Update — July 3, 4:42 p.m. ET: Astronaut Gerst posted this image of the newly formed hurricane.
Update — 7:11 p.m. ET: Astronaut Reid Wiseman posted an image of storms over Maryland.
Update — 5:04 p.m. ET
Tropical Storm Arthur is almost a hurricane. The hurricane warning has been issued for the North Carolina coast with strong winds and flooding likely for both Carolinas until Friday.
Update — 2:06 p.m. ET
The NHC expects Arthur to pass well east of the northern Florida coast.
Update — 11:00 a.m. ET
The NHC has issued a tropical-storm warning for the North Carolina coast.