During recent years, the (certain) catalyst to a category-4/category-5 major hurricane has been travel of the tropical cyclone across 31C/87F (or warmer) SST. Right now, the SST for the most likely path of Helene is 30C/86F certainly sufficient to fuel a category-3 major hurricane. The SST across the northeast Gulf of Mexico is a scary 0.75C to 1.75C warmer than normal. 

A tropical cyclone is forecast to generate in the western Caribbean Sea in a couple days and then turn northwest and north becoming a hurricane in the eastern Gulf of Mexico heading toward the Big Bend Area in northwest Florida. GFS, ECM, and AIFS are in reasonable agreement with landfall but vary widely with where the storm tracks once inland.

The Madden Julian oscillation (MJO) is forecast to shift eastward from Maritime Continent (of the past several weeks) across the tropical East Pacific to tropical Africa over the next 2-3 weeks. The eastward shift should activate the North Atlantic tropics and increase risk of a wider wet weather pattern for Brazil.

The weekly Crop Moisture Index valid for Sep. 8-14 reveals a wetter regime across the southeast quadrant of the U.S. while opposing critically dry conditions exist in the eastern Ohio Valley, much of the west and southwest Great Plains, and Southwest U.S.