Tropical Storm Bertha is continuing to race westward and slowly strengthen. As of the 11 pm advisory, Bertha’s maximum sustained winds were at 55 knots, just below the 64 knot threshold for hurricane strength. The satellite appearance has improved markedly with a burst of strong central convection.
A key to understanding Bertha’s intensity is the warmth or amount of fuel available in the ocean surface layer. The “heat content” map shows the track of Bertha towards a more favorable environment for intensification. However, it is still July, and there is a definite cap on maximum intensity possible, which would be at just under 100 knots or Category 3 strength. This would require perfect atmospheric conditions including very low shear but high relative humidity or “juice”. The likelihood of a US landfall is very low at this point in time, but not zero.