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
   201908     0.00
   201909     0.07
   201910     0.20
   201911     0.32
   201912     0.26
   202001     0.19
   202002     0.12
   202003     0.15
   202004     0.21
   202005     0.24