GribStream Blog
GEFS aerosol 06/18Z cycle discontinuation proposed for 2026
NWS proposes ending the 06Z/18Z GEFS aerosol component forecasts by April 1, 2026, while keeping the 00Z/12Z aerosol cycles and all non-aerosol GEFS members unchanged.
On July 25, 2025, NOAA/NWS proposed discontinuing the GEFS aerosol component forecasts initialized at 06Z and 18Z, with a proposed termination date on or before April 1, 2026. Public comments were requested through August 24, 2025.
What is changing
- The aerosol component (dust, sea salt, smoke) would run only at 00Z and 12Z instead of all four cycles.
- No changes are proposed for the 00Z/12Z aerosol cycles.
- No changes are proposed for the 06Z/18Z non-aerosol GEFS ensemble or control member forecasts.
Why it matters
If you rely on aerosol fields for air-quality analyses, wildfire smoke, or dust forecasting, this reduces update frequency from four to two cycles per day. That can affect alert timing, model blending, and verification schedules.
What this means for GribStream users
GribStream supports GEFS Atmosphere with the full 31-member ensemble on a 0.25 deg grid. If NOAA implements this aerosol change and updated feeds are published through the AWS Open Data program, we will align our ingestion and document the cycle-level differences clearly.
Sources
- NWS Public Information Statement 25-52 (Jul 25, 2025): https://www.weather.gov/media/notification/pdf_2025/pns25-52_soliciting_comments_gefs_aerosol_termination.pdf