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
   202504    -0.07
   202505    -0.10
   202506    -0.01
   202507     0.07
   202508     0.10
   202509     0.14
   202510     0.17
   202511     0.21
   202512     0.34
   202601     0.59