Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
257 AM EDT Mon Sep 20 2021

Valid 00Z Tue Sep 21 2021 - 00Z Tue Sep 28 2021

The weather pattern is expected to be relatively uneventful across
the Hawaii domain for the upcoming week with surface high pressure
generally being centered near 35 to 40 degrees north.  Aloft, an
inverted trough is forecast to slowly track westward through the
week, with the GEFS mean slightly faster than the EC mean.  By the
middle to end of the week, a cold front is expected to stall to
the north of the Islands before dissipating, with perhaps some
weakening of the surface pressure gradient and lighter trade winds.

It appears the best moisture and lift associated with the weak
upper trough should remain south of the Islands, with perhaps some
increase in trade wind induced showers on Tuesday and Wednesday
across the Big Island.  There may be a more organized round of
rainfall on Sunday/Monday as an easterly wave approaches the
state.  Otherwise, easterly flow on the order of 15 to 20 mph can
be expected for most of next week with windward showers.

Hamrick