Isaias made landfall Monday night shortly after 11pm EDT in southern North Carolina near Ocean Isle Beach as a Category One Hurricane with maximum sustained winds of 85mph. According to the National Hurricane Center, data buoy near the coast of North Carolina reported a minimum pressure of 988 mb (29.18 inches) as it neared the coastline Monday evening.
Isaias weakened a bit, but remains a powerful Tropical Storm as it quickly moves up the East Coast, now moving through the New England states. Moving to the north/northeast around 40mph, Tropical Storm Isaias continues with sustained winds of 50mph. A gradual decrease in momentum and wind speed is expected as moves further north, closer to Maine within the next 12 hours before weakening even further as it moves into Canada.
Numerous reports of flooding, storm surge, wind damage and even tornadoes occurred along the East Coast, with the risk for isolated tornadoes in New England Tuesday evening. While flooding, high wind and storm surge are all expected with tropical systems, tornadoes can also occur. There were numerous reports of tornadoes from North Carolina all the way up to New Jersey and Delaware yesterday and today. Tornadoes associated with hurricanes and tropical storms often times occur in the thunderstorms within the embedded rain bands that spiral around the center of the hurricane, although they can also form near the eyewall (closer to the center). Most of the tornadoes that occur with tropical systems occur in the right, front quadrant of the storm – the part of the storm that moves from open water onto land. In this area, the instability and wind shear tend to the be the highest.
When the storm is over open water, there is very little (if any) friction to the slow the winds of the storm down. But once that storm begins to move onshore, friction increases as the air moves over land. This friction works to slow down the momentum of the wind near the surface, helping to enhance the wind shear within the rain bands or thunderstorms rotating around the center of the storm. Typically tornadoes that are produced by tropical cyclones are weak and short-lived, but there have been some tornadoes that have been significant – EF 2, or greater.