Are the impacts, from the La Niña that is forecast to develop later this year, going to be "typical" or will they be more of an outlier solution like that of the fading El Niño? (Differences Between 2015-16 El Niño and Previous Strong and Very Strong Events)
A comparison of the current NASA Sea Surface Height anomalies and those in May 1998 show some reason to keep an open mind. Note the large positive anomaly north of the equator; which is the same mass that was at least partially responsible for the 2015-16 El Niño being atypical.
And this area is literally outside of the Niño 3.4 box where SST anomalies are measured and used to gauge the presence and strength of ENSO events. Consequently, while the Oceanic Niño Index (ONI) may be showing cooling, this area will need to be watched as well.
In that context, even La Niña - Anything Goes for California Precipitation may not give enough clues for this coming winter. As always, it will be interesting and challenging. Stay tuned.
Jan Null, CCM
Golden Gate Weather Services