Over the last several days, Ophelia has meandered off of the southeast coast of the US due to weak steering currents. The system, which began as a depression over the Bahamas on the 6th of September 2005, has twice stalled out and made loops: once just east of Cape Canveral, Florida and the other further out to sea east of Georgia. Ophelia has also flip-flopped several times between a strong tropical storm and a weak Category 1 hurricane. Despite its very slow movement, which usually leads to weakening due to upwelling of cooler water, Ophelia has maintained itself as a result of warm waters and its proximity to the Gulf Stream. Ophelia is now poised to strike the Carolina coastline as a Category 1 hurricane.

The Tropical Rainfall Measuring Mission (or TRMM) satellite has been following Ophelia's progress along the East Coast. Launched in 1997 to measure rainfall over the Tropics, TRMM has proven to be a valuable tool for monitoring and studying tropical cyclones. TRMM's complement of instruments includes the TRMM Precipitation Radar (PR), the only radar capable of measuring precipitation from space, and the TRMM Microwave Imager (TMI), a passive intrument that can also measure rainfall. This first image was taken by TRMM at 17:30 UTC (1:30 pm EDT) on 12 September 2005 as Ophelia was slowing looping due east of the Georgia coastline. The image shows the horizontal rain pattern within the storm (top down view). Rain rates in the inner swath are from the TRMM PR, and rates in the outer swath are from the TMI. The rainfall pattern is overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS). TRMM shows that Ophelia has a very large eye, but the overall rain intensity, especially near the center, is weak (blue areas). At the time of the image, Ophelia was a strong tropical storm with maximum sustained winds reported at 60 knots (69 mph) by the National Hurricane Center.

In the second image taken at 12:24 UTC (8:24 am EDT) on September 14th, the northwest part of the eyewall is already over Cape Fear on the North Carolina coast. The overall storm structure appears little changed from the previous image with Ophelia still having a very large eye. However, the rain pattern is now more substantial with more areas of moderate rain (green areas). The pattern is also more symmetric (i.e., evenly distributed around the storm). At the time of this image, Ophelia's winds were sustained at 70 knots (81 mph).

The final image was taken at the same time and shows the height of the precipitation columns within Ophelia (as defined by the 15 dBZ isosurface) with a cutaway view through the southern part of the eye. The large eye is easily visible in the center along with the area of intense rain in the southwest corner of the eye (dark red area). However, there are no tall towers surrounding the eye that might indicate imminent strengthening.

TRMM is a joint mission between NASA and the Japan Aerospace Exploration Agency (JAXA).

Images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC).