CFSv2 Seasonal SSTs (clim19822010)
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
   201707     0.32
   201708     0.10
   201709    -0.13
   201710    -0.27
   201711    -0.44
   201712    -0.62
   201801    -0.66
   201802    -0.48
   201803    -0.14
   201804     0.21