Hurricane models (HWRF and HMON) initialize the 8AM EDT central pressure at 952-953 MB, so slightly too strong. HWRF takes Helene to a 935 MB/138 mph category-4 major hurricane by 8PM this evening with landfall across the Apalachee Bay area late this evening. HMON is not quite as strong, indicating 941 MB/133 mph category-4 major hurricane at 8PM this evening with landfall shortly after midnight in the Apalachee Bay area.

The southern oscillation index was neutral much of the past 1-2 weeks correlated to easing trade winds. However, +SOI is forecast to re-emerge. The subsurface waters in the equatorial East Pacific have cooled significantly the past 30 days indicating increased energy to fuel La Nina if trade winds become established.

Potential Tropical Cyclone Nine strengthens to a tropical storm by tonight and becomes a hurricane once reaching the southeast Gulf late tomorrow. The HWRF model takes Helene to a strong category-4 major hurricane in the northeast Gulf of Mexico on Thursday just prior to landfall.

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.