687 FXHW60 PHFO 060610 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 810 PM HST Sun Aug 5 2018 .SYNOPSIS... A high pressure system northwest of the Hawaiian Islands will keep moderate to locally breezy trade winds in the forecast for the next few days. Drier and more stable air moving across the region will keep shower coverage limited to mainly windward and mountain areas through Tuesday afternoon. Hurricane Hector will cross into the local region from Tuesday night into Thursday, though it remains too early to determine precise impacts on island weather at this time. Hector will likely clear the region by Friday, with typical summertime trade wind weather heading into next weekend. && .DISCUSSION... A strong 1034 MB surface high center roughly 1600 miles northwest of Kauai will continue to produce moderate to locally breezy trade winds across the region for the next few days. Increasing downward motions, or subsidence, in the upper atmosphere has strengthened the trade wind inversion over the state decreasing shower activity into the isolated to scattered range. A drier trade wind weather pattern will last through at least Tuesday afternoon. Satellite imagery this evening supports the drier weather forecast as a broad area of more stable stratocumulus is shown moving across the state. Hurricane Hector will move into the Central Pacific basin over the next few hours with the current forecast track keeping the center of Hector just south of the Big Island. However, hurricane impacts extend beyond the center of the low, and the average track errors of the hurricane this far out are up to 150 miles on either side of the forecast track. Hector will move into the local region around Hawaii from Tuesday night into Thursday. Weather impacts for each island remain highly dependent on the hurricane intensity and track. Much of the local weather impacts will need to wait until the hurricane gets closer to the islands, as slight track changes over time can produce larger than normal forecast differences. For now, we continue to forecast numerous rain showers moving into the eastern side of the Big Island by Wednesday morning, as deeper tropical moisture enhances showers along the eastern slopes of Maunakea and Maunaloa. Please continue to closely monitor this major hurricane as it moves closer to the state. Tune in to your favorite TV and radio stations, or go online to find the latest official forecasts produced by local Meteorologists from the Central Pacific Hurricane Center at weather.gov/cphc with local weather impacts at weather.gov/hawaii as they become available. The National Weather Service encourages everyone review their hurricane preparedness plans. A guide for hurricane preparedness can be found at www.ready.gov/hurricanes. The State of Hawaii and each county also have preparedness information specific to the islands. Friday through Sunday, Hector will exit the region, and we will return to a stable and mostly dry trade wind weather pattern. Scattered showers will tend to favor windward and mountain slopes through next weekend. && .AVIATION... A surface high far northwest of the area will maintain locally strong east winds through tomorrow and keep the atmosphere stable. The strong winds and strong and low temperature inversions will combine to promote moderate turbulence west of the mountains, so AIRMET Tango remains in effect. VFR conditions will prevail, but there will be isolated MVFR ceilings and visibilities, over mainly northeast sections of the islands. AIRMET Sierra for MTN OBSC may be needed at times. && .MARINE... A Small Craft Advisory (SCA) remains posted for the typically windier waters near Maui County and the Big Island through Tuesday, due to strong high pressure far north-northwest of the state. A series of small south swells are expected through Wednesday. A small north swell is expected to arrive late Tuesday, peak Tuesday night and Wednesday, then lower gradually Thursday and Friday. Hurricane Hector is expected to cross from the East Pacific into the Central Pacific in the next few hours, and the Central Pacific Hurricane Center will begin advisories on the system at 11pm HST. Swells generated by Hector are expected to reach the eastern coastal waters on Monday and then gradually increase through Wednesday. This will result in gradually increasing surf along the east facing shores of the Big Island over the next few days, before the swell and resultant surf transition to the south during the second half of the week. Based on the latest guidance, large surf is expected over exposed shorelines on the Big Island and East Maui by the middle of the week. Shorelines of the smaller islands will be less impacted as they will be somewhat shadowed by the Big Island and Maui until Hector moves further west. We are also entering a period of high astronomical tides this week, so low lying coastal areas may have some coastal inundation issues. Stay tuned for the latest updates on Hector and its potential impacts on winds, seas, and surf across the area. See the latest Oahu Surf Discussion (SRDHFO) for additional details on surf and swell. && .FIRE WEATHER... Wind speeds will gradually decrease for Monday as high pressure north of the islands weakens. However, breezy winds will hold with wind gusts of around 35 mph over and downwind of leeward terrain. A drier air mass will continue to move in from the east tonight, bringing lower humidity trends and decreasing rainfall, especially over leeward areas. Although critical fire weather thresholds will likely not be crossed during the next couple of days, many of the ingredients will remain in place for elevated fire activity. Hurricane Hector will be crossing the region during the middle of the work week, though it is still too early to determine specific impacts on local weather. That said, those areas not directly impacted by Hector could see continued dry conditions with an increase in trade winds. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST Tuesday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...Bohlin AVIATION...Donaldson MARINE...M Ballard FIRE WEATHER...Wroe