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At a Glance Saharan dust and sinking air have been keeping the Atlantic quiet.

Increasing rising air might arrive by the end of the month.

An uptick in tropical activity could also follow.

Saharan dust and increased wind shear has kept the tropics at bay since Beryl and Chris formed earlier in July, but a new atmospheric tide might increase tropical activity toward the end of the month.

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Activity has been sunk in recent days, in part, by the Madden Julian Oscillation's (MJO) suppressed phase. The lack of recent activity is also because of the dust infiltrating the skies from Africa to Texas. Clouds across the tropics are having a difficult time growing beyond the small cottonball variety.

This could change as August approaches, as winds aloft might become more favorable as the MJO's enhanced phase swings around to the eastern Pacific and eventually the Atlantic.

<img class="styles__noscript__2rw2y" src="https://dsx.weather.com/util/image/w/mjo_curr.jpg?v=at&w=485&h=273&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0" srcset="https://dsx.weather.com/util/image/w/mjo_curr.jpg?v=at&w=485&h=273&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0 400w, https://dsx.weather.com/util/image/w/mjo_curr.jpg?v=ap&w=980&h=551&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0 800w" > The enhanced phase of the MJO, in green, is moving eastward slowly into the eastern Pacific. (Climate Prediction Center) (Climate Prediction Center)

This active phase has, in part, produced two tropical cyclones in the western Pacific and several active tropical waves in the central Pacific in the last week.

This phase is expected to move eastward into the tropical eastern Pacific and western Atlantic, including the Caribbean, to end the month and begin August.

Some unknowns still exist for a forecast two to three weeks into the future: how must eastward advancement the enhanced phase of the MJO will make and how robust it will be. Some climate models suggest it may not reach the heart of the tropical Atlantic until later in August.

(MORE: 2018 Atlantic Hurricane Season Expected to Be Less Active, According to CSU )

This period of favorable phase MJO might also coincide with another kind of atmospheric disturbance called a Kelvin wave . This wave moves eastward on the equator but is often a precursor to tropical cyclone birth by a day or two. The next Kelvin wave is set to arrive in the Caribbean and western Atlantic during the last week of the month.

These large-scale disturbances are only helpful hands in the tropics, however. Favorable weather conditions like low wind shear, a lack of African dust and a tropical wave or two in the southern Atlantic, Gulf of Mexico and/or the Caribbean are needed to get a tropical system going.

The next window for tropical activity may open after July 25 and into early August if conditions align. With a cold front slowly progressing southward near the U.S. East Coast, a subtropical system could spawn off that boundary, but chances are low this will occur.

If a system develops, it will have a better chance of organizing and strengthening as the favorable phases of the MJO and Kelvin wave pass over.

What is the Madden Julian Oscillation?

The MJO is a large-scale tropical disturbance that moves eastward around Earth every 30 to 60 days with enhancement and suppressant phases occurring on opposite sides of the planet.

During the summer months, enhanced phases are watched for increasing thunderstorm activity, including in the tropics. These phases involve upper-level winds that diverge aloft, causing air below to rise, making it easier for thunderstorms to blossom.

This wave of activity does not by itself create thunderstorms, tropical waves or hurricanes, but it does, however, make the atmosphere more hospitable for these features.

<img class="styles__noscript__2rw2y" src="https://dsx.weather.com/util/image/w/mjo_explained_noaa.jpg?v=at&w=485&h=273&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0" srcset="https://dsx.weather.com/util/image/w/mjo_explained_noaa.jpg?v=at&w=485&h=273&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0 400w, https://dsx.weather.com/util/image/w/mjo_explained_noaa.jpg?v=ap&w=980&h=551&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0 800w" > Airflow within the Madden-Julian Oscillation (Climate Program Office/NOAA) (Climate Program Office/NOAA)

(MORE: The MJO's Impact on Hurricane Forecasting )

The suppressed phase of the MJO causes thunderstorm suppression. Upper-level winds become convergent, which causes air to sink and warm, making thunderstorm development more difficult.

This signal can also be muddied by other climate signals, such as El Niño, easterly wind bursts and upwelling from previous storm systems, and also by weather patterns such as Saharan dust outbreaks and dips in the jet stream.

This combination of signals can help produce several storms as the disturbance moves through in some parts of the world. It can also create weeks of drier weather in the suppressed phase.