NOAA Radar and Satellite Fetching

NOAA Radar and Satellite Fetching defines a retrieval workflow that preserves product, platform, spatial sector, and scan-time identity. It covers NEXRAD archive volumes, real-time chunks, selected Level III products, and GOES products such as ABI or GLM. It does not fetch numerical model output or ordinary station observations.

A radar request identifies the product level, four-character site, desired UTC scan time, direction policy, tolerance, volume or product code, retention policy, and decoder. A satellite request identifies the physical satellite or operational role, instrument, product, sector, channel, time tolerance, and required calibration form. East and West roles are resolved against current NOAA documentation because a role is not a permanent satellite number.

Discovery uses the smallest date/site or product/year/day/hour prefix that can contain the requested scan. Adjacent periods are included only when tolerance crosses a boundary, and pagination and inspected keys remain bounded. Unsigned public archive access uses placeholders that must be validated and replaced:

aws s3 ls --no-sign-request \
  s3://unidata-nexrad-level2/YYYY/MM/DD/KXXX/

Selection uses measurement time instead of object Last-Modified. NEXRAD filenames provide a candidate site and scan timestamp, confirmed later from the decoded header. GOES filenames encode scan start, scan end, and creation time; scan start or interval overlap drives selection. Retrospective requests default to the closest scan at or before the requested instant. Future scans require an explicit nearest-in-either-direction policy, and every candidate must satisfy the tolerance and requested sector.

Use the skill when a task requires a completed radar volume, selected radar product, or satellite object for a time and region, including uncertain bucket routes or satellite assignments. Ordinary historical processing favors archive volumes. Real-time chunks are appropriate only for consumers that assemble and validate them. Merely displaying a third-party tile or answering a general weather question does not require this workflow.

The skill does not guarantee meteorological suitability, perform mosaicking, implement scientific calibration, or repair historical gaps and outages through fallback. Product levels, sectors, scan modes, and platforms must not be blended without recording the transformation.

Before transfer, record bucket, exact key, size, ETag, and publication metadata. Download into a request-owned temporary location, verify byte count and an available provider checksum or local SHA-256, and open with an installed format-aware reader. Internal site or platform, product, scan interval, dimensions, and radar sweeps must match before caching.

Radar checks preserve sweep details, moments, elevation angles, missing gates, quality masks, range folding, and velocity ambiguity. Satellite checks verify instrument, sector, channel, scan mode, geostationary projection, scale and offset, fill values, and quality flags. Fixed-grid coordinates are not relabeled as latitude and longitude.

Public S3 access uses unsigned requests while retaining TLS verification. Current routes come from the AWS Registry of Open Data. Cache identity combines bucket, key, and object identity. Bounded retries and resource limits keep partial downloads separate; cleanup removes only request-owned raw files after the final artifact and provenance manifest are durable.
If publication is still in progress, require stable metadata or a conditional request pinned to the observed identity. Validate site, product, channel, sector and time before constructing paths. Keep credentials, private endpoints and subscription tokens out of records; preserve NOAA attribution without implying endorsement. Cleanup never deletes a shared user cache.

Do not reuse the retired noaa-nexrad-level2 route. Resolve archive, chunk, Level III and satellite-specific buckets through the current AWS Registry of Open Data. Radar availability at a location depends on distance, beam height, terrain blockage and outages, beyond nominal coverage radius. Continuous real-time ingestion can use event notifications instead of repeatedly scanning broad prefixes.