Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
344 AM EDT Wed Aug 09 2023

Valid 00Z Thu Aug 10 2023 - 00Z Thu Aug 17 2023

The very strong winds that the state has been experiencing will be
trending less extreme with time as the ridge to the north and
Hurricane Dora to the south maintain a westward course away from
the main islands.  Trades should decline to moderate strength by
late week and continuing into next week, with an upper weakness
(possibly containing one or more lows) passing through from the
northeast helping to weaken the surface gradient from the weekend
into Tuesday.  Today's guidance shows better agreement for surface
specifics than what was seen the past couple of days.  The upper
feature should continue west of the islands by next Wednesday,
with winds possibly rebounding a bit at that time.

Continue to expect the state to be within an east-west axis of
relatively dry air at least into early next week, though with some
gradual increase in precipitable water values.  There is a general
theme in the guidance of somewhat more moisture reaching the Big
Island and vicinity by next Tuesday-Wednesday as the upper feature
exits, but with noticeable differences for magnitude.  Yesterday
the 00Z GFS brought the most moisture by next Tuesday, tempered
somewhat in today's 00Z run.  Now the 00Z ECMWF is most generous
with moisture by next Wednesday.  Typically low predictability for
such details that far out in time, along with GFS trends, suggest
an average among the GFS and GEFS/ECMWF means as the best starting
point.  The general lack of moisture into early next week should
yield fairly light windward focused showers, with amounts possibly
increasing a little by the weekend and early next week with the
upper feature from the northeast tracking over/near the area.  The
Big Island could see additional modest increases in rainfall
toward midweek depending on how much moisture arrives.

Rausch