Welcome to the Tropical Wave page of Hurricane Alley.

Disclaimer:
All the information on this site is published as "real-time" as possible, but it is important to remember that the only "official" source of information is the National Hurricane Center. Decisions concerning life or death, property, and such should not be made based solely on the information found on this site. Listen to your local authorities when conditions are life-threatening or there is possible loss of property.

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If there is a storm or an invest click on the storm area in the graphic to go to the information page.
The yellow dashed lines are tropical waves
The brown area is the Saharan Air Layer/dust - the darker the color, the thicker the dust
The wave numbering is not "official", but based on the NHC's defined waves during their TWD issuances

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A tropical wave in the Atlantic basin is an area of lower pressure in the tropics that evolves primarily from clusters of thunderstorms over Africa, although they have been known to form in the Caribbean as a result of other atmospheric mechanisms. The African variety form in the lee, or down wind area of the Ethiopian Highlands of eastern Africa. They become large areas of thunderstorms which migrate westward across central Africa. This formation takes place as a result of the meridional gradient of potential vorticity changing sign over Africa near 700 mb during the warm season. The resulting thunderstorm complexes move off the west coast of Africa near Senegal, or about 10 degrees north latitude, and move westward across the Atlantic. Once these areas of low pressure enter the Atlantic we call them tropical waves. Tropical waves have a unique weather pattern. When you "analyze" a tropical wave on a weather map it looks like an inverted area of low pressure or "upside down V" that bulges northward along a north/south axis. Often this axis is oriented northeast to southwest. A typical tropical wave has light northeast winds, sinking air and relatively nice weather to the west or what is termed "ahead of the wave axis". To the east of the wave axis there are gusty southeast winds, rain, and thunderstorms, or what is termed "behind the wave axis". Sometimes these waves are hard to track due to the presence of dry air or wind shear. Some waves are embedded in dry air filled with dust from Africa. This dust causes the temperature at about 10.000 feet to become warmer. This is then know as a temperature inversion. A temperature inversion, if strong enough will prevent clouds and showers from forming. So, some tropical waves have very few clouds when they are involved with dry air and a strong temperature inversion. The waves that have a large area of clouds and thunderstorms are the ones that need to be to watched closely for potential development. The more thunderstorms there are associated with a wave, the more potential it has to become an organized tropical system. Almost 85% of all tropical storms and hurricanes in the Atlantic and Eastern Pacific basins form from the African tropical waves. In a typical tropical season an average of 80 - 100 tropical waves track across the Atlantic basin.