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
   202307     1.06
   202308     1.24
   202309     1.55
   202310     1.89
   202311     2.10
   202312     2.07
   202401     1.91
   202402     1.73
   202403     1.50
   202404     1.22