Just Halfway Through May, And TS Arthur Organizing; Likely Glancing Blow On NC Outer Banks
tropical storm warning was in effect along the North Carolina coast as the first named storm of the Atlantic season, Arthur, slowly intensifies. As of 11 am EDT Sunday, a tropical storm warning is in effect from Surf City north to Duck, including the Pamlico and Albemarle sounds. Arthur was centered at 11 am EDT about 345 miles south-southwest of Cape Hatteras, NC, and moving north-northeast at about 9 mph. Top sustained winds in Arthur were 45 mph, according to the NOAA/NWS National Hurricane Center (NHC).
Arthur was a highly asymmetric storm on Saturday nightmore like a subtropical storm in some ways, with most of its strong showers and thunderstorms (convection) east of its center. On Sunday, Arthur appeared to be organizing more solidly in tropical-storm mode. Convection remained fragmented and still mostly on the north and east sides of Arthur, but the storms circulation was becoming more symmetric. With wind shear reduced from Saturday, the upper-level outflow had improved.
Outlook for Arthur
Upper-level wind shear will remain light (less than 10 knots) over Arthur through Sunday, giving the storm a window to organize and intensify. Sea surface temperatures of around 25-26°C (7779°F) are below the usual threshold of 26°C for tropical development, but Arthurs northward trek over the Gulf Stream will give it access to the warmest possible water, and cold air aloft will help compensate for the reduced instability from the less-than-toasty water. The mid-level air in the vicinity of Arthur will remain moderately moist (relative humidity of 5565%), although dry air intrusions from land may hinder Arthur's convection at times.
Southwesterly flow ahead of a deep trough in the central U.S. will continue to steer Arthur north-northeastward over the next day or so. This track will bring Arthur over or near the Outer Banks of North Carolina on Monday, with a brief landfall possible. By this point, NHC predicts that Arthur will be a 60-mph tropical storm. Impacts in the Outer Banks be limited by the angle of approach, which will minimize storm surge and keep Arthurs strongest winds mainly offshore. Squally tropical-storm-force winds and doses of heavy rain will be possible across and near the Outer Banks, mainly in the 1-2 range but up to 4 locally.
EDIT
https://www.wunderground.com/cat6/arthur-strengthens-en-route-to-north-carolina