FORECAST DISCUSSION

Synopsis

27 Mar 2024 13:19:00 GMT: Breezy easterly trade winds will become strong and gusty later today through the second half of the week as high pressure strengthens north of the state. Windward shower coverage may increase through this period, with some showers occasionally making it to leeward areas of the smaller islands. Drier and more stable conditions will return over the weekend, with the easterly trades easing into the moderate to breezy range. Rainfall chances could trend up again early next week as an upper disturbance moves through.

Discussion

27 Mar 2024 13:19:00 GMT: Guidance remains in good agreement through the second half of the week and shows high pressure building north of the state. The easterly trades will respond and become strong beginning later today, then likely strong enough for localized wind advisories through the day Thursday over the typically windier locations of Maui County and the Big Island. In addition to the strengthening winds, windward shower coverage could trend up due to a combination of a weak mid- to upper-level trough and a sufficient amount low-level moisture in the area. Some of these showers will manage to make it over to leeward areas of the smaller islands, especially overnight through the mornings. Rainfall accumulations should remain light. Drier and more stable conditions will briefly return over the weekend as upper heights rise and PWs dip to around an inch. Trade winds are expected to ease into the moderate range due to a weakness forming in the ridge as a front passes to the north. The forecast confidence lowers early next week due to significant differences shown between the various model solutions. While the GFS solutions are more aggressive and depict the tail-end of the aforementioned front moving through the area with strong northerly winds trailing it, the ECMWF shows it hanging up to the north with easterly trades holding (agrees with the blended guidance). Regardless of these differences, the attendant upper trough digging southward over the region drawing moisture into the area should be enough to support a transition to a wetter pattern Monday through midweek.

Aviation

27 Mar 2024 13:19:00 GMT: Moderate to breezy easterly trades will continue through the remainder of this morning as surface high pressure remains anchored to the north of the state. Scattered showers will mainly be confined to windward locations with the occasional spill over to leeward sides. Brief periods of MVFR ceilings and visibility may occur with any of the more robust showers. By this afternoon, trades will strengthen further and become windy at times. This stronger flow will persist this evening into tonight and bring scattered to numerous showers to windward locations. AIRMET Sierra has been issued above 2000 feet for north through east sections of Oahu due to tempo mountain obscuration from low clouds and showers.

Marine

27 Mar 2024 13:19:00 GMT: High pressure north of the main Hawaiian Islands will move eastward and strengthen over the next few days, resulting in increased trade wind speeds across local waters through the rest of the work week. The Small Craft Advisory (SCA) remains in effect for the typical windy zones around Maui County and the Big Island but has been expanded to include windward and leeward waters around Maui County and Oahu. Strong trades will create rough and choppy surf along east facing shores which will continue into next week. Moderate west- northwest (310 degree) swell will gradually decrease today. Expect additional small northwest (310-320 degree) swells from Thursday into early next week. Mainly background surf will continue for south facing shores through the weekend with some long period energy arriving early next week.

HFO Watches/Warnings/Advisories

27 Mar 2024 13:19:00 GMT: Small Craft Advisory until 6 PM HST Thursday for Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Footer

27 Mar 2024 13:19:00 GMT: DISCUSSION...Gibbs AVIATION...Thomas MARINE...Powell

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