487 FXHW60 PHFO 250632 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 832 PM HST Sun Feb 24 2019 .SYNOPSIS... A weak high northwest of the islands will move southeast and weaken. A surface trough east of the islands will weaken and move off to the east. The trailing end of a front over Kauai will move southeast through mid-week. Starting Wednesday night, a low will deepen northeast of the islands while a high far northwest of the islands builds south. The low will move rapidly away to the northeast on Thursday. && .DISCUSSION... Clouds and locally heavy showers over the southeast side of the Big Island have mostly dissipated. The surface trough that has been helping produce the showers on the Big Island is moving off to the southeast and is not expected to affect the island after tonight. A weak 1023 mb surface high lies about 700 miles northwest of Kauai near 31N164E. Northeast winds blowing out of the high are pushing a band of showery low clouds over Kauai this evening. This cloud band, the trailing end of a front, is rather shallow and producing only light windward showers. The band is expected to move slowly southeast, reaching Oahu Monday morning and Maui County Monday night. The band will temporarily stall over Maui County Tuesday as a wave forms along the band. Rainfall along the band will start off rather light, but a trough aloft may destabilize the atmosphere starting Tuesday evening and enhance showers. Starting Wednesday night, a low northeast of the area will dig southeast as a high northwest of the islands builds south along 165W. Strengthening north winds that will push the merging frontal moisture southeast of of the islands. The atmosphere will stabilize on Thursday as ridging builds over the area from the northwest.The north winds will carry cool dry air over the islands. && .AVIATION... A surface high far north-northwest of the islands will bring moderate northerly winds to the area. A band of moisture over Kauai will spread to the rest of the islands on Monday, bringing clouds and showers to mainly windward areas. Mainly VFR conditions will prevail across the sites, though brief MVFR ceiling may affect windward areas. Northeast winds will slowly clear away lingering moisture near the Big Island. Conditions are expected to improve through the rest of this evening and will allow for the cancellation of AIRMET SIERRA for mountain obscuration on the Big Island. && .MARINE... High pressure far northwest of the state will maintain moderate to fresh northeast winds through Tuesday. A low to the east and a high to the northwest produce widespread fresh to strong north winds Wednesday through Thursday. A ridge of high pressure moving south toward the state on Friday will briefly relax the winds across the state. Another front may bring fresh to strong northerly winds next weekend. Small surf is expected on all shores through tonight, but a new moderate mid-period northwest swell will be filling in through the day Monday. A larger long-period northwest swell will begin to fill in on Tuesday and peak Wednesday or Wednesday night near warning levels. The combination of this large northwest swell, large wind waves associated with fresh to strong north winds, along with a short period north swell, will lead to rough conditions that will require a Small Craft Advisory (SCA) for most waters and possibly a High Surf Advisory (HSA) for east facing shores as well. Winds and seas should decrease below SCA levels by late Friday or Friday night, with HSA level surf possibly holding along east facing shores exposed to the declining north swell into early Friday. && .HFO WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Donaldson AVIATION...Hui MARINE...Gibbs