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
   202311     1.76
   202312     1.79
   202401     1.60
   202402     1.33
   202403     0.97
   202404     0.53
   202405     0.00
   202406    -0.51
   202407    -0.93
   202408    -1.19