FXHW60 PHFO 240905 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 1105 PM HST Fri Aug 23 2024 .SYNOPSIS... Breezy trade winds will continue through tonight, with showers favoring windward and mauka locations. The Central Pacific Hurricane Center continues to closely monitor Tropical Storm Hone far east-southeast of the Big Island moving westward. On its current track, Hone is expected to pass near or south of the Big Island Saturday night into early Sunday bringing the potential for heavy rainfall, damaging winds, and large surf. Expect strong and gusty easterly winds to continue Sunday into Monday as Hone passes south of the smaller islands. A brief return of moderate to breezy trade winds is expected late Monday through Wednesday of next week as Hone tracks away from the state and Tropical Cyclone Gilma approaches the region from the east. && .DISCUSSION... A high pressure system far north of the Hawaiian Islands and Tropical Storm Hone passing near the southern slopes of the Big Island this weekend will keep strong and gusty winds in the forecast into Monday. Cloud bands moving in ahead of Tropical Storm Hone will continue to produce periods of showers mainly over windward and mountain areas into Saturday, these showers will favor the overnight to early morning hours. Our attention then turns to Tropical Storm Hone. The latest Central Pacific Hurricane Center forecast shows Tropical Storm Hone briefly becoming a hurricane Sunday night as it passes south of the smaller islands. Forecast confidence in Hone impacting our local weather continue to increase, regardless of its exact development and track. The latest forecast guidance continues to show winds across the state increasing on Saturday as the gradient tightens ahead of Hone. Strong downslope winds are likely across the smaller islands Saturday morning through Sunday night, with gusts to 45 mph possible, so a Wind Advisory has been issued for these areas. Drier air is also expected to filter in across the state on Saturday ahead of Hone. The combination of the dry air mass and strong downslope winds will bring elevated fire weather concerns to leeward portions of the islands. Afternoon relative humidity remains marginal tomorrow, but given past events with passing tropical systems a Red Flag Warning was issued for leeward areas Saturday afternoon. The threat of elevated fire weather concerns decrease late Saturday as moisture from Hone starts to move into the state. Based on the current forecast track for Hone, strong and gusty winds associated with the system will begin to impact the Big Island Saturday evening, with widespread gusts up to 50 mph likely late Saturday through early Sunday. The strongest gusts are expected around South Point/Ka Lae, as well as downslope from Mauna Kea, Mauna Loa, the Kohala Mountains, and the Humuula Saddle, which could see gusts as high as 60 mph. The Central Pacific Hurricane Center keeps the Tropical Storm Warning in effect for the Big Island. Now is the time to finalize your emergency plans and supplies and take the necessary actions to protect your family and secure your home or business. Deep tropical moisture will move in from the east on Saturday into Sunday increasing the potential for heavy rainfall across windward and southeast areas of the Big Island. As rainbands associated with Tropical Storm Hone move in late Saturday into Sunday, heavy showers and thunderstorms will increase the potential for localized flash flooding. A Flood Watch remains in effect for the Big Island starting Saturday afternoon. Shower coverage then expands down the island chain Sunday into early next week as Hone passes to the south. A brief return of moderate to breezy trade winds is expected late Monday through Wednesday of next week as Hone tracks away from the state and Tropical Cyclone Gilma approaches the region from the east. Forecast confidence, with regards to impacts to our local weather, remains very low late next week due to significant differences shown between the various sources of guidance as Gilma approaches the region. For further details on Hone's development, please refer to the latest forecast issued by the Central Pacific Hurricane Center at www.hurricanes.gov. Note that public and marine forecasts from WFO Honolulu will be updated on a modified schedule, in conjunction with the latest CPHC forecast issued at 5 AM/PM and 11 AM/PM HST. && .AVIATION... Breezy to windy trades are continuing across the island chain this evening. Low cigs and SHRA embedded within these trades will continue