Today: Mostly cloudy. Scattered showers and slight chance of thunderstorms in the morning, then showers likely and slight chance of thunderstorms in the afternoon. Locally heavy rainfall possible in the afternoon. Highs around 80 near the shore to 64 to 69 at 4000 feet. Southeast winds up to 10 mph. Chance of rain 70 percent.
Tonight: Mostly cloudy with scattered showers and slight chance of thunderstorms. Lows around 65 near the shore to around 51 at 4000 feet. Southwest winds up to 10 mph. Chance of rain 50 percent.
Monday: Mostly cloudy. Scattered showers in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Highs around 80 near the shore to 64 to 69 at 4000 feet. Southwest winds up to 10 mph shifting to the southeast in the afternoon. Chance of rain 50 percent.
Kona
Today: Partly sunny. Slight chance of thunderstorms in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Highs 79 to 84 near the shore to around 70 near 5000 feet. North winds up to 10 mph shifting to the west in the afternoon. Chance of rain 50 percent.
Tonight: Mostly cloudy with scattered showers and slight chance of thunderstorms. Lows 65 to 72 near the shore to around 52 near 5000 feet. Light winds. Chance of rain 50 percent.
ARTICLE CONTINUES BELOW AD
ARTICLE CONTINUES BELOW AD
Monday: Mostly cloudy. Isolated showers in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Highs 79 to 84 near the shore to around 70 near 5000 feet. Light winds. Chance of rain 40 percent.
Waimea
Today: Mostly cloudy. Showers likely and slight chance of thunderstorms in the afternoon. Locally heavy rainfall possible in the afternoon. Highs around 79 near the shore to 70 to 77 near 3000 feet. Light winds. Chance of rain 70 percent.
Tonight: Mostly cloudy with scattered showers and slight chance of thunderstorms. Lows around 64 near the shore to 50 to 58 near 3000 feet. Light winds. Chance of rain 40 percent.
Monday: Mostly cloudy. Isolated showers in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Highs around 79 near the shore to 70 to 77 near 3000 feet. Light winds. Chance of rain 50 percent.
Kohala
Today: Mostly cloudy. Showers likely and slight chance of thunderstorms in the afternoon. Locally heavy rainfall possible in the afternoon. Highs around 79 near the shore to 70 to 77 near 3000 feet. Light winds. Chance of rain 70 percent.
ARTICLE CONTINUES BELOW AD
Tonight: Mostly cloudy with scattered showers and slight chance of thunderstorms. Lows around 64 near the shore to 50 to 58 near 3000 feet. Light winds. Chance of rain 40 percent.
Monday: Mostly cloudy. Isolated showers in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Highs around 79 near the shore to 70 to 77 near 3000 feet. Light winds. Chance of rain 50 percent.
South Big Island
Today: Mostly sunny with slight chance of thunderstorms and isolated showers in the morning, then mostly cloudy with scattered showers and slight chance of thunderstorms in the afternoon. Highs around 82 near the shore to around 71 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.
Tonight: Mostly cloudy with scattered showers and slight chance of thunderstorms. Lows around 67 near the shore to around 51 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.
Monday: Partly sunny. Isolated showers in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Highs around 82 near the shore to around 71 near 5000 feet. Southeast winds up to 10 mph. Chance of rain 40 percent.
Puna
ARTICLE CONTINUES BELOW AD
Today: Mostly cloudy. Scattered showers and slight chance of thunderstorms in the morning, then showers likely and slight chance of thunderstorms in the afternoon. Locally heavy rainfall possible in the afternoon. Highs around 80 near the shore to 64 to 69 at 4000 feet. Southeast winds up to 10 mph. Chance of rain 70 percent.
Tonight: Mostly cloudy with scattered showers and slight chance of thunderstorms. Lows around 65 near the shore to around 51 at 4000 feet. Southwest winds up to 10 mph. Chance of rain 50 percent.
Monday: Mostly cloudy. Scattered showers in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Highs around 80 near the shore to 64 to 69 at 4000 feet. Southwest winds up to 10 mph shifting to the southeast in the afternoon. Chance of rain 50 percent.
Waikoloa
Today: Mostly sunny in the morning, then partly sunny with scattered showers and slight chance of thunderstorms in the afternoon. Highs around 81 near the shore to 65 to 72 above 4000 feet. East winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 50 percent.
Tonight: Mostly cloudy with scattered showers and slight chance of thunderstorms. Lows 67 to 72 near the shore to 47 to 55 above 4000 feet. Light winds. Chance of rain 40 percent.
Monday: Partly sunny. Isolated showers in the morning, then scattered showers and slight chance of thunderstorms in the afternoon. Highs around 81 near the shore to 65 to 72 above 4000 feet. Southeast winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 50 percent.
