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
   202402     1.40
   202403     0.94
   202404     0.33
   202405    -0.24
   202406    -0.86
   202407    -1.31
   202408    -1.66
   202409    -1.94
   202410    -2.19
   202411    -2.39