717
FXHW01 KWNH 090700
PMDHI

Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
200 AM EST Tue Dec 9 2025

Valid 00Z Wed 10 Dec 2025 - 00Z Wed 17 Dec 2025

...Heavy rain possible in the western Hawaiian Islands early next
week...

Easterly trades start out the period with the usual windward
shower paradigm expected. A compact cut off low will lie east and
of the state today but is forecast to have minimal, if any,
impact on precipitation amounts across Hawai`i before it moves
east, out of the picture, in subsequent days.

A cold front moves into the western main islands late Wednesday
at the leading edge of a positively tilted trough, weakening the
trades. The guidance shows good agreement on this overall system,
allowing the front to generally move through the main Hawaiian
Islands into Friday. Showers/thunderstorms with brief moderate to
heavy rain are expected to accompany the frontal passage from
late Wednesday into Friday.

A pair of deep layer cyclones follows in its wake, also with good
guidance agreement. The polar front gets close enough to the
western main Hawaiian islands to keep the trades weak and
potentially lead to heavy rainfall Monday into Tuesday. The trend
in the boundary has been slightly eastward over the past 24
hours...will keep an eye on this in case the trend continues and
places more of Hawai`i at risk.

Roth

$$