Subtropical Storm Don Develops West of the Azores

Subtropical Storm Don developed west of the Azores on Friday morning. At 5:00 a.m. EDT on Friday the center of Subtropical Storm Don was located at latitude 32.9°N and longitude 46.8°W which put it about 1165 miles (1875 km) west-southwest of the Azores. Don was moving toward the north at 6 m.p.h. (10 km/h). The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h). The minimum surface pressure was 1005 mb.

A large low pressure system over the central Atlantic Ocean west of the Azores exhibited more organization on Friday morning and the U.S. National Hurricane Center designated the system as Subtropical Storm Don. A distinct low level center of circulation was evident on visible satellite images. However, Subtropical storm Don was under an upper level trough. The bands near the center of Don consisted primarily of showers and lower clouds. Thunderstorms were occurring in a band that curled around the eastern and northern part of Don’s circulation. The strongest winds were occurring in that band of storms. Winds to tropical storm force extended out 200 miles (320 km) in the eastern side of Subtropical Storm Don. Winds in the western side of Don were blowing at less than tropical storm force.

Subtropical Storm Don will move through an environment only marginally favorable for intensification during the next 24 hours. Don will move over water where the Sea Surface Temperatures are near 26˚C. The upper level trough contains colder air, which will contribute to a more unstable atmosphere. However, the upper level trough will also limit the upper level divergence. There will be little vertical wind shear near the center of the upper level trough. Southerly in the eastern side of the trough will blow over the eastern side of Subtropical Storm Don. Those winds will cause more vertical wind shear in that area. The upper level trough could also circulate sinking, drier air around the western and southern sides of Don’s circulation. Subtropical Storm Don could maintain an equilibrium with its environment during the next 24 hours and its intensity may not change much.

The upper level trough will steer Subtropical Storm Don slowly toward the north during the next 24 hours. A high pressure system south of Greenland will block Don and prevent it from moving north on Sunday. Don is likely to move toward the east early next week. On its anticipated track, Subtropical Storm Don will meander west of the Azores during the next few days.