The immediate forecast issues include risk of another Gulf of Mexico tropical cyclone. NOAA/NHC identifies a tropical wave southwest of Jamaica having a 50% chance of tropical cyclone development after 48 hours. The 12Z GFS indicates the system develops slowly and eventually reaches the north/northeast Gulf of Mexico Coast early in the 6-10-day period.

The U.S. week 2-4 outlook features sprawling high pressure across the West and Central U.S. producing a nationally drier and warmer than normal climate through mid-autumn. The Gulf of Mexico may be tropically active (after Helene) otherwise rainfall in the U.S. is sparse.

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.