Over the weekend a cluster of thunderstorms moved into the Atlantic Ocean off the South Carolina coast and settled over the warm water of the Gulf Stream. Although the low is poorly organized and there is not much thunderstorm activity associated with it, conditions appear favorable for a tropical depression or storm to develop later this week.
Most of our reliable computer models increase the moisture and thunderstorm activity around the low during the day on Wednesday. They also move the system very slowly northward, which will help organize the thunderstorms around the low.
By late Wednesday we suspect a Tropical Depression will have formed offshore of Jacksonville, Florida. The system should further intensify Thursday while moving parallel the coast of Georgia and South Carolina.
By July 4, the depression will likely have reached Tropical Storm strength. If it does, it would be named Arthur.
Most models keep the center out to sea just off the North Carolina coast, however until we get better development of the system there is uncertainty and the low could move a little west and make landfall in eastern North Carolina.
After July 4, the storm should turn northeast away from land and move faster while merging with a cold front.
It is not unusual for early season storms to form off the southeast U.S. coast. We see no impact on our weather from this first system in the tropical Atlantic.