Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
768 FXHW60 PHFO 030622 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 822 PM HST Sun Jun 2 2024 .SYNOPSIS... Breezy trades will continue through Tuesday, before easing Wednesday and giving way to sea and land breezes Thursday and Friday. A wet trade wind pattern will continue tonight and early Monday, otherwise trade wind showers will be on the decrease through the middle of the week as a more stable airmass gradually settles overhead. Over the Big Island however, a disturbance aloft may allow for a thunderstorm or two to develop each afternoon through Tuesday. Very dry conditions will overspread the islands Thursday and linger through next weekend, greatly limiting shower activity across the entire state. && .DISCUSSION... Currently at the surface, a 1029 mb high is centered around 925 miles northeast of Honolulu, driving breezy trade winds across the island chain. Infrared satellite imagery shows mostly cloudy conditions for most windward and mauka areas, with partly cloudy skies in most leeward locales. Radar imagery shows scattered to numerous showers affecting windward slopes and coasts, with some of these showers spilling Leeward at times. Main short term focus revolves around trade wind trends and rain chances. The high to the northeast of the islands will weaken as it shifts southeastward during the next few days, with the ridge axis then moving over or very near the western islands Thursday and Friday. Breezy trade winds will continue through Tuesday, before easing into the moderate range for Wednesday. The winds are then expected to become light and variable over the smaller islands Thursday and Friday, allowing for daytime sea breezes and overnight land breezes to be dominant. Meanwhile, light trades will likely hold in the unprotected areas of the Big Island. The surface ridge axis is forecast to shift northward next weekend, which should bring a return and gradual strengthening of the trade winds. As for the remaining weather details, a band of low clouds moving into the islands this evening, will keep rather wet conditions in place over windward slopes and coasts overnight into Monday morning. We should see a typical reduction in trade wind shower coverage by late morning into the afternoon hours, and instability aloft will likely allow for a thunderstorm or two to pop over the Big Island. Fairly typical trade wind weather should then continue Monday night into Tuesday morning, with the trade wind inversion then crashing down to around 5 kft greatly limiting trade wind showers for Tuesday afternoon. Once again, instability aloft will likely allow a thunderstorm or two to pop over the Big Island interior during the afternoon hours. Rather dry trade wind weather will continue Tuesday night through Wednesday night as the trade wind inversion holds around 5 kft, with most leeward areas not seeing any rain. Little change in the trade wind inversion height is expected Thursday through next weekend, greatly limiting shower activity across the entire state. We will likely see a few showers pop over the leeward slopes of the Big Island each afternoon, with very little shower activity elsewhere. A slight increase in windward showers is possible next weekend as the trades gradually return. && .AVIATION... Breezy to strong trades will continue for the next couple of days, as surface high pressure remains north of the area. Low cigs and SHRA will favor windward and mauka areas with periods of MVFR conds possible. VFR should prevail elsewhere. AIRMET Sierra is in effect for windward Big Island as well as N thru E areas of the smaller islands. AIRMET Tango remains in effect for moderate low-level turb S through W of terrain due to the breezy trades. AMD NOT SKED for PMDY as equipment remains unavailable with no time table for return to service. AMD NOT SKED for PHLI as equipment is unavailable. Techs are scheduled for tomorrow. && .MARINE... Strong surface ridge north of the islands will remain stationary through Tuesday leading to strong east northeast trade winds. A Small Craft Advisory (SCA) is posted for the typical windy waters around Maui County and the Big Island through Tuesday. On Wednesday and Thursday, unseasonably strong low pressure rapidly developing north of the area will weaken the high and displace the ridge southward over the islands. Winds will respond by becoming light and variable Thursday and Friday. A conveyor belt set up in the south Pacific has lead to an extended period of elevated surf along south facing shores through potentially the first half of June with numerous swell pulses expected, mainly from the south- southwest. The current south swell has likely peaked and will gradually ease before additional long period energy arrives later in the week. A High Surf Advisory (HSA) is likely to be needed for the largest of the swells, which may not arrive until next weekend. A small, long-period north swell will arrive tonight and Monday, and continue into Tuesday, with the potential for a small follow- up swell later in the week. A small north swell is also possible next weekend. Trade winds will continue to generate short-period wind waves the next couple of days, leading to choppy surf along exposed east facing shores. Wind waves will diminish significantly after Wednesday coinciding with the light winds. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 AM HST Tuesday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...Jelsema AVIATION...Walsh MARINE...Shigesato