The Eastern Pacific - Pacific Crossing Notes: A Sailor's Guide to the Coconut Milk Run - page 249

Choosing a Weather Window
So what exactly should you watch for when planning this passage? Track the broader Pa-
cific weather picture carefully, paying special attention to two main factors: first, low pres-
sure systems and associated fronts moving east from New Zealand, and second, the South
Pacific Convergence Zone (SPCZ). Think of the SPCZ as the neighborhood troublemaker -
you'll want to keep an eye on its intensity and position at all times. If the SPCZ shifts south
of its usual haunt at around 10°S and combines with a front extending from one of those
New Zealand lows, you can expect a disturbance of the trade winds and squally conditions.
Keep in mind that global forecast models (such as NOAA's GFS GRIB forecasts) are not
very good at predicting the behavior of tropical phenomena such as the SPCZ. In fact,
GRIB files might show light winds when squalls of thirty to forty knots may be on the
prowl. Therefore, sailors should cull multiple weather sources, including synoptic charts
and satellite imagery. (See weather resources detailed in Atoll Cruising 101: The Tuamotus
and the Weather Notes chapter of this topic.) If you choose your weather window carefully,
this passage will likely turn out to be the pleasant hop you'd like it to be.