SP -- Plot Surface Data
  SP parm map time <keywords>
  SP p1-p2 map t1-t2 <keywords>
Parameters:
  parm | PLOT, T(F/C), TD(F/C), WIN(ddff,ff(m/s)), ZS(m), PSL(mb),
         VIS(mi), PCP(in), SNO(in), ID, CLD, WX, WXS, SPD(m/s),
         GUS(m/s), THAE(K), THA(K), MIX(g/kg)
         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 plotting
  t1-t2 | time difference used in plotting
Keywords:
  COLOR= | graphics color level for display (def=3)
  DAY= | year and day, YYDDD; use YYDDD-YYDDD for day differences
         (def=current)
  GRA= | graphics frame number for display (def=current)
  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 plotting differences (def=last digit of current day)
  UNIT=A | plots in American units (def)
      =M | plots in Metric units
           This keyword is valid only for T and TD
Remarks:
  If you do not specify keywords COLOR, DAY, GRA, LAT, LON or MDF,
  the string table is searched for strings of the same names.  If
  those strings exist, SP 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.

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