Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
344 AM EDT Wed May 17 2023

Valid 00Z Thu May 18 2023 - 00Z Thu May 25 2023

Wednesday will begin a wetter shift to the weather pattern over
Hawaii as an upper trough west of the state moves eastward. Winds
turning more southerly ahead of the upper trough will help draw in
anomalously high tropical moisture (likely above the 95th
percentile for precipitable water). Thus, enhanced rainfall totals
are likely across the western islands in particular on Thursday
and Friday as showers increase in coverage and intensity, and the
local Weather Forecast Office has a Flood Watch in place for this
activity. The upper trough moving in could lessen or eliminate the
typical inversion, providing instability for some possible
thunderstorms. Some showers could make it to the eastern part of
the state but overall the best chances for heavy rain will be in
Kauai/Oahu. Shower coverage should gradually decrease through the
weekend as the weakening upper trough moves away and is replaced
by an upper ridge. This will shift the moisture plume west of the
state next week while surface highs build to the northeast and
northwest, creating a more typical and drier easterly trade wind
pattern.


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