Bertha back at Category 2 strength
Hurricane Bertha is back at Category 2 status, and appears destined to become one of the longest-lasting July hurricanes on record. Hurricane Emily of 2005 spent seven full days at hurricane strength in July, which I believe is the record. Bertha is halfway there. The storm is in no hurry to recurve out to sea, and will spend 3-4 more days over waters warm enough to maintain it at hurricane intensity. At that time, wind shear is expected to increase to 30 knots, which should knock Bertha down to tropical storm status. The models continue to show that Bertha may slow down and move erratically this weekend, and possibly threaten Bermuda. By the middle of next week, Bertha should be headed towards the Maritime Provinces of Canada, and may affect them as a tropical storm.
Figure 1. This natural-color image of Hurricane Bertha was captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite on July 9, 2008, at 14:45 UTC (10:45 a.m. Eastern Daylight Time). Shortly after, the National Hurricane Center estimated that Bertha was a Category 1 storm, with maximum sustained wind speeds of 75 miles per hour. Bertha was compact when MODIS observed it, a small ball of clouds with a long line of thunderstorms trailing away to the southeast. The eye of the storm had clouded over. Image credit: NASA.
Elsewhere in the tropics
There are no threat areas to discuss in the tropical Atlantic. The ECMWF model is predicting that a tropical depression may form between Africa and the Lesser Antilles Islands in seven days. The UKMET and GFS have shown a similar development during various runs over the past two days, but their current runs are showing just a strong tropical disturbance in this region next week. Stay tuned.
I'll post an update Friday morning.