Detailed Forecast
Synopsis
A low northwest of the islands will move away from the area, but a moist and unstable southerly wind flow will remain in place through Monday. There will be a chance of thunderstorms statewide through tonight, but heavy rainfall will be most likely over Oahu and Kauai County. A gradual drying trend is expected to begin Monday, with winds becoming light. The light winds will combine with a stable island atmosphere by midweek, with much fewer showers expected.
Discussion
Currently at the surface, a surface low is located to the distant northwest, with a weakening cold front extending southward from the low to a location around 300 miles west of Kauai. Meanwhile, a 1025 mb high is centered around 2000 miles east-northeast of the Big Island. Closer to home, a north to south oriented trough of low pressure is located around 50 miles west of the Garden Isle, with widespread convection along and to the east of this feature. The boundary layer wind fields are generally south and southeast at moderate speeds, creating a confluent flow over the island chain. Infrared satellite imagery shows mostly cloudy conditions over Kauai and Oahu, with partly cloudy skies over the other islands. Radar imagery shows widespread showers and a few thunderstorms over Kauai and Oahu, with isolated showers over the remainder of the state. Main short term concern revolves around rainfall trends during the next few days.
High pressure will remain centered to the distant east-northeast through early next week, while the weakening front several hundred miles west of Kauai dissipates. Moderate south to southeasterly winds are expected today, before easing to light levels tonight through Monday night. A new cold front approaching from the northwest will shift winds around to the south and southwest on Tuesday and Tuesday night, with winds becoming light and variable on Wednesday as the front stalls out and dissipates a few hundred miles northwest of Kauai. Light trades may briefly return Wednesday night and Thursday as a weak and fast moving high slides by to the north of the state, but will likely be overpowered in many areas by overnight land breezes and daytime sea breezes, particularly in leeward areas. Winds appear to remain light Thursday night, but could pick up slightly out of the west and southwest Friday as a weakening front approaches from the northwest. Overall, light winds are expected through the vast majority of the next 7 days.
As for the remaining weather details, confluent southerly flow and troughing aloft will keep unsettled conditions in place today and tonight. Numerous showers and a few thunderstorms are expected today over Kauai and Oahu, and as a result the Flood Watch has been extended through 6 PM this evening. Scattered to numerous showers and a thunderstorm or two are also expected over Maui County and the Big Island this afternoon, with locally heavy rainfall possible here as well. The flood threat over Maui County and the Big Island doesn't appear as great, so will leave these areas out of the Flood Watch.
The airmass will begin to slowly dry and stabilize during the first half of the week, as the deepest moisture lifts out to the northeast along with troughing aloft. Precipitable water values fall below 1.5 inches Monday morning and drop to around 1.2 inches or less by late Wednesday. The airmass appears to dry out further Thursday and Friday with precipitable water values dropping below 1 inch in many areas. As a result, we should see shower coverage and intensity gradually diminish through the week, with mostly dry conditions expected across the majority of the state for Thursday and Friday. A predominantly land and sea breeze pattern is expected for much of next week, which favors interior showers each afternoon and a few showers near the coast each night.
Aviation
An upper level low just west of Kauai will keep periods of wet weather with isolated thunderstorms in the forecast through this evening. The highest chances for MVFR/IFR conditions will remain over the islands of Kauai, Oahu and Molokai. Enough mid level clouds will linger over Kauai and Oahu to produce light icing conditions.
AIRMET SIERRA remains in effect for tempo mountain obscurations over Kauai and Oahu.
AIRMET Tango remains in effect for tempo moderate turbulence for all islands between FL200 and FL300.
Marine
Light to moderate SE to S winds today will weaken on Monday as a surface ridge builds over the area from the ENE, with light and variable winds expected for most of next week as the ridge remains close to the islands. A brief and short-lived period of trade winds is possible around midweek. A mid-level ridge building over the area will support a stable island atmosphere, with much fewer showers by the middle of the week.
Several WNW to NW swells are expected in the coming week. The first relatively small swell will be peaking today before diminishing Monday. The second swell is expected to build Tuesday into Wednesday, with resultant surf heights along exposed N and W facing shores easily reaching High Surf Advisory criteria as the long-period (open ocean) swell peaks near 10 feet into Thursday. The third swell could bring even larger surf next weekend as an extended fetch develops to the NW of the islands, with even more large surf potential in the extended forecast. A strong, slow- moving low in the Bering Sea will also send a long- to medium- period N swell through the area from Tuesday into Thursday. While winds will remain below Small Craft Advisory (SCA) criteria through the period, combined seas greater than 10 feet will likely require a SCA Wednesday and Thursday, and potentially again next weekend.
HFO Watches/Warnings/Advisories
Flood Watch through 6 PM this evening of Niihau, Kauai and Oahu.
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