Today: Mostly cloudy. Showers likely in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Highs around 77 near the shore to 62 to 67 at 4000 feet. Northeast winds around 10 mph in the morning becoming light. Chance of rain 70 percent.
Tonight: Mostly cloudy early in the evening then becoming mostly clear. Scattered showers and slight chance of thunderstorms early in the evening. Lows around 63 near the shore to around 49 at 4000 feet. Light winds. Chance of rain 50 percent.
Sunday: Mostly sunny early in the morning, then scattered showers in the late morning and afternoon. Highs around 78 near the shore to 62 to 67 at 4000 feet. Light winds. Chance of rain 40 percent.
Kona
Today: Sunny in the morning, then mostly cloudy with scattered showers and slight chance of thunderstorms in the afternoon. Highs 77 to 82 near the shore to around 68 near 5000 feet. Light winds becoming west around 10 mph in the afternoon. Chance of rain 50 percent.
Tonight: Mostly cloudy early in the evening then becoming mostly clear. Scattered showers and slight chance of thunderstorms early in the evening. Lows 63 to 69 near the shore to around 50 near 5000 feet. North winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.
ARTICLE CONTINUES BELOW AD
ARTICLE CONTINUES BELOW AD
Sunday: Sunny early in the morning, then mostly cloudy with scattered showers in the late morning and afternoon. Highs 77 to 82 near the shore to around 68 near 5000 feet. North winds around 10 mph. Chance of rain 40 percent.
Waimea
Today: Mostly cloudy. Showers likely in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Highs 61 to 77. Light winds. Chance of rain 70 percent.
Tonight: Partly cloudy. Scattered showers and slight chance of thunderstorms early in the evening. Lows around 62 near the shore to 49 to 57 near 3000 feet. Southwest winds up to 10 mph. Chance of rain 50 percent.
Sunday: Mostly sunny. Scattered showers in the late morning and afternoon. Highs around 77 near the shore to 68 to 75 near 3000 feet. Southwest winds around 10 mph. Chance of rain 40 percent.
Kohala
Today: Mostly cloudy. Showers likely in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Highs 61 to 77. Light winds. Chance of rain 70 percent.
ARTICLE CONTINUES BELOW AD
Tonight: Partly cloudy. Scattered showers and slight chance of thunderstorms early in the evening. Lows around 62 near the shore to 49 to 57 near 3000 feet. Southwest winds up to 10 mph. Chance of rain 50 percent.
Sunday: Mostly sunny. Scattered showers in the late morning and afternoon. Highs around 77 near the shore to 68 to 75 near 3000 feet. Southwest winds around 10 mph. Chance of rain 40 percent.
South Big Island
Today: Sunny in the morning, then mostly cloudy with scattered showers and slight chance of thunderstorms in the afternoon. Highs around 80 near the shore to around 69 near 5000 feet. Southeast winds around 10 mph. Chance of rain 50 percent.
Tonight: Mostly cloudy early in the evening then becoming mostly clear. Scattered showers and slight chance of thunderstorms early in the evening. Lows around 65 near the shore to around 49 near 5000 feet. Light winds. Chance of rain 50 percent.
Sunday: Sunny early in the morning, then mostly cloudy with scattered showers in the late morning and afternoon. Highs around 80 near the shore to around 69 near 5000 feet. North winds around 10 mph. Chance of rain 40 percent.
Puna
ARTICLE CONTINUES BELOW AD
Today: Mostly cloudy. Showers likely in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Highs around 77 near the shore to 62 to 67 at 4000 feet. Northeast winds around 10 mph in the morning becoming light. Chance of rain 70 percent.
Tonight: Mostly cloudy early in the evening then becoming mostly clear. Scattered showers and slight chance of thunderstorms early in the evening. Lows around 63 near the shore to around 49 at 4000 feet. Light winds. Chance of rain 50 percent.
Sunday: Mostly sunny early in the morning, then scattered showers in the late morning and afternoon. Highs around 78 near the shore to 62 to 67 at 4000 feet. Light winds. Chance of rain 40 percent.
Waikoloa
Today: Sunny with scattered showers in the morning, then partly sunny with scattered showers and slight chance of thunderstorms in the afternoon. Highs around 79 near the shore to 63 to 70 above 4000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.
Tonight: Mostly cloudy early in the evening then becoming mostly clear. Scattered showers and slight chance of thunderstorms early in the evening. Lows around 67 near the shore to 45 to 53 above 4000 feet. South winds up to 10 mph in the evening becoming light. Chance of rain 50 percent.
Sunday: Sunny early in the morning, then partly sunny with scattered showers in the late morning and afternoon. Highs around 79 near the shore to 63 to 70 above 4000 feet. South winds around 10 mph. Chance of rain 40 percent.
Detailed Forecast
Synopsis
Diminishing trade winds will bring a few windward showers this morning, with winds becoming light and variable by the afternoon, which may allow a few showers to develop over leeward areas. Mostly clear skies are expected tonight and Sunday morning, with some upslope and interior clouds and showers Sunday afternoon. A couple of cold fronts will move through the islands from late Sunday into Thursday, bringing occasionally gusty southwest to west winds and increased rain, especially for leeward areas. Cool and dry weather, with lighter winds, is expected for the second half of the week.
