SC -- Grid and contour surface data
   SC parm map time <keywords>
   SC p1-p2 map t1-t2 <keywords>
Parameters:
  parm | T(F/C), TD(F/C), STR, ZS(m), PSL(mb), VOR, ABV, DVG,
         SPD(m/s), VIS(mi), PCP(in), SNO(in), THAE(K), THA(K),
         MIX(g/kg), GUS(m/s)
         for SVCA schema only: ZCL(ft), ZCM(ft), ZCH(ft)
         for ISFC schema only: CIGH(ft), ZCL1(ft), ZCL2(ft), PRE(mb)
  map | state P.O. abbreviation, DEF, MID, NA, SAT, USA (def=DEF)
  time | observation time, HH or HH:MM:SS (def=current)
  p1-p2 | parameter difference used in contouring
  t1-t2 | time difference used in contouring
Keywords:
  CINT= | contour interval (def=parm dependent)
  COLOR= | graphics color level; use negative number for dashed
           contours (def=2)
  DAY= | year and day, YYDDD; use YYDDD-YYDDD for day differences
         (def=current)
  GRA= | graphics frame number for display (def=current)
  GRIDF= | destination grid file number (def=from IGU SET)
  LAT=min max | latitude bounds; use when DEF is specified for the
                map parameter
  LON=min max | longitude bounds; use when DEF is specified for the
                map parameter
  MDF= | ISFC or SVCA schema MD file number; use two values (f1-f2)
         when contouring differences (def=last digit of current day)
  UNIT=A | contours data in American units (def)
      =M | contours data in Metric units
           This keyword is valid only for T and TD
Remarks:
  If you do not specify keywords CINT, COLOR, DAY, GRA, GRIDF, LAT,
  LON, MDF or UNIT, the string table is searched for strings of the
  same names.  If those strings exist, SC uses their values.  If
  keyword or string MDF is used, its value is stored and accessed in
  the string named SVCA.  If the command gives unexpected results, use
  TL to list the string table or TD ALL to delete it.

  Advection (ADV) or divergence (DVG) of a parameter is done by
  appending with ADV or DVG (e.g., TADV, SPDDVG).

  The time parameter defaults to the previous hour if the current time
  is less than 10 minutes past the hour.
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