Tropical Depression 4 now a small tropical storm named Colin

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Credit: NASA GOES Project

NASA JPL, Ed Olsen

The fourth Atlantic tropical depression became Tropical Storm Colin early in the morning today, August 3 and NASA and other satellites are keeping tabs on it. A GOES-13 satellite visible image at 1145 UTC (7:45 a.m. EDT) on August 3, showed Tropical Storm Colin as a compact area of clouds in the central Atlantic Ocean. NASA infrared imagery from the Aqua satellite has watched Colin's convection increase over the last day, indicating the storm's strengthening to a tropical storm. GOES-13 or the Geostationary Operational Environmental Satellite monitors U.S. east coast weather and is operated by NOAA. The NASA GOES Project at the NASA Goddard Space Flight Center in Greenbelt, Md. uses GOES data to create images and animations.

Colin is a small tropical storm. Tropical storm force winds extend outward up to 35 miles from the center. At 5 a.m. EDT, the center of Tropical Storm Colin had maximum sustained winds near 40 mph with higher gusts. Some additional strengthening is forecast during the next 36 hours or so. Colin was located near latitude 14.0 north and longitude 47.2 west and has an estimated minimum central pressure of 1006 millibars.

Colin is moving toward the west-northwest near 23 mph and this general motion is expected to continue for the next day or two. Colin is over open waters and not expected to affect any land areas in the next couple of days. Colin is forecast to pass well to the northeast and north of the Leeward Islands late Wednesday and early Thursday.

On August 2 at 11:59 a.m. EDT, NASA's Aqua satellite passed over the storm when it was still a tropical depression. The Atmospheric Infrared Sounder (AIRS) instrument captured an infrared image that showed some strong convection and high, cold cloud tops around Tropical Depression 4's (TD4) center. Seventeen hours later TD4 strengthened into Tropical Storm Colin. Infrared imagery on August 3 showed a curved band of showers and thunderstorms wrapping halfway around the circulation over the western semicircle of the storm.

What lies ahead for Colin? Colin is expected to be in a good environment that will allow for some strengthening. That good environment consists of moderate to weak vertical shear and anti-cyclonic upper-level (in the upper atmosphere) flow over the next 36 hours or so. After that, the westerly wind shear is forecast to increase and that should begin to weaken Colin.

In addition to Colin, there's a second area of low pressure that forecasters are watching. That other area is one of clouds with showers and thunderstorms over the southeastern Caribbean Sea and the adjacent land areas. That low is associated with a westward-moving tropical wave. Currently, however, there are currently no signs of organization, so any development will be slow because the system is close to land. There is a 20 percent of this system becoming a tropical cyclone during the next 48 hours.

Source: NASA/Goddard Space Flight Center