The first tropical storm of the Atlantic hurricane season formed off the Florida coast last night, and the system is going to skim the east coast of the United States before heading out to sea next weekend. Even though the worst weather will affect mostly the Outer Banks, it could still have a dangerous impact on the beaches this holiday weekend.
The latest advisory from the National Hurricane Center has Arthur sitting off the Florida coast as a strengthening tropical storm. The system has 50 MPH winds as it just barely drifts towards the northwest. The storm will start to accelerate over the next day or two as a trough in the jet stream draws closer.
As of now, the forecast shows Arthur becoming a category 1 hurricane when it hits and runs parallel to the North Carolina coast on Thursday night and Friday morning. Then-Hurricane Arthur could have winds between 80 and 90 MPH as it hits the Outer Banks on July 4, which is a major problem for both officials and tourists, as the area is packed to the gills with beachgoers in the area for the long weekend.
Where will Arthur go?
As shown by the forecast track map above, they predict that the center of Tropical Storm Arthur will travel roughly parallel with the southeastern coast before quickly heading out into the northwestern Atlantic, eventually hitting Newfoundland as a subtropical storm.
The effects of tropical cyclones extend well beyond their centers of circulation, so do not focus on the center of the track. The white bubble that extends out from either side of the predicted path is called the cone of uncertainty.
The cone of uncertainty is the margin of error in the National Hurricane Center's predicted track forecast. Meteorologists take the error of their previous forecasts and use the average track errors to create the cone of uncertainty. Weather forecasting is an inexact science, and this is especially true for forecasting hurricanes. Arthur's center of circulation could wind up anywhere within the cone as it moves along the coast, and there's even an outside chance that it could wind up outside of the cone of uncertainty.
If Arthur's path tracks further to the west than predicted, it could pose serious problems for coastal areas from the south up through New England. If it tracks further east, it'll be less of a problem.
What are Arthur's impacts?
The storm will have relatively significant impact on the Carolina coast, but especially so for the Outer Banks where Arthur's center is expected to pass over or very near to. Here's a rundown of the effects residents and visitors can expect from Arthur later this week, provided the outcome stays true to the current forecast:
- High winds are a threat, especially if coastal areas see winds reaching hurricane force. Expect airborne debris and wind damage to trees, structures, and power lines in the areas that see the highest winds. The NHC regularly updates graphics showing the probability of seeing tropical storm and hurricane force winds.
- Heavy rains will occur over coastal areas and even slightly inland. Locations closer to the path of the storm could see between 2 and 4 inches of rain, with more possible in the heavier rainbands. This could lead to some flooding in low-lying areas.
- Rip currents are going to be a major hazard on beaches on the east coast this week as Arthur gathers strength and starts moving on up. More than 100 people die due to rip currents every year. A rip current is a strong current just beneath the surface of the water near land that pulls you out away from the shore. If you're ever caught in a rip current, swim parallel to the shore until you're out of the current.
- As with any storm, a storm surge is likely with Arthur, although it should be on the small side. Even a small storm surge can cause coastal flooding, especially when combined with high waves and the low-lying elevation of the Outer Banks.
Residents should start making preparations now for a hurricane on July 3 and July 4. If you're a visitor, listen to local authorities and if they tell you to leave, leave.
The National Hurricane Center will release its next update on Arthur at 8 PM, followed by a full forecast by 11 PM.
[Satellite image by GOES, track map by the author with data from the NHC]