GribStream Blog
NBM fix restores tropical 10 m wind grids when NHC data are missing
NWS updated NBM tropical wind processing so missing NHC 10 m wind grids are replaced with deterministic 10 m wind fields, starting Sept 2, 2025 at 13Z.
On September 3, 2025, NOAA/NWS announced a fix to the National Blend of Models (NBM) that addresses missing tropical 10 m wind grids. The change was implemented September 2, 2025 at 13Z.
What changed
When the National Hurricane Center (NHC) provided incomplete tropical 10 m wind speed and direction grids, some NBM outputs were missing values. The updated NBM process now replaces missing NHC grids with deterministic 10 m wind grids, preventing gaps in the tropical wind fields.
The change applies to:
- CONUS
- Hawaii
- Puerto Rico
- Oceanic
Why it matters
Missing wind grids can disrupt tropical hazard workflows, marine routing, and operational dashboards. The deterministic fallback ensures continuity when NHC grids are incomplete, improving stability for downstream products that depend on consistent 10 m wind fields.
What this means for GribStream users
GribStream already supports NBM. We will keep tropical wind fields aligned with NOAA's updated processing and incorporate any future NBM changes as soon as updated data are available via the AWS Open Data program.
Sources
- NWS Service Change Notice 25-69 (Sep 3, 2025): https://www.weather.gov/media/notification/pdf_2025/scn25-69_nbm_v4.3.8_0-day_gsm.pdf