


Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
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360 FXHW01 KWNH 170735 PMDHI Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 335 AM EDT Thu Apr 17 2025 Valid 00Z Fri 18 Apr 2025 - 00Z Fri 25 Apr 2025 A trough aloft is currently atop Hawaii and should remain over the state through late week. At the surface, troughing in place is disrupting the trades. Winds are forecast to stay weak in most areas and allow for land and sea breezes to dominate the pattern. Meanwhile a weakening 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, while the upper trough could allow for some instability to form to support potential thunderstorms. Thus a wetter pattern is likely on Thursday and Friday, with showers and storms likely peaking over the islands during the day because of sea breezes. 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 gradually 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, another upper trough is forecast to dig west of the state. This will once again cause the mean flow to veer for southeasterly/southerly winds that may be stronger this round. Moisture and showers are likely to increase once again as well. Tate