The first attachment shows the GFS forecast of zonal wind anomalies, updated February 25th (courtesy Carl Schreck). Moderate westerly wind anomalies have re-developed on/near the Dateline and are projected to continue into early March. If this were to develop as advertised, it would likely support further strengthening of the latest downwelling Kelvin wave and also allow SSTA near the Dateline to increase a bit.
The second attachment shows the GFS 180 hr forecast of SLP, wind speed, and precipitation for the North Pacific, updated Feb 25th (courtesy Surfline.com). Of some concern, high pressure is beginning to take over essentially the entire North Pacific. The GFS model is suggesting that this pattern will remain locked in place for the foreseeable future. This pattern is the opposite of what one would expect to see during a very positive PDO. If this pattern remains in place long enough (I would guess 2-3 weeks or more), it will cause the PDO index to drop. This is because this pattern would result in above avg SLP anomalies across the north Pacific and upwelling of cool water along the US west coast (NOTE: Prolonged N-NW winds along the US west coast will ALWAYS result in upwelling of cool water. See link). High pressure has indeed been in place off the coast of CA during the past few months, but it has been relatively weak, spotty, and small (mostly confined to So Cal). The high pressure systems that are currently developing are a whole different story. I'm not saying the PDO index will become negative, just that the positive values will weaken if this pattern persists. I suspect it would take at least a few months of this pattern to really drop the PDO index. This pattern is normally what one would expect to see around April or May (and we're in late February). Just something to watch. Also, the N PAC jet stream has also become a fragmented split flow mess (rather than a strong consolidated low latitude zonal flow). We'll have to see what happens in the coming weeks and what impacts the latest downwelling Kelvin wave has on things once it really begins to surface around late March/early April.
http://oceanography.asu.edu/Oc_Oct24_pos.pdfLMV,
I suspect that for at least the next week, the SOI will either remain around what it currently is or slowly drop (based on the GFS model and current observations).
EDIT: The third attachment shows the GFS hindcast of Jet Stream wind speed and height for Feb 25th (top), and the GFS forecast of Jet Stream wind speed and height for March 5th (bottom). Images courtesy of Stormsurf.com. The Jet Stream has become weak, split, and fragmented, supporting high pressure across the North Pacific.