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
   201804    -0.50
   201805    -0.21
   201806    -0.07
   201807     0.00
   201808     0.02
   201809     0.10
   201810     0.18
   201811     0.21
   201812     0.16
   201901     0.12