moving into windward and mauka locations with some spillover into leeward areas. MVFR conds are to be expected. As we head into the weekend, the forecast will be primarily driven by Tropical Storm Hone. Currently on a westward track and is expected to pass near the Big Island Saturday night and Sunday. As rain bands associated with Tropical Storm Hone move in Saturday and Sunday, +RA, TSTMs, reduced vsbys and strong winds will be possible at times, particularly over the eastern end of the state. AIRMET Sierra remains in effect for mtn obsc for all islands. AIRMET Tango remains in effect for mod low- level turb blw 080 downwind of island terrain. This AIRMET will most likely be needed into early next week. Over the next couple of days, additional AIRMETs may be issued to account for sustained 30kt winds over portions of the area, as well as potential IFR conds as rain bands move through. As Tropical Storm Hone approaches the islands, aviation interests should also closely monitor updates to TC SIGMET Whiskey this weekend. && .MARINE... An area of surface high pressure north of the islands will allow locally strong trades to prevail tonight. A Small Craft Advisory has been expanded to include all waters, with the exception of those off Big Island windward. By Saturday afternoon, winds across the waters surrounding the Big Island will ramp up to tropical storm force in response to the approach of Tropical Storm Hone. A Tropical Storm Warning is in effect for these areas, while a Tropical Storm Watch has been added to the channels and leeward waters of Maui County and Oahu. These Watches may be upgraded to a warning either on this package or the next. TS Hone will also bring occasional heavy rain, low visibility, and the possibility of thunderstorms Saturday afternoon through late Sunday night, especially for the southeastern portion of the coastal waters. Marine interests should monitor updates to the forecast, watches, or warnings over the weekend. Existing small NW swell will slowly decline through early Saturday. Surf along north facing shores will then return to typical summertime flat levels over the weekend through the middle of next week, aside from some trade wind swell wrap. Surf along south facing shores will remain small Saturday, near or slightly below the summertime average. The passing of TC Hone south of the island chain late this weekend may help to elevate surf along south facing shores from early Monday through Tuesday. Short period swell associated with TS Hone will continue building and will maintain hazardous surf for east and southeast facing shores of the Big Island through the weekend. A High Surf Advisory remains in effect . The potential for expansion of the advisory to include east- facing shores of some or all of the smaller islands will be evaluated in subsequent forecast packages. && .FIRE WEATHER... Drier air is expected to filter in across the state on Saturday ahead of Hone. This drier air mass will arrive as winds start to increase, with strong downslope winds expected Saturday. The combination of dry conditions ahead of Hone and the uptick in winds will bring elevated fire weather concerns to leeward portions of the islands. Afternoon relative humidity over leeward areas remain marginal tomorrow around 45-55 percent, however due to strong drying trends ahead of these passing tropical systems a Red Flag Warning remains in effect for Saturday afternoon as the driest air moves over the area. The threat of elevated fire weather concerns decreases late Saturday, as humidity levels recover, and Hone brushes past the southern slopes of the Big Island. && .HFO WATCHES/WARNINGS/ADVISORIES... Wind Advisory from 6 AM Saturday to 6 AM HST Monday for mountain and leeward portions of all islands. Red Flag Warning from 10 AM to 6 PM HST Saturday for leeward portions of all Hawaiian Islands. Flood Watch from Saturday afternoon through Monday evening for Big Island- High Surf Advisory until 6 AM HST Sunday for Big Island Southeast-Big Island East-Big Island North. Tropical Storm Warning for Big Island- Tropical Storm Warning for Alenuihaha Channel-Big Island Windward Waters-Big Island Leeward Waters-Big Island Southeast Waters. Tropical Storm Watch for Kauai Channel-Oahu Leeward Waters-Kaiwi Channel-Maui County Leeward Waters-Maalaea Bay-Pailolo Channel. Small Craft Advisory until 6 PM 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-Maui County Leeward Waters-Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...Bohlin AVIATION...Walsh MARINE...JT Fire Weather...Bohlin