C5 X means ceiling 500 feet with sky obscured. The letter C always identifies a forecast ceiling layer. Cloud heights are always referenced to ground level. Sky cover designators and height coding are identical to those used in the surface observation reports. Total sky cover at each level from a ground observers point of view is determined instead of the individual cloud layers at each level.
Visibility is in statute miles and fractions.
Absence of a visibility entry specifically implies visibility of more than 6 statute miles. S-BS means light snow and blowing snow. These elements are in symbols indentical to those used in surface observation reports and are entered only when forecast. 3325G35 means wind from 330 degrees at 25 knots gusting to 35 knots. This is also the same as surface observations.