Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
387 FXHW60 PHFO 242000 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 1000 AM HST Tue Sep 24 2024 .SYNOPSIS... Moderate to locally breezy trade winds will continue for the next couple of days, with lighter east to southeast winds expected over the weekend. Limited rainfall is expected, with brief showers favoring windward areas, with some afternoon showers over the Big Island`s leeward slopes. && .DISCUSSION... A surface ridge along 35N will support moderate to locally breezy trade winds for the next couple of days. By the end of the week, developing low pressure will force the ridge southward toward the islands, leading to lighter E to SE winds, especially for Kauai and Oahu. The fast-moving low will move far NE of the area late in the weekend, and the ridge will rebound northward, leading to a return of moderate to breezy trade winds by Monday. A mid-level ridge will build over the islands from the E the next couple of days, then remain in place through the weekend. End result will be a relatively dry weather pattern, with brief showers favoring windward areas, especially night and morning. && .AVIATION... Moderate to locally breezy trade winds will continue through the week. The air mass will become increasingly dry and stable over the next few days. Infrequent bands of light trade wind showers will impact mainly windward slopes and coasts. Scattered light showers are possible over the upper elevations of the Big Island in the late afternoon and evening hours. Expect VFR conditions to prevail all areas. No AIRMETs are currently in effect and none are anticipated at this time. && .MARINE... The weak trough that passed north of the state yesterday is now west of the state and moderate to locally strong trade winds have returned. A Small Craft Advisory remains in effect for the typical windy waters around Maui County and the Big Island through Wednesday. Trade winds should hold around the moderate to locally strong speeds through Friday then gradually decline over the weekend as the high weakens north of the state. For the offshore waters, the weak trough will bring a slight chance of thunderstorms over the far western waters through today. A moderate long period northwest swell (320 to 330 degrees) will steadily fill in throughout the day today and should peak tonight into Wednesday morning then gradually decline the rest of the work week. Buoy 51001 and 51101 northwest of Kauai showed a peak swell height of around 6 to 7 feet 16 seconds earlier this morning. This should translate to surf peaking just below advisory thresholds tonight for north facing shores of Kauai and Oahu. A smaller north- northwest swell should provide a boost this weekend. Surf along south facing shores should see a series of small long- period southwest pulses through the weekend due to a series of storms near the Tasman Sea last week. The first pulse filled in overnight and will likely peak today. Another long-period southwest swell is expected Friday into the weekend. Additionally, a fetch of strong southwest winds near 10N170W yesterday should bring an increase of short-period energy from the southwest Wednesday into Thursday. East facing shores should remain small through much of the week due to the lack of strong trades locally or upstream of the state. && .FIRE WEATHER... KBDI values are in excess of 600, and minimum RH values near 45% are expected for a period this afternoon, but sustained winds will likely remain below the 20 mph criteria (for a Red Flag Warning) at PHNL. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST Wednesday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION/FIRE WEATHER...Birchard AVIATION...Bedal MARINE...Kino