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
   201808     0.25
   201809     0.44
   201810     0.78
   201811     1.05
   201812     1.11
   201901     1.06
   201902     1.05
   201903     1.14
   201904     1.15
   201905     1.08