NOAAs ONI-value for October-November-December (OND) was -0,8
which is the same as for the periods ASO and SON. If the value for November-December and January is -0,5 or lower a full-fledged La Niña will be declared. The combined ONI-values for November and December were -1,65
(-0,93 and -0,72 respectively).
This means that the monthly ONI-value needs to be just +0,16
to get an ONI-value less than -0,5 for the period NDJ. To boom the La Niña conditions for sure the January value needs to be at least +0,21
. Such a high value seems extremely unlikely IMO.
From the monthly ONI-values in the attached link with values back to 1950 there haven't been ANY
case in which the monthly ONI-value have differed as much as 0,93. The best I could find was May-June 1998 which saw a difference by 0,82
. Wrt the current statistics I daresay that there is a 99% likelihood
that NOAA will declare a full-fledged La Niña for the season 2016/2017. What do you think guys?http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/detrend.nino34.ascii.txt