Latest seasonal predictions from NMME/IMME ensembles out today. Overall North Pacific pattern still looks very #LaNina-like: unusually wet PacNW and BC; unusually dry in SoCal & Lower Colorado Basin due to persistent NE Pacific ridging. HOWEVER... #WAwx #CAwx #AZwx (1/4) 
...However, exact position of N. Pac. ridge is key. Too far east, & CA stays dry, but far enough west & Sierra benefits from cold storms diving south. High confidence in winter ridge, but CA will be on razor's edge--exact position will dictate dry vs wet overall. (2/4)#CAwx
This is why seasonal prediction is hard. It's quite likely models are correct about strong, anomalous North Pacific ridge signal (mainly due to #LaNina). But that doesn't directly translate to CA precip--it only offers a modest tilt in odds toward dry winter. #CAwx #CAwater (3/4)
BTW...I still think folks claiming that ENSO is "largely meaningless" for CA precip are...well, simply not correct. There's lots of geophysical evidence it does matter. But what is true is that predictive signal is modest, noisy, & conditional...which complicates prediction.(4/4)
Addendum: there are some very early hints that things might change rapidly by next spring: coupled ocean-atmosphere models are hinting at an eventual transition to El Nino conditions. It's still far too early to read too much into that, but...stay tuned.
Also, to the extent that atmosphere/ocean scientists view the coupled ENSO system as a kind of "damped spring oscillator," it would make sense to expect a (possibly large) swing in the opposite direction now that the system has been in a La Nina state for 3 consecutive years.
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