Tropical Cyclone Dorian become a hurricane on 28 August 2019. By the early morning of the 29th, the Dorian remained a category 1 hurricane as it advanced to the northwest, north of Puerto Rico.

GOES-East IR imagery and Sea Surface Temperature derived product with NHC forecast track overlay show the hurricane expected to continue through very warm waters as it approaches the Florida East Coast (Fig 1). Temperatures are between 29C and 30C along the track, or around 85F.

A 1-min mesoscale sector from GOES-East was available over the system. The high resolution imagery aids forecasters in identifying the center of circulation, as well as in tracking thunderstorm activity. Visible imagery with a semi-transparent GLM Flash Extent Density overlay at sunrise on the 29th clearly showed the center of circulation, with areas of thunderstorms, some strong, embedded in the outer bands (Fig 2).

Zoom in view on center of circulation at sunrise Fig 3).

The strong thunderstorm just northeast of the center of circulation exhibited high flash rates (see Fig 2) as well as persistent overshooting tops and even an above anvil cirrus plume, much like we see with strong thunderstorms over the CONUS (Fig 4).

Bill Line, NWS