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When available, the latest Free Text Message (FTM) from each of our local radars (EWX, DFX, and GRK) will be listed below. These messages provide status information for known issues, maintenance downtime, etc.
No recent Free Text Message for KEWX
No recent Free Text Message for KDFX
No recent Free Text Message for KGRK
During summer there are some unique images that show up on local weather radars that have nothing to do with the weather. Instead, they are millions of bats from local caves and urban areas leaving their shelters each evening to spend the night feasting on the bugs of South Central Texas. These bats then return to their shelters around dawn, again showing up on radar. A combination of the sheer number of bats across the area, the sensitivity of the radars to biological targets, and the close proximity of these caves and urban areas to our three main radars all contribute to the radar images of the bats.
When the bats leave the caves or the bridges, they circle as they gain altitude. This appears on the radar as a circle or doughnut that starts small and then gets progressively larger. For Bracken Cave, due to the number of bats leaving the cave and how close it is to the KEWX radar (less than 20 miles), the signature can show up on radar as a 40 to 50 dBZ reflectivity image. These values are typically seen during a moderate shower or weak thunderstorm.
Left: Bats Leaving Bracken Cave on the Evening of July 9, 2020 around 7pm.
Right: Bats Returning to Bracken Cave on the Morning of July 10, 2020 around 7am.
To learn more about the Mexican free-tailed bats that inhabit the area, visit the Bat-Watching Sites of Texas website from the Texas Parks and Wildlife Department. This site contains information about the bats, and it describes many of the area caves and bridges inhabited by large bat colonies. Bat Conservation International helps protect Bracken Cave along the Bexar/Comal County line, housing the largest bat colony in the world, and has additional information on their website. If you have radar questions about the bats on any of the Central Texas radars, contact aaron.treadway@noaa.gov.
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