Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
350 AM EDT Mon May 09 2022

Valid 00Z Tue May 10 2022 - 00Z Tue May 17 2022

The latest models and ensemble means agree that high pressure
northeast of the state will maintain fairly brisk trades through
about Thursday.  Then trades should weaken from Friday into the
weekend and start to trend a little more southeasterly as the
eastern Pacific high weakens and a front sets up well to the
north/northwest of the islands, with the lighter trade regime
continuing through Monday.  Aside from a dissipated front's band
of moisture possibly raising rainfall totals a bit as it crosses
the area from northeast to southwest around Monday night-Tuesday,
precipitable water values near or slightly below climatology and
the brisk trades should lead to fairly light windward-focused
showers through late week.  By the weekend there is a general
signal that moisture may increase somewhat.  Latest ensemble means
still generally keep PWATs somewhat lower than the GFS/ECMWF but
appear to be nudging a bit toward the models.  Meanwhile the
lighter trades could allow for some sea/land breeze influence on
showers at some locations.  By Sunday-Monday the 00Z GFS diverges
from most other guidance for details of an upper trough/embedded
low forecast to evolve well northwest of the area, originating
from differences over the northwestern Pacific.  While a
combination of the GEFS mean and 00Z ECMWF/CMC plus their means
would be preferable for the overall pattern, thus far all but
perhaps the far western islands appear to be just far enough away
from this evolution that differences may not have too great of an
impact on the forecast.

Rausch