Portal:Tropical cyclones/Anniversaries/April/20
![](http://upload.wikimedia.org/wikipedia/commons/thumb/e/ed/Isa1997peak.jpg/100px-Isa1997peak.jpg)
April 20
- 1997 - Typhoon Isa (pictured) reached its peak intensity with winds of 270 km/h (165 mph) to the west of the Mariana Islands. Isa passed south of Guam, where it caused beneficial rainfall.
- 2017 - Tropical Storm Arlene intensifies from a subtropical depression, making it one of only two systems in the Atlantic to form in the month of April.