Tropical Storm Bertha has held on to Tropical Storm status since it’s upgrade early Thursday morning. I was curious about the early call but in the end as of now Bertha appears to be a legitimate tropical storm. Bertha had to survive quiet a violent environment that contained very dry air and wind shear. Now Bertha has to overcome one more barrier, the land mass of Puerto Rico and Hispaniola.
These countries have very mountainous topographies and could easily disrupt a small circulation like the one the currently resides in Bertha. There are two options that could occur, the first is Bertha remains intact after crossing the countries or second, Bertha becomes a tropical wave. Either option will ultimately not matter as an end result will be similar.
The northern Caribbean has very warm sea surface temperatures, much higher than the waters Bertha is currently in. By that time the dry air will not longer be a major factor as the upper-level trough that resides over the eastern CONUS will be transporting an abundance of moisture northward ahead of the storm. This combined with lower shear could allow Bertha to obtain category 1 hurricane status by early next week.
Bertha is still being steered west-northwest by the strong ridge over the central Atlantic Ocean. The upper-level trough over the eastern CONUS will break into the western side of the ridge. As it does so, Bertha will begin to make a turn to the northwest and eventually north then northeast as it rounds the western flank of the ridge. It will begin to gain some forward speed as it merges with the upper-level trough and will push it out to sea without making landfall on the CONUS.
Some increased confidence has been aided by the general consensus among the majority of the forecast models with respect to forecast track. Intensity is still varied although recent thinking is Bertha could reach category 1 hurricane strength over the next two or three days. Shortly after this, Bertha will begin to be absorbed with the upper-level trough and become post tropical by that time.
I will conclude with mentioning that at this time there does not appear to be any threat with land. The upper-level trough will serve to turn Bertha away from the CONUS before it arrives.