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Satellite Sees Tropical Storm Julia Getting ‘Dusted’

September 20, 2010

Dust has been blowing into the Eastern Atlantic Ocean from Africa’s Saharan Desert, and a NASA satellite captured some of that dust east of Tropical Storm Julia.

NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on the Terra satellite captured a visible image of Tropical Storm Julia on Sept. 18 at 13:50 UTC (9:50 a.m. EDT) and noticed a large area of Saharan dust over the Atlantic Ocean, to Julia’s east.

On Sept. 20 at 5 a.m. EDT, Julia was still holding on to tropical storm status with maximum sustained winds near 45 mph. Julia was located about 1,165 miles west of the Azores Islands near 35.5 North and 47.9 West. Julia is moving east-northeast near 9 mph and is forecast to speed up. Julia’s estimated minimum central pressure is 998 millibars.

In addition to dealing with Saharan dust, Julia is dealing with wind shear created by massive Hurricane Igor far to her west. That westerly wind shear continues to push Julia’s strongest convection (rapidly rising air that forms the thunderstorms that power her) to the east of Julia’s center of circulation. When a tropical cyclone doesn’t “stack up” line an upright column, it loses its uniform spin, and tends to weaken.

The National Hurricane Center expects Julia to fade into a remnant low in a day or two. Computer models show two different scenarios after that, as some see Julia could be absorbed in the massive circulation of Hurricane Igor, while others keep Julia separate and becoming extratropical before dissipating over cooler waters.

Meanwhile, as the curtain begins to drop on Julia in the eastern Atlantic, another low pressure system is in the wings to create its own show. There’s a low about 400 miles west of the Cape Verde Islands that is showing signs of organization today. It’s moving northwestward and has an 80% chance of becoming a tropical depression in the next 48 hours. That low is one that NAA satellites are keeping a close eye on.

Image Caption: NASA’s MODIS instrument on the Terra satellite captured a visible image of Tropical Storm Julia on Sept. 18 at 13:50 UTC (9:50 a.m. EDT) and noticed a large area of Saharan dust over the Atlantic Ocean, to Julia’s east (right). Credit: NASA Goddard/MODIS Rapid Response Team

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