A cluster of thunderstorms to the east of Florida has now developed into the first Hurricane of the Atlantic Hurricane Season.
The system was upgraded to a Tropical Storm at 15GMT on Tuesday, and named Arthur. Although other storms have formed to the west of Mexico, this is the first one this year to form in the Atlantic.
Tropical Storm Arthur is currently moving at just 13kph and is quickly becoming more organised. Favourable conditions mean that it is expected to strengthen over the next 24 hours.
Warm sea waters are the energy source of a tropical system. Great amounts of energy are transferred when warm water is evaporated from tropical seas. As humid air rises, energy is released when the water vapour condenses, producing the towering cumulus clouds and rain seen within a tropical storm.
The waters to the east of the USA are currently 1C above average, and this will give extra energy to the system and allow Arthur to strengthen.
The winds will also help the system become stronger. They are fairly similar throughout the atmosphere, something meteorologists call low 'wind sheer'. This will ensure that the system isn't disrupted as it grows vertically throughout the atmosphere.
It has already produced heavy rain in Florida, with Miami reporting 98mm of rain on Sunday and Monday, and Freeport in the Bahamas reporting 149mm in just 24 hours.
The system is expected to strengthen further, as it runs up the east coast of the USA. It is forecast to graze the coast of North Carolina, reaching its closest point or perhaps even crossing the coastline around 6GMT on Friday.
This will bring severe weather to the region. Warnings are in force for winds in excess of 119kph, a storm surge which could reach 1.3metres, up to 150mm of rain and dangerous rip currents.
This is an unfortunate time for the storm to affect the east coast, as this weekend is a holiday weekend in the US. Many of the hotels in the region are fully booked for the Independence Day celebrations, known as Fourth of July.
Officials in North Carolina's Outer Banks said they had closed Cape Lookout National Seashore on Wednesday evening and would only reopen when it's safe.