alt Catalog http://mtarchive.geol.iastate.edu/thredds/catalog/mtarchive/2021/08/21/gempak/upperair/catalog.html

Dataset Size Last Modified
     Folder  upperair   --
         20210821_upa.gem 5.808 Mbytes 2021-08-22T01:47:01Z

ISU MTArchive at ISU MTArchive see Info
THREDDS Data Server [Version 4.6.14 - 2019-07-23T11:04:31-0600] Documentation