Discussion
Light to moderate trade winds are hanging on by a thread this morning, supported by a surface high to the distant NNE. The island atmosphere remains somewhat unstable due to a complex low aloft that is near/over the E end of the island chain. Overnight soundings show a moist and unstable atmosphere persists, with no subsidence inversion, and PWAT near 1.5″. Despite this, the overnight radar trend indicates a steadily decreasing number of showers – moving over windward portions of the islands. While rain cores are not as intense as they have been in recent days, a few rain gages did receive briefly heavy rain overnight.
Trade winds will continue to diminish today (and not return for at least several days) as the high to the NNE finally loses its grip on island weather. In its stead, a large, complex and relatively slow- moving area of low pressure will develop and prevail NW and N of the islands for the next several days.
The trade winds will deliver a few showery low clouds to windward areas this morning as winds trend even lighter, but the wet and windy weather of the past several days is all but gone. Weakening winds will likely allow convergent sea breezes to develop over leeward areas this afternoon, especially on the Big Island. With the island atmosphere remaining somewhat unstable, a few of the resultant showers may become briefly heavy, with a chance of thunderstorms over the Big Island. Light and variable winds will develop by tonight and continue Sunday as a cold front now about 800 miles NW of Kauai moves closer. The low aloft will continue to gradually weaken and move E through Monday.
Land breezes will bring locally stable and mostly clear conditions tonight. Little change is expected for Sunday, except that interior showers will probably be of lower intensity as compared to today. Increasing SW winds Sunday will bring some clouds and showers to leeward areas, especially on Kauai and Oahu as the front nears Kauai.
As the surface ridge moves well SE of the islands and deep low pressure prevails to the N, SW to W winds will prevail from Monday through Wednesday night, at times locally gusty (especially over windward areas), with forecast details hinging on the strength and proximity of the passing lows. Latest guidance indicates that the strongest low will pass N of the islands on Wednesday/Thursday, potentially bringing strong and impactful W winds. The unusual wind direction and well-soaked soils increases the potential for impacts in the form of falling trees/landslides.
The first cold front will move over Kauai from the NW Sunday night, potentially reaching Oahu/Maui County Monday/Monday night before stalling and weakening. A second front (associated with the strong low passing to the N) will closely follow, moving over Kauai Tuesday night, and moving across the entire chain through early Thursday. The atmosphere will be relatively stable as the fronts pass, and although there will likely be a few briefly heavy showers, widespread heavy rainfall is not anticipated, with rainfall focused over leeward areas.
After the passage of the second front, high pressure building NW of the islands looks to deliver a dry, cool and stable air mass with NW to N winds on Thursday. Light winds appear likely to continue into next weekend, with limited showers as the relatively cool air mass is slow to modify.
Aviation
Moderate trades this morning will continue to slowly ease through the day, with localized sea breezes developing in some of the more sheltered areas this afternoon. Low clouds and showers will favor windward and mauka areas this morning, with a stray shower possibly reaching leeward areas at times. The combination of daytime heating and sea breeze development will allow for scattered showers over interior and leeward areas this afternoon. A slight chance of thunderstorms will remain in the forecast for the Big Island this afternoon.
AIRMET Sierra remains in effect for mountain obscuration across windward sections of Kauai and the Big Island. Conditions should improve later this morning.
AIRMET Tango remains in effect for moderate low level turbulence over and downwind of the terrain of all islands. This AIRMET will likely be cancelled with the 16z AIRMET package. AIRMET Tango also remains in effect for moderate upper level turbulence over the entire state. This AIRMET will likely be required through the day. See also SIGMETS Sierra and Tango series for severe turbulence over the islands.
Marine
The long duration trade wind event will finally be tapering off through the day and ending Sunday as early week light to gentle winds transition more southwest. The impetus for these recently strong trades, or tight northeast-to-southwest pressure gradient over and upstream of the state from a large area of high pressure far north northeast of the islands, will weaken in response to the high moving further away to the east as a cold front approaches the region from the west northwest. The Small Craft Advisory has been allowed to expire for both winds and elevated seas. As the front nears the western waters late tonight, areawide veering southerlies will become light and variable Sunday. As the front lifts northeast of the offshore waters Monday, southwest winds will strengthen to light to moderate. A potentially deepening surface low northwest of the islands will be moving north of the island chain through the middle of next week. The low's associated front will be passing across the waters Wednesday. Post-frontal west to southwest winds may reach moderate to locally strong magnitudes across the majority of the marine zones from Tuesday night through Wednesday night.
East-facing shore surf is steadily declining in direct response to easing trades. This east chop will continue to lower the next few days. A recent small northwest swell is already fading, thus only small surf is expected through Tuesday along north and west-facing shores. An large, medium period northwest swell emanating along the western periphery of a surface low northwest to north of the offshore waters is forecast to arrive through the day on Wednesday. If this swell materializes, it will likely produce warning level surf along all north and west-facing shores of the state. Very small, medium period background south swell, with a small bump expected Sunday along the eastern end of the state, will generally maintain just knee high surf along many south-facing shores. Choppy, more rough surf conditions could develop across the southern nearshore waters during the middle of next week if west to southwest winds achieve locally fresh to strong magnitudes in relation to a frontal passage.
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