Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
809 AM EDT Sun Aug 11 2019

Valid 00Z Mon Aug 12 2019 - 00Z Mon Aug 19 2019

Through late week/early next weekend the models and ensembles
still agree well with forecast details.  Expect light to moderate
trades to prevail during the first half of the week.  Winds may
weaken a bit over time, with some locations seeing sea/land breeze
influences.  Strengthening and westward expansion of eastern
Pacific high pressure will support stronger trades after early
Wednesday.  Trades may be on the brisk side for a time especially
around Friday.  Consensus shows a steady weakening of high
pressure to the north after Friday so trades should likewise trend
weaker by next weekend.  Through late week anticipate showers to
be fairly light given near to below average precipitable water
values and ridging aloft over the area.  Evolution of the trades
will support greater windward focus of any rainfall during the
latter half of the week.

By next weekend guidance generally suggests an evolution that may
promote some increase in rainfall.  To what degree is uncertain
though.  The upper ridge over/north of the region will likely
progress westward while higher precipitable water values move in
from the east.  Operational models diverge on how much moisture
reaches the main islands with the 00Z ECMWF much more aggressive
than the 00-06Z GFS runs.  For a single specific forecast the
GEFS/ECMWF means best represent the evolution toward greater
moisture with an intermediate solution between the operational
GFS/ECMWF extremes.

Rausch