Former Hurricane Lowell weakened to a tropical storm as it moved away from Kauai on Tuesday evening. At 11:00 a.m. EDT on Tuesday the center of Tropical Storm Lowell was located at latitude 26.2°N and longitude 161.1°W which put the center about 310 miles (500 km) north-northwest of Lihue, Hawaii. Lowell was moving toward the north at 18 m.p.h. (30 km/h). The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h). The minimum surface pressure was 978 mb.
Former Hurricane Lowell weakened to a tropical storm on Tuesday evening. A large upper level trough that was south of the Aleutian Islands was producing strong southerly winds that were blowing toward the top of Lowell’s circulation. Those winds were causing strong vertical wind shear.
The strong vertical wind shear was affecting the structure of Tropical Storm Lowell. Thunderstorms were still occurring in bands in the northern half of Lowell’s circulation. Bands in the southern half of Tropical Storm Lowell consisted primarily of showers and lower clouds. Storms near the center of Lowell generated upper level divergence that pumped mass away to the north of the tropical storm. The removal of mass in the upper levels was less than the convergence of mass in the lower levels of the atmosphere. So, the surface pressure increased on Tuesday.
The strong vertical wind shear also caused the distribution of wind speeds in Tropical Storm Lowell to become more asymmetrical. Winds to tropical storm force extended out 250 miles (400 km) in the northern side of Lowell’s circulation. Winds to tropical storm force extended out 160 miles (260 km) in the southern side of Tropical Storm Lowell.
Tropical Storm Lowell will move through an environment that will be unfavorable for intensification during the next 24 hours. Lowell will move over water where the Sea Surface Temperatures are near 26°C. However, the upper level trough that is south of the Aleutian Islands will continue to cause strong vertical wind shear. Tropical Storm Lowell will continue to weaken on Wednesday because of the strong vertical wind shear.
Tropical Storm Lowell will move south the southern side of a high pressure system that is over the North Pacific Ocean. The high pressure system will steer Lowell toward the west during the next 24 hours. On its anticipated track, Tropical Storm Lowell will move farther away from Hawaii.