Today: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 77 to 82 near the shore to around 63 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.
Tonight: Cloudy. Numerous showers in the evening, then showers after midnight. Lows 63 to 69 near the shore to around 54 at 4000 feet. East winds up to 15 mph. Chance of rain 90 percent.
Wednesday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 80 near the shore to around 62 at 4000 feet. North winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 70 percent.
Kona
Today: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 82 to 87 near the shore to around 66 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.
Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 72 near the shore to 47 to 52 near 5000 feet. Light winds. Chance of rain 40 percent.
ARTICLE CONTINUES BELOW AD
ARTICLE CONTINUES BELOW AD
Wednesday: Partly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 84 near the shore to around 65 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.
Waimea
Today: Breezy. Partly sunny with scattered showers. Highs around 77 near the shore to 65 to 75 near 3000 feet. East winds up to 25 mph. Chance of rain 50 percent.
Tonight: Windy. Mostly cloudy with scattered showers. Lows 62 to 70 near the shore to 54 to 61 near 3000 feet. East winds up to 30 mph. Chance of rain 50 percent.
Wednesday: Windy. Partly sunny with scattered showers. Highs around 76 near the shore to 64 to 74 near 3000 feet. East winds up to 30 mph with gusts to 50 mph. Chance of rain 50 percent.
Kohala
Today: Breezy. Partly sunny with scattered showers. Highs around 77 near the shore to 65 to 75 near 3000 feet. East winds up to 25 mph. Chance of rain 50 percent.
ARTICLE CONTINUES BELOW AD
Tonight: Windy. Mostly cloudy with scattered showers. Lows 62 to 70 near the shore to 54 to 61 near 3000 feet. East winds up to 30 mph. Chance of rain 50 percent.
Wednesday: Windy. Partly sunny with scattered showers. Highs around 76 near the shore to 64 to 74 near 3000 feet. East winds up to 30 mph with gusts to 50 mph. Chance of rain 50 percent.
South Big Island
Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 82 near the shore to around 65 near 5000 feet. East winds 10 to 25 mph. Chance of rain 20 percent.
Tonight: Partly cloudy. Windy. Isolated showers in the evening. Lows around 72 near the shore to around 51 near 5000 feet. East winds 10 to 30 mph with gusts to 50 mph. Chance of rain 20 percent.
Wednesday: Partly sunny. Very windy. Scattered showers in the afternoon. Highs around 82 near the shore to around 65 near 5000 feet. East winds 10 to 40 mph. Chance of rain 40 percent.
Puna
ARTICLE CONTINUES BELOW AD
Today: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 77 to 82 near the shore to around 63 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.
Tonight: Cloudy. Numerous showers in the evening, then showers after midnight. Lows 63 to 69 near the shore to around 54 at 4000 feet. East winds up to 15 mph. Chance of rain 90 percent.
Wednesday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 75 to 80 near the shore to around 62 at 4000 feet. North winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 70 percent.
Waikoloa
Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 80 to 87 near the shore to 64 to 71 above 4000 feet. Northeast winds up to 25 mph. Chance of rain 20 percent.
Tonight: Partly cloudy. Windy. Isolated showers after midnight. Lows around 73 near the shore to 50 to 55 above 4000 feet. East winds up to 30 mph. Chance of rain 20 percent.
Wednesday: Partly sunny. Breezy. Isolated showers in the afternoon. Highs 80 to 87 near the shore to 63 to 69 above 4000 feet. Northeast winds up to 25 mph with gusts to 50 mph. Chance of rain 20 percent.
Detailed Forecast
Synopsis
A strong high pressure system will build in north of the Hawaiian Islands this week. Easterly trade winds will gradually strengthen over the next few days, with windy trades and stronger gusts forecast to blow from Wednesday into Friday. Upstream moisture riding in on the trade winds will produce periods of showers favoring windward mountain slopes, some of these stronger showers will spread into drier leeward areas. These strong trade winds will slowly ease into moderate to breezy thresholds from Saturday to Sunday as the high center north of the state weakens.
Discussion
The weather picture this morning remains fairly similar to last night with trough, dissipated front, northwest of the state and a building high pressure system farther north of the trough boundary. The long unstable cloud band currently moving through the state will likely drift through all islands later this morning with a brief decrease in shower trends forecast for the afternoon time period. An upper level low continues to develop roughly 900 miles west of Kauai. High cirrus clouds associated with the eastern edge of this upper low will fill in over the island chain today.
Wet trade wind weather will continue through much of the week with higher shower coverage in the overnight to early morning hours. A strong high pressure system will slowly build in far north of the islands over the next few days with a very strong central pressure forecast at around 1050 mb. Trade winds will steadily increase today and tonight, and then peak at windy levels from Wednesday to Thursday. Wind advisories were issued this morning starting later this evening for the windier zones of each island. Maui and Big Island summits wind speeds will be lighter and remain below wind advisory thresholds during this wind event.
The developing upper level cutoff low west of the state will tend to add some instability into the mix over the western islands. The impacts of this low on island weather will depend upon how close the upper level low center and cold pool gets to Kauai and Oahu. For now we are keeping fairly tame wet trade winds in the forecast. However, if this cutoff low moves closer to the Hawaiian Islands, then we could see a brief period of heavy showers and thunderstorms mainly over Kauai, and possibly as far east as Oahu. Stay tuned.
Trade winds will slowly ease over the weekend with breezy conditions, and mostly windward showers, favoring the overnight to early morning hours.
Aviation
Breezy to locally windy easterly trade winds will persist, with clouds and showers favoring windward slopes and coasts. Expect periods with MVFR CIGs/VSBYs in showers, particularly overnight through the early morning hours. Some showers will spill over into leeward areas of the smaller islands periodically.
AIRMET Sierra for mountain obscuration remains in effect for N through E sections for Maui and the Big Island.
AIRMET Tango for moderate low-level turbulence over and southwest through northwest of mountains remains in effect for all islands.
Marine
A 1044 mb surface high far N of the islands will drift E over the next day or two, peaking near 1052 mb as it passes N of the islands tomorrow, leading to increasingly strong E trade winds. The high will drift S as it gradually weakens from Thursday through Saturday. Based on an overnight ASCAT pass, trade winds are already on the increase. A Small Craft Advisory is in effect for all waters, and will be upgraded to a Gale Warning for the windier zones tonight. The Marine Weather Message (MWWHFO) contains the details. Winds will ease slightly Friday and Saturday, but will remain strong to near gale-force.
A nearby fetch of N winds has generated a short-period (~10 seconds) N swell that will gradually build today and peak Wednesday (near 5 feet) before diminishing. Peak surf heights will remain below High Surf Advisory heights. The strengthening trade winds will drive increasing short-period wind waves toward the islands from the E over the next couple of days, with E shore peak surf heights likely exceeding 10 feet (thus requiring a High Surf Advisory) from Wednesday into Friday. Anomalously strong low pressure in the distant SE Pacific has an associated fetch that may deliver a small, medium-period SSE swell by the weekend.
Fire weather
Long-term conditions over leeward areas are drier than normal for this time of year. Though the Keetch-Byram Drought Index measured in Honolulu will remain well below the critical 600 mark this week, the strong and gusty trade winds will elevate the fire danger over the drier leeward areas over the next several days.
HFO Watches/Warnings/Advisories
Wind Advisory from 6 PM this evening to 6 PM HST Thursday windier areas across the state.
Small Craft Advisory until 6 PM HST Thursday 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, Big Island Windward Waters.
Small Craft Advisory until 6 PM HST this evening for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Gale Warning from 6 PM this evening to 6 PM HST Thursday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
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