Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
199 FXHW60 PHFO 282016 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 1016 AM HST Tue May 28 2024 .SYNOPSIS... High pressure to the north will maintain moderate to locally breezy trade winds through early next week. Showers will favor windward slopes and coasts, especially during the overnight and early morning hours. A trough aloft will move over the islands Friday through early next week, bringing an increase in trade wind shower coverage and intensity. && .DISCUSSION... This morning`s satellite imagery shows some scattered showers across the state mainly over windward areas this morning. A surface trough located west of Kauai is producing scattered thunderstorms roughly 180 miles west of Kauai. These thunderstorms and heavy showers are expected to remain west to northwest of Kauai. The trough west of the state is weakening the trades a touch around Kauai and Oahu with moderate east to east-southeast winds. Meanwhile over on the eastern half of the state, we are seeing breezy easterly trades. For rest of the day today and through Wednesday, we should see fairly similar weather conditions with scattered showers at times. Starting Thursday, the trough will drift further away from the area and we should see our breezy east-northeast trade winds across the state. Mostly dry conditions are expected during the day Thursday with a few isolated showers over windward areas. An upper level trough will begin to approach the state from the northeast on Friday, which should bring some instability and will increase shower coverage across the state especially windward areas. At this time, no significant impacts are expected but windward areas could become quite showery at times. Some of the showers should make its way over leeward areas as well. Breezy east to east-northeast trades will continue to persist through the weekend. && .AVIATION... Moderate to breezy trade winds will bring clouds and showers with periodic MVFR conditions to windward and mauka areas. Otherwise VFR conditions will prevail. AIRMET Sierra is in effect for mountain obscuration across windward Big Island and N through SE sections of Maui through Kauai. Conditions for moderate low-level turbulence downwind of island terrain look marginal through the next couple of days and AIRMET Tango may be needed on and off through the period. Light icing will be possible around FL180 and FL250 across the state today, due high clouds streaming in and an upper level low off to the northwest. && .MARINE... Fresh to strong easterly trades will continue through the week as the surface ridge remains positioned north of the state. The strongest winds are expected over the windier waters and channels from Oahu to the Big Island, where a Small Craft Advisory remains in effect. Wind across the Kauai waters will fluctuate between east and east-southeast through Wednesday due to a persistent surface trough to the west. A shift out of the east-northeast is expected beginning around Thursday as the trough weakens and drifts away from the region. Surf along exposed south-facing shores will remain small throughout much of the week, due to a combination of background south-southwest and southeast swell energy. An upward trend is expected from Friday through the first week of June due to an active pattern evolving within our swell window near New Zealand. Altimeter and ASCAT passes over the past couple of days showed a broad swath of gale-to storm-force winds with seas up to 30 feet focused at the state within the 190-200 degree directional bands. This will mark the beginning of a long-lived event with additional reinforcements expected within the same area over several days. Surf along exposed east-facing shores will remain small and choppy throughout the week as the trades persist. Surf along north-facing shores will remain near the summertime average each day. Guidance depicts a small, long-period swell arriving early next week from a gale that is forecast to track northeastward today over the far northwest Pacific near the Kuril Islands. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST Wednesday for Kaiwi Channel- Maui County Windward Waters-Maalaea Bay-Pailolo Channel- Alenuihaha Channel-Big Island Windward Waters-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...Kino AVIATION...Farris MARINE...Vaughan