Early on July 1, a strong and large tropical wave emerged off the coast of Africa. By early the next day, a surface low developed and the wave became better organized. The National Hurricane Center upgraded the system to Tropical Depression Two in the morning hours of July 3 after the system was able to maintain convection over its center for at least 12 hours. The depression organized further and developed two distinct bands of convection. Six hours after becoming a depression, it was upgraded to Tropical Storm Bertha, the second named storm of the season.The National Hurricane Center noted that this tropical cyclone was remarkably forecast up to a week in advance by many global computer models.

Arthur is the first reported tropical storm to form in May since Tropical Storm Arlene in 1981. Other systems have formed, but were subtropical (such as Andrea in 2007). Given Arthur’s very short lifespan, Jeff Masters questions whether it would have been reported and named in the years prior to today’s technology.The formation of Arthur also marks the first time that a named storm formed in May for two consecutive years