So I know we are supposed to buy a Kestrel, but one could just correct the weather data from the nearest source which are available on certain radios, or other sources such as the internet. It seems to be very difficult to find out exactly what changes are made to "un-corrected" or as (Kestrel calls it "station pressure") readings. I've seen 4 formulas that look quite different to me, but I did find a chart which I wonder if it is correct: http://novalynx.com/manuals/bp-elevation-correction-tables.pdf
The tricky part is that I don't know if temperature is taken into account when the correction is made by weather stations. Altitude certainly is.
There are a number of conversion websites but they go in the wrong direction from actual to corrected, and they don't really state what the weather people actually use.