NOAA CDAS to CORe in March 2026: what GribStream users should expect

NOAA is retiring CDAS and replacing it with CORe (Conventional Observation Reanalysis). The original notice, SCN 26-12, was published on February 9, 2026. NOAA later updated the implementation target to March 18, 2026. The PDF linked below is still the original February 9 notice, so it shows the earlier March 9, 2026 date.

For GribStream users, the important part is simple: this is not a file-format problem. CORe is still being published as public GRIB2. The real question is where NOAA publishes the replacement archive, because GribStream's current cdas ingestion is built around AWS-hosted archives.

CORe is still public GRIB2

NOAA's current documentation points to two public CORe paths. The first is the NOMADS operational tree, where recent data live under paths like https://nomads.ncep.noaa.gov/pub/data/nccf/com/core/. The second is NOAA's public cloud archive on Google Cloud Storage, documented under the bucket noaa-nws-ncep-core.

So this does not look like a case where the replacement dataset disappears from public access. It looks more like a distribution change: same general class of data, same GRIB2 family, different archive path and possibly a different product layout.

What GribStream expects

Our working assumption is that CORe will also show up in AWS. When NOAA rolls out a public operational GRIB dataset like this, an AWS-accessible mirror often follows. If that happens here, CORe should make its way into GribStream quickly.

That is the cleanest outcome and the one we expect.

What we cannot say yet is that the AWS path already exists. We have not verified one from NOAA's current documentation. So the question today is not "will CORe exist?" It is "when does the AWS mirror show up?"

If AWS is late

GribStream does not yet ingest from Google Cloud directly. Today our cdas path is built around AWS-hosted archives and the existing cdas.YYYYMMDD/cdas1...grib2 layout. So if NOAA leaves CORe available only through NOMADS and Google Cloud for a while, we would need to add that ingestion path on our side.

That work is already on the roadmap. It is more work than wiring up a new AWS prefix, but it is a solvable problem, and CORe is exactly the sort of dataset that makes direct Google Cloud ingest worthwhile.

Bottom line

If you use CDAS on GribStream, do not read this as "the data are going away." Read it as "NOAA is replacing the feed, and the archive path matters."

Best case, NOAA publishes a stable AWS mirror and CORe gets onboarded quickly. Slower case, we take the Google Cloud route instead. Either way, this looks more like an ingestion-transition problem than a dead end for the dataset itself.

We will keep watching the cutover, the archive paths, and the final product layout. If NOAA publishes a clean AWS mirror, expect CORe to move up the queue very quickly. If not, Google Cloud ingest is already on the roadmap.

Links

• CDAS model page
• CFS PGBF model page
• CFS FLXF model page
• Documentation

Sources

• NWS SCN 26-12 (Feb 9, 2026): https://www.weather.gov/media/notification/pdf_2026/scn26-12_CDAS_CORe_upgrade.pdf
• CPC CORe archive page: https://www.cpc.ncep.noaa.gov/products/CORe/archive.html
• CORe archive access notes (get_core.txt): https://ftp.cpc.ncep.noaa.gov/CORe/get_core/get_core.txt
• NOMADS overview and access page: https://nomads.ncep.noaa.gov/
• NOMADS CORe test/para directory: https://nomads.ncep.noaa.gov/pub/data/nccf/com/core/para/