Current PSD (Web/Data Status). PSD has undergone major URL restructuring so that all URLs start with http://www.esrl.noaa.gov/psd/ (More Info).
PSD Datasets and Web Applications Status
Datasets Back Up A majority of PSD's gridded datasets, its web applications that use those datasets and some other datasets are now available. This also means FTP. Also TDS (OPeNDAP) is not available. We are working on a fix.
Not all datasets are affected (profiler and satellite are working). The www.cdc.noaa.gov and www.etl.noaa.gov URLs have moved. See the PSD web switchover page for more details.