Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
330 AM EDT Wed Aug 25 2021

Valid 00Z Thu Aug 26 2021 - 00Z Thu Sep 02 2021

Today's models and ensembles maintain reasonable agreement for the
overall pattern through the middle of next week.  Initially
moderate to brisk trades should gradually weaken as mid-latitude
high pressure tracks northeast for a time.  Some further weakening
should occur by early next week as an upper low settling
northeast/north of the state from around Friday into next week
encourages a surface trough to track over and north of the
islands.  In this time frame the trades may be weak enough to
allow for some sea breezes to focus shower activity instead of
over the prevailing windward/mountain locations.  Consensus still
shows the state within an east-west axis of relatively drier air
(precipitable water values up to 1-1.5 standard deviations below
normal at times) as greater moisture passes by to the north and
south.  Ensemble means show moisture trending toward climatology
by the middle of next week but the ECMWF/GFS are slower to raise
PWATs.  Most rainfall should be in the lighter half of the
spectrum given the below average moisture, though it remains to be
seen what influence the upper low northeast/north of the state may
have.  Recent trends have brought it a little closer to the
islands.

Rausch