NASA satellites provided a rare glimpse into the structure of Subtropical Storm Arani, which was located about 1,700 miles (2,735 kilometers) east of Bermuda.
Arani developed from a non-tropical low-pressure system that was located about 1,800 miles east of Bermuda. On September 24, the National Hurricane Center (NHC) issued advisories on Arani, classifying it as a subtropical storm.
At 5 a.m. EDT (0900 UTC) on September 25, the center of Subtropical Storm Arani was located near latitude 30.8 degrees north, longitude 50.2 degrees west, approximately 1,700 miles east of Bermuda. Arani was moving to the southeast at 8 mph (13 kph).
Arani has maximum sustained winds of 65 mph (105 kph), with higher gusts. The estimated minimum central pressure is 1003 millibars.
Arani is expected to gradually strengthen over the next few days. However, it is not expected to become a hurricane. Arani is expected to remain over the open ocean and dissipate by early next week.
NASA's Aqua satellite passed over Subtropical Storm Arani on September 25 at 1:05 p.m. EDT (1705 UTC). The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on board Aqua provided a visible-light image of the storm. The image showed that Arani had a well-defined center with numerous towering thunderstorms.
The MODIS image also showed that Arani had a large area of cold cloud tops. Cold cloud tops are an indication of strong convection and heavy rainfall.
NASA's TRMM satellite followed Aqua about an hour later. The TRMM satellite's Microwave Imager (TMI) instrument provided a microwave view of the storm. The TMI image showed that Arani had a large area of heavy rainfall. The rainfall was estimated to be as heavy as 2.5 inches (6.3 centimeters) per hour in some areas.
Arani is a rare type of storm. Subtropical storms are typically found in the western Atlantic Ocean, but they can also occur in the eastern Pacific Ocean and the Indian Ocean. Subtropical storms have characteristics of both tropical cyclones and extratropical cyclones. They have the warm-core structure of a tropical cyclone, but they also have the cold fronts and low-pressure centers of an extratropical cyclone.
Subtropical storms can be dangerous, even though they are not as strong as hurricanes. They can produce heavy rainfall, flooding, and high winds. Arani is expected to produce heavy rainfall and gusty winds as it moves over the open ocean.
