ECM “weeklies” reign number one predicting the 500 MB height pattern across North America for the week 2-4 outlook during the past 30 days.

A tropical disturbance in the east-central North Atlantic basin is developing. A tropical cyclone is likely by midweek. Upper shear northwest of this system may slow significant development. This system will stay well out to sea. Otherwise, no significant tropical cyclone risks exist in the 10-day outlook.

The remarkably dry weather pattern across the South and East U.S. shifts stronger in the overnight ECM ENS 15-day forecast. Patchy wet monsoon moisture is confined to the western half of the U.S. In the 16-30-day period, the best fit forecast is the AI Graph Cast ECM ENS which reveals increasing wet risk across the U.S. although the East remains mostly drier than normal.

Signaling additional cooling ahead in the Nino SSTA regions is the cool-off of the subsurface equatorial East Pacific. The subsurface cooling has accelerated during September. La Nina evolution will continue into Q4/2025.