Tropical Storm Fred’s Moderate Rains in 3-D
The seventh tropical depression in the Atlantic Ocean was born yesterday at around 5 a.m. EDT, 160 miles south of the southernmost Cape Verde Islands and strengthened into Tropical Storm Fred by 11 p.m. EDT that night. NASA’s Tropical Rainfall Measuring Mission (TRMM) satellite captured its rainfall as it just before the depression strengthened into a tropical storm. Fred is the sixth named storm in the Atlantic Season, as one tropical depression never strengthened to get a name. The TRMM satellite, a joint mission between NASA and JAXA, the Japanese Space Agency, flew over Fred when he was a tropical depression and captured his rainfall rates. Scientists at NASA use TRMM data to create a 3-D look at the storm’s cloud heights and rainfall, which is extremely helpful in forecasting. “One of the interesting capabilities of the TRMM satellite is its ability to see through clouds with its Precipitation Radar (PR) and reveal the 3-D structure within storms such as Tropical Storm Fred,” said Hal Pierce, on the TRMM mission team in the Mesoscale Atmospheric Processes Branch at NASA’s Goddard Space Flight Center, Greenbelt, Md. Pierce created a 3-D image of Fred. He used data captured on September 7 when TRMM also got a “top down” view of the storm’s rainfall, and created a 3-D image that shows thunderstorm tops. TRMM data revealed rainfall between 20 and 40 millimeters (.78 to 1.57 inches) per hour within the storm. At 11 a.m. EDT today, September 8, Fred’s maximum sustained winds were near 65 mph, and he’s expected to strengthen into a hurricane later today. He was located at sea, 345 miles southwest of the southernmost Cape Verde Islands near 11.9 north and 28.6 west. He was moving west near 14 mph and had a minimum central pressure of 994 millibars. Fred is predicted by the National Hurricane Center (NHC) in Miami, Florida to continue gaining strength and become a minimal hurricane with wind speeds of 65 knots (~75 mph) later today. Fred isn’t expected to pose much danger because it is predicted to re-curve into the open Atlantic Ocean west of the Cape Verde Islands. |
At 11 a.m. EDT today, September 8, 2009, Linda’s maximum sustained winds are near 60 mph with higher gusts. Although she has the opportunity to strengthen a little in the next day, Linda is not expected to become a hurricane. After that, wind shear is expected to increase and Linda will move into cooler waters, two major factors that will weaken the storm. Linda is a long way from land the southern tip of Baja California. In fact, she’s about 1,320 miles west-southwest of there, near latitude 15.2 north and longitude 128.4 west. Linda is moving toward the west near 2 mph and a slow turn to the northwest should begin later today. Her estimated minimum central pressure is near 997 millibars. NASA’s infrared satellite imagery showed that the thunderstorm cloud tops in Tropical Storm Linda were somewhat scattered in the storm’s circulation. The Atmospheric Infrared Sounder (AIRS), instrument that flies aboard NASA’s Aqua satellite, captured an image of Tropical Storm Linda yesterday. AIRS Infrared imagery is false-colored and higher cloud tops of stronger storms are depicted in purple. However, the AIRS imagery from yesterday revealed that the center of Linda’s circulation was devoid of those highest, strongest thunderstorms, confirming her tropical storm status. |
