+Three- versus 24-hour ranges
+----------------------------
+
+By default, this program will fetch three hours of data from the
+provider. This way, if the most recent record has any missing data, it
+can examine the two hours prior, using whatever data it can find.
+
+There are two features which will cause the program to expand the time
+range of fetched data from three to 24 hours. Please be aware of this
+expansion as it may cause a rise in data/API usage.
+
+### Wind mode
+If you go to submit a Wx observation in InfoEx at e.g. 05:05, and have
+so configured InfoEx, it will take the wind speed, wind gust speed, and
+wind direction, from that hour and auto-fill it for the observation.
+
+Some operations may find it more important to know the averages for
+those values over the prior 24 hour period. Setting `wind_mode` to
+`average` will enable that.
+
+### HN24
+As most stations do not provide HN24 on their own, this program provides
+a configuration option for calculating this. Simply add `hn24 = true` to
+the configuration file.
+
+*NOTE: This is its own configuration option, rather than a new value for
+ desired_data, because it's not technically provided by MesoWest
+ or NRCS SNOTEL.*
+