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
   202305     0.47
   202306     0.84
   202307     1.20
   202308     1.54
   202309     1.78
   202310     1.90
   202311     1.92
   202312     1.88
   202401     1.75
   202402     1.56