Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
249 AM EST Mon Jan 30 2023

Valid 00Z Tue Jan 31 2023 - 00Z Tue Feb 07 2023

Heavy rain and thunderstorms are likely to continue across Hawaii
through at least today, as a closed low just west Kauai will
remain in place and continue to draw in deep tropical moisture as
well as provide instability with a removed inversion given the
lowering heights aloft. Moisture levels will be quite high with
precipitable water values likely to remain over the 90th, even
95th, percentile. Meanwhile a surface trough will continue to
focus this moisture and gradually drift west over the next couple
days. All islands may be at risk of seeing very heavy rain amounts
and additional instances of flooding--over the eastern islands
where moisture levels are maximized and the western islands
particularly as the trough passes over. Thus the Honolulu Forecast
Office has a Flash Flood Watch in place for much of the state.
Additionally, the summits of Mauna Kea and Mauna Loa could see
some additional snow given the lower heights of the trough/low
causing colder air in these highest elevations, and Winter Storm
Warnings remain in effect.

By Tuesday and beyond, models generally indicate that the closed
upper low should drift a bit west away from the state but be slow
to erode. This will lead to less support for the heaviest rainfall
amounts, but above average moisture looks to stay in place through
midweek and beyond, but likely to a lesser extent. After a period
of some weaker overall winds around midweek, the surface pattern
looks favorable for more typical easterly winds to form by later
in the week with a high to the north. Additionally, a cold front
or two may approach Hawaii and help focus moisture, but with some
uncertainty in timing and with how far the fronts sink south.
Overall a wet trade wind pattern looks to be in store through the
rest of the week.

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