To support aviation and meteorology research needs, the IEM attempts to curate an archive of National Weather Service (NWS) Terminal Aerodome Forecasts (TAF)s. TAFs are text products that look a lot like METARs, for example a current TAF for Des Moines, IA (KDSM):

FTUS43 KDMX 221343 AAA
TAFDSM
TAF AMD
KDSM 221343Z 2214/2312 28011KT P6SM BKN120
     FM221500 27013G21KT P6SM BKN120
     FM222200 27008KT P6SM FEW120
     FM230300 15005KT P6SM FEW250=

A user of the available downloadable archive found that the IEM archive had a massive hole between 1 Jan 2010 and 4 Apr 2015 for all TAF sites. It is unclear what happened(^TM), but the raw text archive of this product was missing as well from the IEM NWS Text Product Archives.

So this hole was repaired by back-filling the raw text from the NCEI SRRS and reprocessing those historical TAFs into the archive database.

As always, please let me know when you find variances like these within the IEM archives.