The U.S. National Hurricane Center says Ophelia is expected to become a hurricane by Wednesday.
Wind shear - which could disrupt the storm's development - is light, and it is passing over sea surface temperatures much warmer than normal, which should help it sustain hurricane strength through at least Friday.
Ophelia developed into a tropical storm less than 48 hours after Hurricane Nate made landfall on the northern Gulf Coast of the United States. This has not happened in 124 years, or since 1893.
Ophelia could brush by the Azores this weekend.
Ophelia would become only the third tropical cyclone to hit the west coast of Portugal or Spain since records began, following a storm in October 1842 and Hurricane Vince (as a tropical depression) in October 2005.
Center officials said the hurricane is forecast to drift northeastward over the next 24 hours.
Moses later tweeted that if separated, there would be a tropical storm, then a separate hurricane, which would make the 10-straight-hurricane record invalid.
Ireland regularly deals with the remnants of tropical systems, but Ophelia is going to approach the island as a stronger system than the usual remnant lows. It is now forecast to stay west of Portugal before bringing gusty winds and rain to Ireland early next week. On Wednesday afternoon, hurricane-force winds from Ophelia extended outward up to 25 miles from its center.
Only 15 hurricanes have passed within 200 nautical miles of the Azores since 1851, according to NOAA's historical hurricane database.