CFSv2 Seasonal SSTs (clim19912020)
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
   202401     1.71
   202402     1.42
   202403     1.06
   202404     0.64
   202405     0.05
   202406    -0.52
   202407    -0.95
   202408    -1.22
   202409    -1.46
   202410    -1.72