Arthur (2020)

A low-pressure area that formed over the Florida Straits mid-May organized into a tropical depression on May 16, 2020 about 110 nautical miles east of Melbourne, Florida, and became Tropical Storm Arthur early on May 17 about 165 nmi east-northeast of Cape Canaveral. Arthur moved north-northeast along the U.S. East Coast, passed east of central Florida and near the Georgia and South Carolina coasts, then tracked close to the Outer Banks of North Carolina on May 18–19. The system began interacting with a frontal boundary and became an extratropical cyclone by 1200 UTC May 19 while about 350 nmi east-northeast of Cape Hatteras, then produced gale-force winds near Bermuda before dissipating early on May 21.

Arthur did not make a U.S. mainland landfall as a tropical cyclone; its center passed about 20 nmi east-southeast of Cape Hatteras, North Carolina on May 18 while still tropical. Tropical Storm Watches were issued for parts of the North Carolina coast on May 16 and upgraded to Tropical Storm Warnings on May 17; those warnings were discontinued by the evening of May 18–19 as the center moved offshore and weakened.

The storm’s peak intensity as a tropical cyclone was 50 knots (about 58 mph) with a minimum central pressure near 990 mb (the best-track minimum pressure listed at 990 mb at 0600 UTC May 19). Satellite scatterometer data and aircraft overpasses supported the 50‑kt peak; winds briefly reached 55 kt after the cyclone became extratropical as the wind field expanded.

Storm surge along parts of the mid-Atlantic and southeastern U.S. was minor. The highest water level relative to Mean Higher High Water was 1.47 ft at the Chesapeake Channel opening to Chesapeake Bay, Virginia, and in North Carolina the peak water level recorded was 1.19 ft at Duck. Overwash and standing water closed at least one highway on the Outer Banks and another on the mainland. Rainfall totals were heavier in southeast Florida and the Keys before genesis — Marathon reported a daily record of 5.76 inches on May 14 and up to 9.95 inches in parts of the island — and along eastern North Carolina Arthur produced 3–5 inches across Carteret, Craven, Pamlico, and Onslow Counties, with a high of 5.01 inches at a station in Croatan, Craven County.

There were no known fatalities directly attributed to Arthur. The precursor disturbance and onshore flow produced dangerous rip currents: Volusia County, Florida reported about 70 water rescues on May 17 and three people were hospitalized. Minor damage occurred on Grand Bahama Island to tents and temporary shelters used for Hurricane Dorian relief. No significant structural damage was reported in North Carolina.

Noteworthy points: Arthur formed before the official June 1 start of the hurricane season, marking the sixth consecutive year with a pre-season named storm. The National Hurricane Center’s watches, track, and intensity forecasts verified well; official track and intensity errors were below recent 5‑year means, and genesis was anticipated in Special Tropical Weather Outlooks issued up to about 100 hours in advance.