CFSv2 Seasonal SSTs (clim19822010)
first  rec: avg(lastbs-1, lastobs, CFSv2 month 1)
second rec: avg(lastbs, cfs month 1, CFSv2 month 2)
last   rec: CFSv2 month 9
other  rec: CFSv2 3-mo average
 TrgSeason    SST34
   201807     0.27
   201808     0.45
   201809     0.81
   201810     1.24
   201811     1.50
   201812     1.46
   201901     1.31
   201902     1.20
   201903     1.17
   201904     1.16