coordinates are LCC parameters that select the [AWIPS 221][awips221]
and [AWIPS 226][awips226] projections respectively (`lat_1`
corresponds to `Latin1`, `lat_2` corresponds to `Latin2`, and `lon_0`
-corresponds to `Lov`).
+corresponds to `Lov`; see [this description][lcc-param] of the
+two-standard-parallel LCC and its PROJ.4 parameters).
Convert our lat/lng pairs into grid points:
[LCC]: http://en.wikipedia.org/wiki/Lambert_conformal_conic_projection
[awips221]: http://www.nco.ncep.noaa.gov/pmb/docs/on388/tableb.html#GRID221
[awips226]: http://www.nco.ncep.noaa.gov/pmb/docs/on388/tableb.html#GRID218
+[lcc-param]: http://www.remotesensing.org/geotiff/proj_list/lambert_conic_conformal_2sp.html
[UTM]: http://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_system
[zone]: http://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_system#UTM_zone
[geopy]: http://code.google.com/p/geopy/