The IEM attempts to process all SHEF encoded products that come via a NOAAPort data stream. The identifiers used by the stations reported in this data feed are supposed to adhere to the SHEF Manual specification for site identifiers. The most common set of identifiers are found within the National Weather Service Location Identifier (NWSLI) database. Unfortunately, not all site ids used by issuance centers are contained within NWSLI. This page lists out unknown NWSLI-like identifiers.

The IEM gets about a quarterly dump of the NWSLI database, which was most recently received on 2025-05-21. So newly added sites to NWSLI and listed here would be false positives. The IEM maintains only a seven day archive of raw SHEF products, so thus why only some links are active within the table.

This page is similar to NOHRSC's Unknown Stations, but this page only contains NWSLI-like identifiers.