The SPC awaited data from morning balloon soundings. Twice each day at 0 and 1200 Greenwich Mean Time—Zulu time, or Z for zero, to meteorologists—weather stations worldwide sent aloft six-foot latex balloons with radio transmitters attached. In Norman, National Weather Service forecasters released their balloons at 7:00 a.m. and 7:00 p.m., central daylight time.
