Hurricane Earl has strengthened into a Category 4 storm, with maximum winds of 135 mph (215 kph), according to the latest update from the National Hurricane Center (NHC).
Earl is currently situated to the northeast of Puerto Rico and is expected to move to the northwest and along the East Coast of the United States over the next few days.
The storm, which was a Category 3 storm earlier on Monday, could intensify further over the next day or two. Earl is expected to be a major hurricane (Category 3 or higher on the Saffir-Simpson scale of hurricane strength) through Thursday as it skirts to the east of the Bahamas and other Caribbean islands.
Hurricane hunters flew through Earl on Sunday and Monday in an effort to better understand how these forces of nature form and intensify.
The NHC currently has tropical storm warnings out for Puerto Rico, the U.S. Virgin Islands, the British Virgin Islands, and Turks and Caicos Islands. The islands sit far enough west of the storm that they won't catch the brunt of the hurricane's ferocious winds.
Meanwhile, Hurricane Danielle is transitioning to an extra-tropical storm in the northern Atlantic and may impact southern Greenland. The storm's maximum sustained winds are around 70 mph (110 kph).
Danielle started causing problems for U.S. East Coast residents this weekend with large waves and dangerous surf conditions. News reports indicated that more than 100 people were rescued from dangerous currents in beaches from Maryland to New Jersey over the weekend. Waves near 10 feet (3 meters) however are expected to develop this afternoon along parts of Newfoundland, Canada as Danielle tracks northward.
Earl and Danielle have been joined by Tropical Storm Fiona, which formed from a tropical depression to the east of the Leeward Islands on Monday. Fiona has maximum winds of 40 mph (65 kph). Fiona is predicted to follow roughly in Earl's path, tracking to the east of many Caribbean islands.