Typhoon Florence is now expected to develop into a major hurricane as it nears the US East coast, with impacts including damaging winds, storm surge, heavy ocean swell, and rainfall.

Guidance from JLT Re suggests Florence will track toward the coast of the US by early Friday morning.

On its current trajectory, it appears the hurricane will track slightly north of the border between South Carolina and North Carolina border before making landfall as a major hurricane.

Both model guidance and the National Hurricane Center official forecast include a period of rapid intensification for Florence in the next two-to-three days.

Intensity across various models places Florence at between a Cat 3 and Cat 5 through the four-day forecast, immediately prior to a potential landfall.

JLT Re said a Cat 4 storm impacting the Carolina coast would be dangerous and impactful.

Although the NHC has not yet begun to issue official surge forecasts, the stretch of coastline is particularly vulnerable because of low lying barrier islands and inland waterways and bays that can amplify surge.  Surge could exceed 9 feet in areas.

An additional threat will be rainfall, particularly given the current forecast of Florence slowing and potentially stalling at the coastline.

The Caribbean, which was pounded in the third quarter of 2017 by Hurricane Maria, is currently under threat from Tropical Storm Isaac which is on track to hit the islands later this week.