After the inspection of the amount of rainfall in a low-pressure region of Atlantic Ocean located in the southwest of the Azores, it was declared as the Subtropical Depression One on 19 April. By 20 April, it was converted into Atlantic Ocean Tropical Depression 1 that was measured by NASA's GPM satellite.

As written in Phys.org, the subtropical depression was forming in the North Atlantic Ocean on 19 April 11 AM EDT before it turned into the Atlantic Ocean Tropical Depression 1 on 20 April. At the time of subtropical depression, the Global Precipitation Measurement Mission, known as GPM satellite flew over the area and successfully marked the places that had the heaviest rainfall.

Information gathered by GPM's Microwave Imager (GMI) and Dual-Frequency Precipitation Radar (DPR) instruments April 19, 2017, at 0746 UTC (3:46 AM EDT) demonstrated direct to substantial precipitation inside the low-pressure region. DPR uncovered that rain was falling at a rate of more than 30 mm (1.2 inches) every hour in showers situated toward the east of the low's focal point of course. GPM's radar (DPR Ku Band) likewise demonstrated that a couple storms turning around the low center focus were dropping precipitation turning into an Atlantic Ocean Tropical Depression 1.

EurekAlert reported that GPM is a joint satellite mission amongst NASA and the Japan Aerospace Exploration Agency, JAXA. Before the formation of Atlantic Ocean Tropical Depression 1, the National Hurricane Center (NHC) noticed the area as a sub-tropical low-pressure area. The main difference between the subtropical and tropical cyclone is the temperature structure of the storm.

The National Hurricane Center (NHC) predicts that the Atlantic Ocean Tropical Depression 1 will turn into a leftover low-pressure area later on April 20 and wind up plainly consumed by a bigger low around evening time or early Friday, April 21. The tropical depression would be consumed by a bigger low-pressure region.