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
   202312     1.84
   202401     1.55
   202402     1.07
   202403     0.62
   202404     0.17
   202405    -0.27
   202406    -0.67
   202407    -0.99
   202408    -1.20
   202409    -1.37