I've cracked the system for efficiently using NOMADS data. I'm using an R package rNOMADS. It's a system where you can quiz and selectively download a large set of gridded data. It gives me access to many new resources for high frequency data, including reanalysis.
Anyway, as a first experiment, I downloaded GFS 0.5° surface relative humidity data ("gfs_0p50","rh2m"). This data is prepared for the forecast system, and held for about 12 days. So here we have a movie of the data from 11th to 23rd November, at 6 hour intervals. This is all experimental; the movie is ogg, so should show on Firefox and Chrome, but probably not on IE or Safari. Update - I've made an alternative mp4 version, which works in Safari at least. It has the usual controls - you may need to pass the mouse pointer below the picture to make them show. Blue is high humidity, red dry. A color key will appear at some stage.
What NPR Misses About Energy Jobs In America
1 hour ago