Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
338 AM EDT Wed Oct 13 2021

Valid 00Z Thu Oct 14 2021 - 00Z Thu Oct 21 2021

Latest guidance continues to show the trades becoming
progressively weaker with time between now and the middle of next
week.  Fairly brisk trades as of Wednesday will weaken later in
the week as a cold front partially erodes the surface ridge north
of the state.  Then trailing high pressure to the north of the
state over the weekend will weaken quickly as a cold front
associated with a strong northeastern Pacific storm drops
southward, supporting still lighter trades.  Models/means agree on
precipitable water decreasing to below average values into the
weekend and now are more similar than they were yesterday for the
first half of next week.  Although there is somewhat better
clustering toward a northeast-southwest upper trough/shear axis
over or near the state, consensus now shows PWATs remaining near
their weekend values into midweek.  On a relative basis the higher
moisture values should be over the southern Big Island.  The
decreasing/below average moisture should favor mostly light to
moderate showers over favored windward and mountain terrain (with
some rain occasionally straying leeward), though the upper
weakness could support a little enhancement at times.  Shower
focus could change somewhat toward midweek depending on exactly
how weak the trades become.

Rausch