FORECAST DISCUSSION

Synopsis

Trade winds will continue as high pressure persists to our north and troughing to our west moves away. Trade winds will be locally strong as clouds and showers favor windward and mauka areas through early next week. A pair of tropical cyclones expected to move westward across the central Pacific may affect the main Hawaiian Islands beginning late next week, possibly bringing more active weather.

Discussion

Deep troughing west of the main Hawaiian Islands has moved far enough away to allow trade winds to build westward across the state today. High pressure to our north will keep trade winds moderate to locally strong across the traditionally windy waters around Maui and the Big Island, and a Small Craft Advisory is in effect for those marine zones. Clouds and showers will favor windward and mauka areas through the weekend. A patch of showery low clouds embedded in the trades just upwind from the Big Island will increase cloud and shower coverage there tonight and the gridded database was altered accordingly. We expect the high to our north will keep moderate to locally strong trade winds in place, along with comfortable humidity levels and relatively few showers, through early next week. Beginning late next week, models show that a pair of tropical cyclones moving westward across the central Pacific may affect the island chain. However, it's still too early to tell what, if any, impacts could be seen in Hawaii. The National Hurricane Center in Miami is tracking these systems now, but the first of these systems could cross 140W into the Central Pacific Hurricane Center's area of responsibility as early as Sunday.

Aviation

VFR conditions will occur mostly across the terminals through the TAF period as northeasterly trade winds prevail. Satellite imagery indicates an area of low-level moisture moving toward the Big Island. This increased moisture will contribute to make showers more likely for PHTO with isolated to scattered MVFR this evening. Otherwise, brief MVFR conditions will be possible with showers for the windward and mountain areas.

Marine

A Small Craft Advisory is in effect for the traditionally windy waters around Maui and the Big Island, thanks to locally strong trade winds. This advisory is in effect through Friday afternoon, but will likely have to be extended in some form through the weekend. Short period trade wind swell will increase surf slightly along eastern facing shores Friday and into the weekend. Otherwise, no significant surf is expected through early next week. By the middle of next week, long period easterly swell generated by potential tropical cyclone activity east of Hawaii may begin to affect the state.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Friday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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DISCUSSION/MARINE...Powell AVIATION...Woodrum

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