysterious Radar Echoes are No Longer Mysterious!

Earlier today the radar showed strange echoes across the Connecticut shoreline from North Branford to Salem. It was clear it wasn’t rain being picked up by the radar. How do we know that? For one, it wasn’t cloudy. Secondly, dual polarization radar products indicated (with correlation coefficient values near 0.65) these radar echoes were likely biological targets – NOT meteorological targets.

0.5º OKX Base Reflectivity and 0.5º Correlation Coefficient. Echoes are approximately 2000-3000 ft AGL.

We frequently see birds on radar around sunrise when they take off. We even see insects when they get caught up in various wind shifts. Today’s echoes were unusual in their persistence and the huge area they took up across the shoreline. Toward sunset it was clear these were indeed biological targets. The birds were flocking to the Connecticut River just before dusk.

OKX 0.5º Base Reflectivity 2145 UTC
OKX 0.5º Base Reflectity 2214 UTC
OKX 0.5º Base Reflectivity 2224 UTC. Red X marks Goose Island in Old Lyme on Connecticut River

How cool is that? On my Facebook page Paul Shipman thought the birds may be Tree Swallows that visit the lower Connecticut River this time of year. As it turns out Paul was right and tree swallows were the culprit behind the mysterious bird on radar.

According to the Hartford Courant as many as 500,000 Tree Swallows land shortly before sunset on Goose Island in Old Lyme on the Connecticut River this time of year. The radar shows the echoes disappearing  right over Goose Island. This means the Tree Swallows that had been flying near 2500 feet AGL during the day (that’s where the radar beam is) were diving under the radar beam. Here’s a close up look at where the Tree Swallows were landing in Old Lyme.

OKX 0.5º Base Reflectivity 2236 UTC.
1 – Coult Lane
2 – Route 156
3 – Tantummaheag Rad
4 – Pilgrim Landing Road
X – Goose Island (Radar sampling approximately 2700 feet AGL)

Apparently CT River Quest out of Haddam offers cruises to see the Tree Swallows landing on Goose Island around sunset. Based on what I’ve seen here on radar it must be an incredible site!

I’m excited to see if our 500,000 avian friends return tomorrow!

More Irene Pictures

The playground at Jacobs Beach in Guilford has a little too much sand on it these days. After the storm surge moved inland a tremendous amount of sand came with it. By Sunday afternoon towns were clearing sand off coastal roadways (in some cases feet of sand) while people who live near the water were shoveling sand off their driveways.

Sand Covering Jacobs Beach Playground in Guilford / Courtesy: Kara Rowell
Piles of Sand on Fairfield Beach Rd. in Fairfield

The heavy rain over inland areas also put a tremendous amount of sediment and mud into rivers and eventually into Long Island Sound. On August 30th NASA’s TERRA satellite picked up muddy rivers that appear dark brown. It’s easy to pick out the Hudson River and Connecticut River (along with the smaller tributaries). Notice that as the sediment from the flooded river flowed into Long Island Sound a plume of that sediment emerged from Old Saybrook and spread west with the current.

Courtesy: NASA Terra Satellite/MODIS