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Displaying AFOS PIL: AFDHFO Product Timestamp: 2022-05-03 06:40 UTC
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587 FXHW60 PHFO 030640 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 840 PM HST Mon May 2 2022 .SYNOPSIS... Breezy trade winds will be rather wet for most of this week, with some locally heavy downpours, and possibly a thunderstorm, through Tuesday. Most of the showers will soak windward communities, but a few showers will occasionally drift to leeward areas. Lighter winds and fewer showers are anticipated by the weekend. && .DISCUSSION... A ridge of high pressure well N of the islands will support breezy to locally strong trade winds this week. A front approaching from the NW by the end of the week will weaken the ridge, leading to lighter trade winds over the weekend. Light to moderate trade winds are then expected to continue into early next week. A closed low aloft just N of the islands has destabilized the island atmosphere, with afternoon soundings indicating a moist and unstable profile. Radar and satellite depict moderate to locally heavy showers persistently forming over windward slopes of Maui and the Big Island, with orographic lift supporting shower development over windward portions of the other islands. Thunderstorms have been especially active over and west of the Big Island since this afternoon, but are currently are on a downtrend. Deep moisture riding up the slopes of the Big Island has led to a mix of wintry precipitation over the summits, and a Winter Weather Advisory has been issued. The slow-moving low aloft will linger near the islands for the next several days, with the coldest 500 mb temps expected over Kauai and Oahu Tuesday and Wednesday. Additional thunderstorms are likely to develop in response, as will a wet trade wind pattern. The short term forecast has been updated to account for this, but expect refinements to the forecast with the next regularly scheduled forecast issuance - mainly to increase windward PoPs, and to increase the areal and temporal coverage of thunderstorms. && .AVIATION... With high pressure persisting north of the islands, trade winds will remain moderate to breezy, and locally strong, through Tuesday. Also, a nearby upper low and trough will continue to destabilize the atmosphere. Showers and isolated thunderstorms, with accompanying MVFR and IFR conditions, are likely until these features depart the area, with the eastern part of the state being most susceptible to heavier precipitation. AIRMET Sierra for mountain obscuration remains in effect for all windward zones. AIRMET Tango for lee turbulence below 090 remains in effect for the entire area. && .MARINE... High pressure north of the state will continue to produce strong trade winds across the area over the next several days. The Small Craft Advisory (SCA) remains in effect for all Hawaiian Coastal Waters through tonight. The combination of strong trades and a late- season northwest swell will keep SCA conditions in place across many areas through the middle of the week. In addition, an upper low over the area has destabilized the local airmass, producing isolated thunderstorms across the area today. This low is expected to linger over the state through the middle of the week. A long-period northwest swell will continue to fill in across exposed north and west waters tonight, then get a reinforcement late Tuesday into Wednesday. With the reinforcement arrival, surf heights could reach low-end advisory levels, then lower gradually through the remainder of the week. A long-period south swell will hold tonight, followed by an even larger south swell arriving Tuesday into Wednesday, peaking Thursday then slowly lowering through rest of the week. Latest near shore buoys are coming in at 5 feet period 17 seconds indicating low- end high surf advisory levels for all south facing shores. A High Surf Advisory has been issued tonight through 6 PM HST Thursday as surf along south facing shores is anticipated to remain elevate as these swells move through the island chain. Trade winds over and upwind of the state will continue to produce above normal, short-period surf along east facing shores through this next week. Surf heights are expected lower during the second half of the week as the trade winds weaken some. && .HFO WATCHES/WARNINGS/ADVISORIES... High Surf Advisory until 6 PM HST Thursday for South facing shores of all islands. Winter Weather Advisory until 6 PM HST Tuesday for Big Island Summits. Small Craft Advisory until 6 AM HST Tuesday for all Hawaiian waters. && $$ DISCUSSION...Birchard AVIATION...Kinel MARINE...VA