06 July 2017

Tropical Depression Four forms far from land

The disturbance I wrote about yesterday was upgraded to Tropical Depression Four early Thursday morning.  It is located about halfway between the Lesser Antilles and the African coast in the deep tropics.

Enhanced satellite image of the deep tropical Atlantic.  Orange and red hues indicate dry dusty air, while blue and green hues indicate more moist air. (EUMETSAT)

Zoom-in view of TD4.  The fine whispy cirrus clouds radiating out from the center is a clue that upper-level winds are not very strong.
Although the vertical wind shear has relaxed for now, it is becoming surrounded by dry mid-level air which squelches thunderstorm activity, so it is not expected to develop too much more.  Some models indicate it could attain tropical storm status, but the National Hurricane Center keeps it as a Depression through the next three days before dissipating.


Again, if it gets named it would be Don, and would be about seven weeks ahead of the average date of fourth named storm formation.