by Shannon O'Donnell, KOMO News Meteorologist Mon, June 29, 2026 at 10:56 AM Updated Mon, June 29, 2026 at 10:59 AM KOMO News Meteorologist Shannon O'Donnell explains the science behind the formation of hailstones. This graphic shows a tall thunder cloud, the place where hailstones form. (KOMO) The Treasure Valley in Idaho had a big accumulation of hail the last weekend of June due to a thunderstorm that was stuck in place near Boise, Idaho.