Highlight: Trouble brewing for Gulf of Mexico and East U.S. to close September. Fiona easily roars to category-4 strength midweek.
Discussion: Operational models are steadily indicating tropical cyclone development in the Caribbean Sea to the Yucatan Peninsula region next week. The likely path of travel is northwest or north through the eastern half of the Gulf of Mexico and across sufficiently warm water to generate a major hurricane. The most likely coastal target is the northeast Gulf of Mexico. The seasonal forecasts have been cut-back BUT it only takes one storm to create havoc and the tendency for very strong storms due to the anomalous warm ocean is why identifying this potential risk which is 9-10 days away is required now. The most recent GFS forecast (Fig. 1) indicates a storm maintaining strength well inland to unload heavy rain and high wind throughout the East U.S. after a Florida landfall. Close monitoring is required…the trend since yesterday is storm potential for the eastern half of the Gulf rather than the western half.
Meanwhile, as stated yesterday, Fiona is an over-achiever. Crossing the Puerto Rico/Dominican Republic high terrain while still strengthening yesterday said a lot about the potential energy Fiona contains. Now that the storm is away from land and forecast to move over 85F water forecast models take minimum surface pressure to the 930’s MB range southwest of Bermuda when a category-4 major hurricane is present and then once north of 40N surface pressure could drop below 930 MB causing a strong category-4 major hurricane at a high latitude. Fiona will become an immense storm affecting much of the western North Atlantic either directly due to extreme wind and rain or at a distance with high waves battering the East Coast with tropical storm force wind gusts at the coast especially New England.
At 8AM EDT Category-3 Major Hurricane Fiona is located about 10 miles northwest of Grand Turk Island with maximum wind at 115 mph and surface pressure 960 MB. Movement is north-northwest at 10 mph. Tropical cyclone models indicate Fiona will turn northward tomorrow night and northeastward Thursday/Friday and eventually northward again into Southeast Canada Saturday (Fig. 2). Tropical cyclone model intensity forecasts are too shy about category-4 intensity which is guaranteed given rate of strengthening of Fiona (Fig. 3).
The area of convection in the central North Atlantic deep tropics may be the beginning of the system that threatens the Gulf of Mexico later next week (Fig. 4).
Fig. 1: Operational models are steadily indicating a major hurricane risk in the Gulf of Mexico later next week. The latest GFS takes that storm inland Florida and through the East U.S. States unloading extreme rainfall.
Fig. 2-3: Tropical cyclone model forecast tracks and intensities for Category-3 Major Hurricane Fiona.
Fig. 4: North Atlantic basin weather satellite view.