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.