本文分析民國八十五年九月廿五日臺灣西北部的一次午後強烈雷雨個案。該系統 之大雨中心首先到達臺南，而後沿中央山脈西側北移。資料顯示，當時南中國海有一熱帶低 壓向西移動，而大陸上則有微弱冷空氣自華北東部沿海向南推，並逐漸接近本省北部，這就 構成了中緯度鋒面與熱帶系統逐漸匯集的局面。在此狀況下，由熱帶低壓東側北上之對流雲 胞，於臺灣海峽南部右偏，先遇上中央山脈，而後又與在北部近海的鋒面合併，致局部大雷 雨由本省西南部開始，並在北移中增強其勢力。透過分析傳統與衛星雲圖等資料可知，此次 降水系統之發展以及影響地區與梅雨季豪大雨類似，均受制於鋒面、熱帶對流系統、以及地 形三者間的交互作用；但在季節上而言，與大陸及韓日所稱「秋霖」是一致的。其次，由雷 雨發生時間與地面溫度變化可知，午後熱對流所引起之局部輻合，亦扮演重要角色；而此種 作用可能是所謂「秋霖」與梅雨系統中最不相同的機制（之一）。
On 25th of September, 1996, severe thunderstorms occured on the west coast of Taiwan. The center of heavy rain first occured in Tainan area. Then, it moved along the west slope of the Central Mountain Range (CMR, hereafter) toward north tip of the island. From our re-analysis we found that the cloud cluster propagated from a tropical depression, located at south west of Taiwan Strait, met the CMR first, then merged with a weak cold front is the main reason for the line convection and heavy rain. The condition seems like that in the Mei-Yu season. But, diurnal heating along the south western slope of CMR might had played much important role in this case then in the cases of Mei-Yu season. In Northern China, according to the period, this phenonmenan is called "Autuman Reuin" on "Chu-Yu".
