Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
830 AM EDT Tue Oct 17 2017

Valid 00Z Wed Oct 18 2017 - 00Z Wed Oct 25 2017

...Chance of heavy rainfall increases by early to middle next
week...

The forecast period begins with benign weather across the Hawaiian
Islands with typical east to northeasterly trades as a subtropical
surface high pressure system extends eastward along the 32-degree
north latitude through the end of the week into the weekend.  Some
isolated showers can be expected especially near the favored
windward terrain areas.  By early into the middle of next week,
models and ensembles are indicating the possibility of
cyclogenesis as a cold front approaches from the northwest.  Given
the amplitude of the wave shown in the models this far out into
the future, it appears that a cyclone is likely to form early next
week with a cold front pushing across the Islands.  The flow is
expected to become more southeast to southerly by then with
increasing moisture content.  This would increase the possibility
of heavy rain moving across the Islands early into middle of next
week.

Kong