Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
920 FXHW60 PHFO 240700 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 900 PM HST Thu May 23 2024 .SYNOPSIS... A high pressure ridge north of the islands will keep moderate to breezy easterly trade winds over the islands lasting into the middle of next week. Clouds and showers will favor typical windward and mountain areas, trending higher in the overnight to early morning hours. && .DISCUSSION... Satellite imagery this evening shows high level cirrus clouds spreading over the islands from west to east this evening. Fairly stable low level clouds are drifting over the islands in the moderate to breezy easterly trade winds. High level cirrus clouds may enhance sunrise and sunset colors over the next few days. Trade wind speeds will peak on Friday as the high pressure ridge builds slightly, and then decrease this weekend as the pressure gradient weakens a bit. Trade winds will drive these clouds up over windward island mountains into the middle of next week. Brief periods of showers remain in the forecast mainly over these windward and mountain areas, trending higher in the overnight to early morning hours. Drier leeward areas will see less clouds and only isolated showers due to the subsidence caused by the trade winds immediately downstream of the windward mountain ranges. Only subtle changes are expected in the day to day weather forecast for each island in a fairly stable trade wind weather pattern. The highest chances for clouds and showers statewide will continue to be over eastern Maui near Hana, and over the eastern slopes of the Big Island along the Hamakua Coast to Hilo to the Volcano. && .AVIATION... Moderate to breezy easterly trade winds will persist across the Hawaiian Islands into the weekend. Isolated to scattered showers will favor windward coasts and slopes, with greater coverage expected during the overnight hours. Brief MVFR conditions are possible in moderate showers. Otherwise, VFR conditions will prevail. AIRMET Sierra for mountain obscuration is in effect for windward areas of Maui and Oahu, and for all of Kauai this evening. Conditions may improve overnight, then an uptick in windward showers tomorrow morning may require AIRMET Sierra for more mountain obscuration across windward portions of some of the Hawaiian Islands. && .MARINE... High pressure will gradually build westward well to the north of the state tonight and Friday, strengthening the trade winds into the fresh to strong range across the island chain. A Small Craft Advisory (SCA) is now in effect for most waters around Maui County and the Big Island as well as the northwest Kauai waters through 6 AM Saturday. For the windiest waters around Maui and the Big Island the SCA extends through 6 PM Saturday. A trough of low pressure will amplify and linger west of the islands this weekend into early next week, resulting in a slight easing of the trades and a shift to a more east- southeasterly direction over the western end of the state. Moderate to strong easterly trades will prevail over the eastern waters. South shore surf will remain small and below the summer average through the middle of next week, with only small and inconsistent pulses of southwest swell expected. The next significant south- southwest swell (200 deg) appears to move in toward the end of next week. East shore surf will remain near the seasonal average through Friday, followed by a slight decrease this weekend through the middle of next week as the trades ease over and upstream of the islands. Surf along north shores will remain very small with a slight bump possible late Sunday through Monday. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 AM HST Saturday for Kauai Northwest Waters-Kaiwi Channel-Maui County Windward Waters. Small Craft Advisory until 6 PM HST Saturday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. Small Craft Advisory until 6 AM HST Friday for Big Island Windward Waters. && $$ DISCUSSION...Bohlin AVIATION...Powell MARINE...Jelsema