Torrential rainfall and rapid snowmelt in April 2017 caused deadly floods in northwestern Iran. An atmospheric river (AR), propagating across the Middle East and North Africa, was found responsible for this extreme event. The snowmelt was triggered by precipitation and warm advection associated with the AR. Total satellite-based rainfall for April 2017 was moderately below normal, suggesting that a heavy flood can happen during dry years. The AR was fed by moisture from the Mediterranean and Red Seas. Despite its adverse societal consequences, this event was beneficial to the recovery of the desiccating Lake Urmia. The impacts of this AR were not limited to flooding; it also facilitated dust transport to the region. This distinct characteristic of the ARs in the Middle East is attributed to major mineral dust sources located along their pathways. This event was reasonably predicted at 7-day lead time, crucially important for successful early warning systems.

中文翻译：

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一条尘土飞扬的大气河流给中东带来洪水

2017 年 4 月的暴雨和快速融雪在伊朗西北部造成了致命的洪水。一条横跨中东和北非的大气河流 (AR) 被发现是造成这一极端事件的原因。融雪是由与 AR 相关的降水和暖平流引发的。2017 年 4 月基于卫星的总降雨量略低于正常水平，这表明干旱年份可能会发生大洪水。AR 由来自地中海和红海的水分供给。尽管造成了不利的社会后果，但这一事件有利于干燥的乌尔米亚湖的恢复。这种 AR 的影响不仅限于洪水；它还促进了向该地区输送粉尘。中东 AR 的这种独特特征归因于位于其路径沿线的主要矿物粉尘源。