easterly wave

meteorology

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July 16, 2026

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An easterly wave is a region of low atmospheric pressure that moves from east to west. These waves are crucial in meteorology as they are the precursors to tropical cyclones in the Atlantic and eastern North Pacific.1

An easterly wave is characterized by a weak circulation and is typically found at an altitude of about 3,600 meters (12,000 feet), extending horizontally for approximately 2,400 km (1,500 miles). When favorable conditions are present, such as warm ocean waters (at least 26.5°C or 80°F to a depth of 50 meters), an easterly wave can intensify and contract, eventually developing into a tropical storm and then a tropical cyclone. These conditions include a pre-existing atmospheric circulation, rapid cooling with height to support deep convective clouds, and sufficient humidity in the middle atmosphere.12

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tropical cyclone
Favourable wind systems
This jet generates easterly waves—regions of low atmospheric pressure that have a maximum intensity at an altitude of about 3,600 metres (12,000 feet) and a horizontal extent of about 2,400 km (1,500 miles). Most of the tropical cyclones in the Atlantic and eastern North Pacific begin as easterly…
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This jet generates easterly waves—regions of low atmospheric pressure that have a maximum intensity at an altitude of about 3,600 metres (12,000 feet) and a horizontal extent of about 2,400 km (1,500 miles). Most of the tropical cyclones in the Atlantic and eastern North Pacific begin as easterly…
Read More