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1st African Tropical Wave of 2012 with a Chance of Development

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The Atlantic basin has been relatively quiet so far this year.  While four tropical storms formed prior to July (the earliest on record), all of them were weak and short-lived since they formed on the western side of the basin.  This situation is largely due to higher wind shear than normal and a strong high pressure region, which pushes air toward the ground instead of lifting it.

The National Hurricane Center in Miami, FL has issued an outlook for an area of disturbed weather currently centered 1,150 miles southwest of the Cape Verde Islands.  The center is giving Invest 99L a 20% chance of tropical cyclone development within the next 48 hours – still pretty low, which means the system bears watching as it makes its way across the Atlantic over the next week.

The system is near 9°N 36°W.  9°N (click for a decent IR satellite image), which is relatively close to the Equator as far as tropical systems are concerned.  Disturbed weather at this latitude have a hard time acquiring the angular momentum necessary to grow into a cyclone.  If the system were to angle northwestward for a few days, it would stand a much better chance of development by the time it reached the Lesser Antilles.

Wind shear is minimal in the area (5-10knots).  Sea-surface temperatures have been warm enough for tropical cyclone development for months, so that’s not an issue with this system.

The GFS ensemble members project Invest 99L to move through the eastern Caribbean island chain sometime next week.  The specific timing for this will have to wait until we’re much closer in time.


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