GribStream Blog
LAMP/GLMP v2.7 upgrade adds new flight-category guidance and visibility updates
NWS announced LAMP/GLMP v2.7 effective Sep 16, 2025, adding new flight-category bulletins, updated visibility thresholds, new station guidance, and an Alaska ceiling fix, with an Oct 9 update.
On August 12, 2025, NOAA/NWS issued Service Change Notice 25-62 for the LAMP/GLMP v2.7 upgrade, scheduled September 16, 2025 beginning with the 1400 UTC cycle. The upgrade targets aviation guidance and improves downstream inputs to the National Blend of Models (NBM).
Why it matters
LAMP and GLMP provide short-range aviation guidance for ceiling, visibility, wind, and flight categories. Because NBM ingests this guidance, changes in LAMP/GLMP can affect NBM visibility and flight-category products.
Key changes in v2.7
- New flight-category guidance for ceiling/visibility start and end times, with probabilistic information, delivered in three bulletin formats:
- Expanded sub-hourly (15-minute) bulletins out to 6 hours.
- Hourly extended flight-category bulletins out to 38 hours.
- Simplified bulletins listing UTC start/end times for each category.
- Updated station visibility thresholds to reduce over-forecast bias using station-grouped thresholds (initially implemented in v2.7).
- Ceiling/visibility guidance added for 335 stations in LAV/LEV text bulletins and BUFR.
- Alaska GLMP ceiling fix: ceilings above 12,000 feet are set to -100 in GRIB2 output.
- NOMADS filename changes for some LAMP/GLMP files; no changes to WMO headers or SBN routing.
October 9, 2025 update
NWS issued an updated notice reverting the station visibility thresholds change because it introduced inconsistencies in GLMP visibility at grid points that coincide with LAMP stations and impacted the NBM. The update also restores LAMP wind gust guidance at KJPX, KBCR, and KGDA, effective with the 1500 UTC cycle on October 9, 2025.
What this means for GribStream users
GribStream already supports NBM. These LAMP/GLMP changes directly influence NBM visibility guidance, so we track these upgrades closely. If LAMP/GLMP feeds become available via the AWS Open Data program, we will add them and document the changes clearly.
Sources
- NWS Service Change Notice 25-62 (Aug 12, 2025): https://www.weather.gov/media/notification/pdf_2025/scn25-62_lampglmp_v2.7.pdf
- NWS Service Change Notice 25-62 Updated (Oct 9, 2025): https://www.weather.gov/media/notification/pdf_2025/scn25-62_lampglmp_v2.7aaa.pdf