Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
350 AM EDT Wed Apr 16 2025

Valid 00Z Thu 17 Apr 2025 - 00Z Thu 24 Apr 2025

A pattern change is in store across Hawaii as a large upper 
trough approaches from the west, yielding lower mid-upper heights 
across Hawaii for the latter part of the week. At the surface, 
troughing will develop over the state and disrupt the trades. 
Winds are forecast to stay weak and allow for land and sea breezes
to dominate the pattern. Meanwhile a cold front will stall to the
west, ahead of which moisture will be drawn northward atop the 
islands and increase shower coverage. Precipitable water values 
could be near or over the 90th percentile for this time of year at
times. Plus the upper trough could allow for some instability to 
form to support potential thunderstorms. The wetter pattern should
begin Wednesday and peak across the state Thursday-Friday.

Over the weekend, the upper trough is forecast to weaken and pull
away, while Pacific surface high pressure develops well north and
allows for trades to slowly resume. This may be a somewhat wet 
trade wind pattern through early next week as moisture lingers. 
Then by around the middle of next week, there is a model signal 
for another upper trough to develop near the state, with another 
round of moisture potentially enhancing shower coverage once 
again.


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