Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
259 AM EST Tue Nov 28 2023

Valid 00Z Wed Nov 29 2023 - 00Z Wed Dec 06 2023

...Heavy Rain and Flash Flooding possible this week across much of
Hawaii...

There continues to be excellent agreement that a Kona low will set
up west of Hawaii this week, bringing potential for widespread
heavy rainfall and thunderstorms Tuesday-Friday to much of the
state. The guidance shows precipitable water values surging up to
two or more standard deviations above normal, increasing the
threat for flooding and flash flooding. Despite the large scale
agreement, there continues to be quite a bit of uncertainty in the
details which has implications for total rainfall amounts with
some of the guidance suggesting the heaviest rains may actually
stay north of the island chain. The 00z run of the CMC is
displaced a bit east of the better consensus, but not totally out
of the realm of possibilities. Still, at this point, prefer a
non-CMC solution. The upper low should weaken and slowly begin to
drift east Friday-Saturday. Rainfall this weekend should trend
lighter across Hawaii, but still some potential for locally heavy
rain as the upper low lingers. Trade winds should shift back
easterly and strengthen early-mid next week.

Santorelli