Bryan Norcross: Tropical disturbance over the eastern Atlantic to watch

As a result of the negative factors impinging on the tropical belt, the National Hurricane Center is giving the disturbance a low chance of developing before it reaches the Caribbean islands around mid-next week.

UPDATED at 9 a.m. EDT Thursday

A broad swatch of disturbed weather in the far eastern Atlantic is noted by the National Hurricane Center as an area to watch over the next several days. A diffuse African disturbance is moving west, but it's plowing through a semi-permanent area of thunderstorms called the Intertropical Convergence Zone or ITCZ.

The ITCZ is caused by the change in the dominant wind direction across the equator due to the spinning of the Earth. The winds blow east-to-west north of the equator and west-to-east to the south. These two natural wind regimes "converge" in a band to the north of the equator in the summer. This convergence zone produces the line of thunderstorms we see near the equator around the Earth.

As our disturbance of interest moves through the ITCZ, it will get some additional spin from the converging wind regimes from the north and south. But the wind flow in the vicinity of the disturbance is also disrupted by other clusters of thunderstorms nearby. So it's usually not a conducive environment where a system can develop.

Over the weekend and into next week, if the disturbance makes it farther west, it will likely have to deal with dry air and Saharan dust, another deterrent to development.

As a result of the negative factors impinging on the tropical belt, the National Hurricane Center is giving the disturbance a low chance of developing before it reaches the Caribbean islands around mid-next week. 

To the north, Tropical Storm Don is still chugging along in its giant loop toward oblivion in the cold North Atlantic. Winds have increased a bit as it has tracked over warmer water, but there's a cold ocean ahead.

Don should be toast by early next week. There's no threat to land.

Otherwise, nothing is pending. The long-range computer models show a more typical summer pattern, so there's some hope, at least over Florida, that more ocean breeze will eventually take the edge off the heat and humidity.

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