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
   202310     1.58
   202311     1.62
   202312     1.72
   202401     1.76
   202402     1.68
   202403     1.44
   202404     1.18
   202405     0.77
   202406     0.16
   202407    -0.60