FORECAST DISCUSSION

Synopsis

28 Mar 2024 13:23:00 GMT: Strong and gusty easterly trade winds are expected into Friday as high pressure strengthens north of the state. Showers will favor windward and mountain areas with some reaching the leeward areas. 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 and trade winds increase.

Discussion

28 Mar 2024 13:23:00 GMT: Guidance remains in good agreement and shows the pressure gradient steadily tightening across the region today as high pressure builds to the north. The easterly trades are responding and will become strong and gusty today through tonight as they peak. This has prompted a Wind Advisory for the typically windier areas of Maui County and the Big Island. In addition to the winds, spotty windward shower coverage is expected, especially overnight through the morning periods due to a sufficient amount of low- level moisture and a weak upper trough in the area. These showers will be brief with minimal accumulations anticipated. 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. A return of breezy to strong trades is anticipated through the first half of next week as high pressure builds north of the state (near 1050 mb). Model differences still remain with the GFS being stronger with the winds, while the ECMWF has a more moderate solution. Regardless of these differences, both depict an upper trough digging southward over the region creating an increased chance of heavier trade wind showers Monday through midweek.

Aviation

28 Mar 2024 13:23:00 GMT: Surface high pressure due N of the islands will support locally strong trade winds through Friday. Although the island atmosphere will be capped by a subsidence inversion based near 8 kft, showery low clouds will produce periods of MVFR VIS/CIG, mainly over windward slopes and coasts. Spatial and temporal coverage is not expected to be sufficiently significant to warrant an AIRMET for mountain obscuration, but AIRMET Tango for tempo moderate turbulence lee of the island terrain will remain in effect.

Marine

28 Mar 2024 13:23:00 GMT: Trade winds will increase into the strong to gale force range through the rest of the work week. A Gale Warning remains in effect from 6 AM this morning through 6 AM Friday morning for the Alenuihaha and Pailolo Channels. A Small Craft Advisory (SCA) remains in effect through tonight for all remaining coastal waters. Next week, another high pressure building in from the northwest is expected to continue the breezy trend across the coastal waters. Strong trades will create rough and choppy surf along east facing shores into next week. A small medium period swell from the north-northwest (330 degree) will arrive this morning, keeping surf elevated but far below advisory level across north and west facing shores. A series of small medium to long period northwest swells are expected through 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

28 Mar 2024 13:23:00 GMT: Wind Advisory from 6 AM this morning to 6 AM HST Friday for Lanai Mauka, Maui Windward West, Maui Leeward West, Kohala, Big Island Interior, Lanai Windward, Lanai Leeward, Maui Central Valley North, Maui Central Valley South, Windward Haleakala, South Haleakala, Big Island Southeast, Big Island North. Small Craft Advisory from 6 AM this morning to 6 AM HST Friday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Big Island Windward Waters. Small Craft Advisory until 6 AM HST Friday for Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Maalaea Bay, Big Island Leeward Waters, Big Island Southeast Waters. Small Craft Advisory until 6 AM HST early this morning for Pailolo Channel, Alenuihaha Channel. Gale Warning from 6 AM this morning to 6 AM HST Friday for Pailolo Channel, Alenuihaha Channel.

Footer

28 Mar 2024 13:23:00 GMT: DISCUSSION...Gibbs AVIATION...Birchard MARINE...Powell

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