Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
818 AM EDT Thu Aug 15 2019

Valid 00Z Fri Aug 16 2019 - 00Z Fri Aug 23 2019

Upper ridging is forecast to remain in place across Hawaii through
the weekend before a broad upper-level weakness develops just east
of the state early next week. As relatively strong surface high
pressure well northeast of the state weakens by early next week,
trades (initially 15-20 kt) should weaken somewhat. Scattered
windward/mauka showers should persist through the weekend in a
near-normal precipitable water environment. Confidence in the
eventual track of a tropical wave toward Hawaii early next week
remains relatively low, with solutions diverging on the exact
track of the system. Nonetheless, models suggest that at a minimum
an increase in moisture is possible by Tue-Wed as the wave
approaches/passes the state, with some increase in coverage of
showers possible. Given the poor confidence in the track of the
wave, the specifics of any increase in shower potential remain
elusive at this time. By mid to late next week, ensemble means all
generally show the broad upper trough weakening with upper ridging
once again becoming established north/northwest of Hawaii,
bringing a gradual return of more typical trades.

Ryan