Tuesday morning, June 17th, Jack KM4ZIA will be launching a large HAB (High-Altitude Balloon) and two picoballoon launches from Youth On The Air (YOTA) Camp in Thornton, Colorado.
Video here:
https://photos.app.goo.gl/R1dka9TgZeznahTBA

The large HAB will be launched at 8:30 MDT (Denver), and it will carry a voice beacon that transmits a voice message every minute at 146.550 MHz FM. The voice beacon directs you to go to aprs.fi to track the balloon's other payload W4SDR-12, which is a 144.390 MHz APRS SkyTracker from Bill Brown, WB8ELK.  Hams within a few hundred miles of Denver should hear it.

We expect the HAB to ascend to 100,000 feet or so before it pops, and then it will take a parachute ride back to earth. The payload recovery team is the Edge of Space Sciences (EOSS) group.

The picoballoons will be launched sometime near 1PM MDT. Both are 1 meter balloons that will rise to a float altitude of about 40,000 feet. 

The picoballoon callsigns are:

W0Y-1, which is operating on 15 meters.
W0Y-11, which is operating on 10 meters.

Both can be tracked in real time at https://www.wsprnet.org/drupal/wsprnet/map or at https://aprs.fi/#!lat=39.79450&lng=-105.09530.