Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
473 FXHW60 PHFO 080042 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 242 PM HST Fri Feb 7 2025 .SYNOPSIS... Gentle to locally moderate ESE trades will persist through midweek next week with increasing stability and an influx of drier air helping to limit shower activity. A slightly stronger easterly flow across the eastern half of the state will maintain a more typical trade wind shower regime, while a weaker ESE flow will bring more of hybrid shower pattern to the western half. Rain chances will increase from the west late next week. && .DISCUSSION... Current radar and satellite imagery show clouds with isolated showers building over windward slopes and a few leeward and interior areas as diurnal heating has helped sea breezes to develop across the better wind-protected areas. Gentle to locally breezy ESE trade winds will persist through mid week next week as high pressure strengthens to the northeast and fills in across the state. With the increasing stability from this surface ridge and weak mid-level ridging building in from the west combined with drier air filtering in on the trades, shower activity should be minimal through the weekend. As the island chain remains on the southwestern periphery of the surface high through the weekend and into next week, trades will generally be out of the ESE. Winds across the western end of the state will become lighter and somewhat variable... typically displaying more of a southerly component, while the eastern end of the state will be impacted by slightly stronger easterlies. The weaker winds across the western half may allow for isolated sea breeze activity with afternoon clouds and showers forming over a few leeward and interior areas, and the stronger winds across the eastern half will yield a more typical trade wind weather regime with showers favoring windward areas overnight and leeward slopes of the Big Island each afternoon. The ESE flow for the western half of the state may also allow island plumes (downstream convergence from island terrain) to bring showers to leeward areas at times. As mid level ridging edges in from the west and strengthens through midweek next week, overall shower development will continue to be suppressed, but periodic pockets of moisture may bring brief upticks in shower activity. The weather pattern looks to become more active for the latter part of next week as model guidance shows a deep low forming well to the north of the state that may drag some semblance of a front across the western end of the island chain Thursday night into Friday. While this is still pretty far out and model discrepancies remain, there is a signal for moisture being drawn up in the SSW flow ahead of this feature that could help to increase the chance of showers ahead of and along any potential frontal boundary Thursday night into Friday. As of now, the forecast leans towards moderate chances of Valentine`s Day showers with breezy southwesterlies veering more northeasterly from Oahu westward through Saturday (Day 8). && .AVIATION... A ridge remains just north of the islands, and will maintain a weak east to east-southeast flow over the islands. Winds will be light enough for some localized land and sea breezes across the islands, which could bring some afternoon clouds and isolated showers to interior sections. Otherwise, clouds and isolated showers will be focused over the typical windward sides of the islands. Some brief MVFR ceilings and visibility in showers are possible, mainly during the afternoon and evening hours. Otherwise, VFR conditions are expected to prevail. No AIRMETs in effect, and none are expected through tonight. && .MARINE... A weak surface ridge is shifting north and is expected to stall to the north through midweek. Light to moderate east-southeast winds are expected across the chain with the exception of windier areas around Maui and the Big Island where moderate to fresh winds are expected to develop tonight. A lingering medium period northeast swell will continue to decline through tonight. In the meantime the long- period northwest swell is currently peaking. A High Surf Advisory (HSA) is in effect for north and west facing shores through Saturday. The long-period northwest swell mentioned above is generating surf heights of 15-24 feet along north shores of Niihau, Kauai, Oahu, Molokai, and Maui. A slightly smaller NW swell is expected from Saturday night into Monday. A larger WNW swell looks likely Tuesday and Wednesday of next week once again bumping up surf heights. Along east facing shores the HSA has been cancelled as surf is continuing to decline below criteria. No significant surf is expected along south facing shores. A Small Craft Advisory (SCA) for combined seas of 10 feet or greater remains in effect for zones exposed to the increasing NW swell and lingering NE swell as well as the typically windier areas surrounding Maui and the Big Island. && .HFO WATCHES/WARNINGS/ADVISORIES... High Surf Advisory until 6 AM HST Saturday for Niihau-Kauai Leeward-Waianae Coast-Oahu North Shore-Maui Windward West-Kauai North-Molokai Windward-Molokai North-Molokai West-Windward Haleakala. Small Craft Advisory until 6 AM HST Saturday for Kauai Northwest Waters-Kauai Windward Waters-Kauai Leeward Waters-Kauai Channel- Oahu Windward Waters-Oahu Leeward Waters-Kaiwi Channel-Maui County Windward Waters-Maalaea Bay-Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...Farris AVIATION...M Ballard MARINE...Walsh/JVC