Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
352 AM EDT Thu Aug 26 2021

Valid 00Z Fri Aug 27 2021 - 00Z Fri Sep 03 2021

Latest guidance shows similar ideas for the evolving pattern
through the period with typical day-to-day continuity adjustments.
 From late this week into the weekend moderate to brisk trades
will support mostly windward/mountain showers.  Then trades will
weaken as a developing surface trough, underneath an upper low
that settles northeast/north of the state for a few days, tracks
westward over and north of the islands during the early-middle
part of next week.  The lighter background flow will allow for
more sea/land breeze shower focus.  Guidance consensus shows the
trades picking up again next Thursday as the surface trough
departs.  Models and means agree on precipitable water values
staying below climatology through at least Tuesday as separate
areas of moisture pass by to the north and south of the state, so
most rainfall should be on the lighter side during the next few
days.  By Wednesday-Thursday the ensemble means show moisture
increasing to a greater extent than in the 00Z GFS/ECMWF.  At
least some increase of moisture is plausible given the
southwestward shearing of the upper low to the west of the main
islands in this time frame.

Rausch