Conditions Supporting Funnel Cloud Development in Alaska

• 作者: Katja Friedrich Nicole M?lders Richard Thoman Sebastian Schmidt Stanley G. Edwin
• 来源期刊: 大气和气候科学(英文)
• 学科: 地球科学
• 关键词: Alaska FUNNEL CLOUDS FUNNEL CLOUD CLIMATOLOGY Similarity Retrieval Algorithm MESOSCALE FORCING for FUNNEL CLOUD Formation in Alaska
• 年，卷（期）: 2017,（2）
• 页码范围: 223-245
• 页数: 23页
• 分类号: P4

摘要

The characteristics and climatology of funnel clouds in Alaska were examined using operational radiosondes, surface meteorological observations, and reanalysis data. Funnel clouds occurred under weak synoptic forcing between May and September between 11 am and 6 pm Alaska Daylight Time with a maximum occurrence in July. They occurred under Convective Available Potential Energy >500 J·kg-1 and strong low-level wind shear. Characteristic atmospheric profiles during funnel cloud events served to develop a retrieval algorithm based on similarity testing. Out of more than 129,000 soundings between 1971 and 2014, 2724, 442, and 744 profiles were similar to the profiles of observed funnel cloud events in the Interior, Alaska West Coast, and Anchorage regions. While the number of reported funnel clouds has increased since 2000, the frequency of synoptic situations favorable for such events has decreased.