To improve short-range forecasting of gusts within cold front in winter, wind structures surrounding cold-frontal rainbands were investigated using a single doppler radar, a doppler sodar, and a rawinsonde system at the Komatsu airport in the Hokuriku district of Japan. Four rainbands were examined on December 22, 1996 and one on January 1, 1997. They were designated Rainbands a, b, c, d, and e.
Wind structures in the back of Rainbands b and e were apparently similar to a density current, and many gusts were observed around the rainbands for a period of about 40 minutes. Around Rainbands c and d, wind structures were similar to a much smaller density current and fewergusts were observed for a period of only ten minutes. No wind structuresresembling a density current were apparent around Rainband a, where only one gust was observed.
The gust accompanying Rainband a was observed just before strong precipitation at the Komatsu airport in a small strong wind area occuring near the ground surface in front of an intense radar echo. The strong wind area is, therefore, considered to be formed of outflow from dissipating Rainband a. The first gust of Rainbands b and e was also observed just before strong precipitation or the arrival of an intense radar echo at the Komatsu airport and they are expected to be strongly influenced by outflow from each rainband. Many gusts were, however, observed in a strong undercurrent at the rear of each rainband. Around Rainbands c and d, a few gusts were also observed in the strong undercurrents at the rear of each rainband, although the areas of strong undercurrents were small.
Rainbands b, c, and d approached the Komatsu airport in sequence. The tail of the strong undercurrent at the rear of Rainbands b and c was lifted upward by the subsequent Rainbands c and d. No gust was observed in the area where the strong surface undercurrent was lifted. Rainbands d and e had no rainband behind them, and their strong undercurrents were not lifted but gradually weakened near the sea surface, with no gust observed thereafter.
The 8th Conference on Aviation, Range, and Aerospace Meteorology