Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
992 FXHW60 PHFO 021325 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 325 AM HST Tue Jul 2 2024 .SYNOPSIS... A broad high pressure ridge will remain locked in place north of the Hawaiian Islands into the upcoming weekend. Trade wind speeds will range from moderate to breezy for most days with slight decreasing wind speed trends from Thursday onward. Fairly stable conditions will produce mostly brief passing showers over windward and mountain areas. && .DISCUSSION... A broad subtropical ridge north of the island chain will keep moderate to breezy trade winds in the forecast lasting into the middle of the week with slight decreasing wind speed trends from Thursday onward. A slight ripple in the force is shown on infrared satellite imagery this evening as a band of clouds continues to move into the Big Island. This north to south oriented cloud band is associated with a weak low level trough riding into the islands on the easterly trade winds. Expect a slight increase in clouds and showers through the early morning hours across the windward slopes of Molokai, Maui and the Big Island, and then slightly increasing shower activity over windward Oahu and Kauai later tonight; as these unsettled clouds drift into the mountains of each island. A few high level cirrus ice crystal clouds are drifting over the state for the next few days, enhancing island sunrise and sunset colors. Otherwise mostly dry conditions will prevail this week with only brief passing showers over windward and mountain areas. Shower amounts will be limited due to the strong subsidence under this high pressure ridge pattern. Trade wind thermal inversion heights will range from around 4,000 to 6,500 feet with most windward areas only seeing isolated to scattered shower coverage, favoring the overnight to early morning hours. Some exceptions may include the eastern slopes of Maui, and the windward and Kona slopes of the Big Island where periods of passing rain showers will likely continue. && .AVIATION... Moderate to locally breezy trade winds will continue through tonight. A band of low clouds and showers will move from east to west across the state today, bringing some MVFR cigs/vsbys to windward areas as it moves through. Conditions will improve behind the band of clouds and showers, although some showery weather may linger across Kauai through the evening hours. AIRMET Sierra is in effect for mountain obscuration across windwardsections of Molokai, Maui and the Big Island. The AIRMET will likely need to be expanded to include Oahu later this morning. && .MARINE... High pressure north northeast of the state will bring fresh to strong trades through most of the week. By this weekend, the high will weaken and move off to the northeast as a trough approaches from the west and allow for trades to ease slightly across the local waters. A Small Craft Advisory has been extended through Thursday morning for the waters and channels around the Maui and The Big Island. Expect conditions in these typical windy areas to remain at or slightly below advisory levels Thursday afternoon into Friday. No significant south swells are expected during the forecast period. However, a series of small south-southwest and southeast swells will keep south facing shores from going flat. Flat to tiny surf conditions will continue along north and west facing shores through most of the week. East shore surf will be close to seasonal levels through late this week, as fresh to strong east northeast trades persist over and upstream of the islands. A fetch of strong northeast winds well off the California coast should bring a small, medium period, northeast swell Saturday into early next week. Some of this swell should wrap into select north facing exposures as well. Water levels running roughly 0.5 ft higher than normal around the Big Island combined with the new moon tides could cause minor flooding issues between July 2nd and July 6th with peak water levels expected on July 4th. Our last full moon, we did receive reports of some areas of the coastline becoming inundated with the high tide such as Coconut Island and Puhi Bay. A Coastal Flood Statement will likely be needed for the Big Island near the 4th of July. For the other islands, water levels are running just a touch above normal and will likely not reach our criteria of 1 foot above the Mean Higher High Water (MHHW). && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 AM HST Thursday for the windier areas around Maui and the Big Island. && $$ DISCUSSION...Bohlin AVIATION...Jelsema MARINE...JT