Bertha Develops East of the Lesser Antilles

Some interesting news came across my Twitter feed late last night. With Invest 93L going in and out of consciousness as it was being attacked by some dry air and shear, I wasn’t expecting the disturbance to be named by the National Hurricane Center.

On Thursday, recon found 40-knot winds with a well-developed center of circulation. The sudden jump in convection in the north and east side of the storm prompted the upgrade of the system.

Infrared satellite image from Friday morning (8:15 AM EDT) of Tropical Storm Bertha. (Source: NOAA)
Infrared satellite image from Friday morning (8:15 AM EDT) of Tropical Storm Bertha. (Source: NOAA)

 

This morning, Bertha is 110 miles east-northeast of Barbados and moving west-northwest at a brisk 20 mph.  This movement is expected for the next day or so. Maximum sustained winds are at 45 mph with a minimum central pressure of 1008 mb.

The tropical storm is expected to move over the islands tonight and move more northwest towards Puerto Rico sometime Saturday. Tropical storm warnings are already in effect for that island. Afterwards, guidance models are mainly keeping Bertha over the eastern Bahamas and moving more north.

A upper trough is expected to deepen across the eastern United States (see below) with a high off to the east over the Atlantic. These features are expected to help steer Bertha to the north and away from the eastern seaboard.

The 300-mb guidance run (GFS run for 8 AM EDT Monday) shows the trough that's expected to help keep Bertha offshore. (Source: WeatherBell)
The 300-mb guidance run (GFS run for 8 AM EDT Monday) shows the trough that’s expected to help keep Bertha offshore. (Source: WeatherBell)

Too much strengthening isn’t expected as Bertha could run into a little more shear and dry air ahead of it. Also, any interaction with the mountainous terrain of the Caribbean islands could also inhibit further intensification. The NHC keeps this as a tropical storm through the forecast period.

I’ll always keep an eye on it. I’ll let you know if things change, but it looks like a low risk of a direct impact to the U.S. at the moment.