Tropical Depression Nine formed yesterday, Sept. 8 in the far eastern Atlantic, and NASA's Aqua satellite saw it strengthen into Tropical Storm Humberto today, Sept. 9 at 5 a.m. EDT. As that storm strengthened, the remnants of the once-tropical-storm Gabrielle continued to struggle near the Bahamas as NASA's HS3 mission investigated.
Tropical Storm Humberto is affecting the Cape Verde Islands, so there's a tropical storm warning in up for the southern islands of Maio, Santiago, Fogo, and Brava.
NASA's Aqua satellite passed over Tropical Storm Humberto hours before it was designated a tropical storm, and the Atmospheric Infrared Sounder instrument called "AIRS" captured infrared data on the storm. The AIRS data showed that some strong thunderstorms had developed around the center of circulation that were acting as a "heat engine" for the storm and strengthening it. Cloud-top temperatures of those powerful thunderstorms were colder than -63F/-52C, and forecasters at the National Hurricane Center expect Humberto to continue strengthening in the short term. The image also showed that the most powerful thunderstorms, the ones with the coldest cloud top temperatures, were just south of the Cape Verde Islands at the time Aqua flew overhead. Humberto has since moved closer to some of the southern islands bringing rain and gusty winds today.
NASA's Hurricane and Severe Storms Sentinel or HS3 mission gathered data over Gabrielle's remnants over the weekend of Sept. 7 and 8. NASA's Global Hawk 872, or NASA 872 departed from NASA's Wallops Flight Facility, Wallops Island, Va. on Saturday, Sept. 7 at 8:07 a.m. EDT and flew over the remnants of Gabrielle as it lingered north of the Dominican Republic. NASA 872 dropped dropsondes and took various measurements of the remnants during its flight.NASA 872 ended flight upon landing back at NASA's Wallops Flight Facility, Wallops Island, Va. on Sunday, Sept. 9 at 7:17 a.m. EDT.
At 8 a.m. on Sept. 9 the center of Tropical Storm Humberto was located near latitude 13.4 north, longitude 23.3 west, just 92 nautical miles south of Praia, in the Cape Verde Islands. Humberto is moving toward the west near 12 mph/19 kph, and the storm is expected to turn to the west-northwest. Maximum sustained winds are near 40 mph/65 kph and is expected to briefly become a hurricane over the next day or two before weakening again.
The National Hurricane Center noted that the center of Humberto will pass south of the southern Cape Verde Islands this afternoon and tonight and pass west of the islands on Tuesday, Sept. 10.
Meanwhile, an elongated area of low pressure that include the remnants of tropical depression Gabrielle are still lingering in the western Atlantic. That broad area of low pressure is located about 500 miles south-southwest of Bermuda. Because of wind shear on Sept. 9, the shower and thunderstorm activity remains displaced to the east of the center as it was on Sunday, Sept. 8. Upper-level winds are not expected to be conducive for significant development while the low moves northeastward to north-northeastward during the next several days. This system has a low chance, 10 percent, of becoming a tropical cyclone during the next two days
Farther west, the National Hurricane Center noted that a low pressure area could form over the Bay of Campeche in the southwestern Gulf of Mexico in the next couple of days.
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