Low-level jets were observed during Project Koorin (a special 29 days of hourly planetary boundary layer data) at Daly waters, in the winter of 1974. Time-height cross-sections show a double jet structure in the mean, and on two days jet speeds of over 20 m/s when the tightest pressure gradients occured. Twenty years of routine morning pilot balloon flights reveal the occurrence of one jet with a wind speed greater than 30 m/s.
S.C. Allen (Sun,) studied this question.