West Side

Rest Of Tonight: Mostly cloudy early in the evening then becoming partly cloudy. Isolated showers early in the evening, then scattered showers in the late evening and overnight. Lows 64 to 71. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Sunday: Mostly sunny with scattered showers early in the morning, then mostly cloudy with isolated showers in the late morning and afternoon. Highs 75 to 81. Southeast winds up to 15 mph. Chance of rain 40 percent.

Sunday Night: Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows 65 to 71. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

South Side

Rest Of Tonight: Mostly cloudy early in the evening then becoming partly cloudy. Isolated showers in the late evening and overnight. Lows 62 to 73. Light winds. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers early in the morning, then mostly cloudy in the late morning and afternoon. Highs around 83. Northwest winds up to 10 mph. Chance of rain 20 percent.

Sunday Night: Mostly cloudy in the evening then becoming mostly clear. Lows 63 to 74. Northwest winds up to 10 mph in the evening becoming light.

North Shore

Rest Of Tonight: Mostly cloudy with scattered showers. Lows around 66 near the shore to around 49 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Sunday: Mostly cloudy with scattered showers. Highs 75 to 80 near the shore to around 64 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Sunday Night: Scattered showers in the evening, then occasional showers after midnight. Lows around 67 near the shore to around 50 near 5000 feet. Southeast winds up to 15 mph. Chance of rain near 100 percent.

Central Maui

Rest Of Tonight: Mostly cloudy with isolated showers early in the evening, then partly cloudy with scattered showers in the late evening and overnight. Lows around 65. Southeast winds up to 15 mph shifting to the northeast after midnight. Chance of rain 40 percent.

Sunday: Mostly sunny early in the morning then becoming mostly cloudy. Breezy. Scattered showers early in the morning, then isolated showers in the late morning and afternoon. Highs 79 to 84. East winds up to 20 mph. Chance of rain 40 percent.

Sunday Night: Mostly cloudy in the evening then becoming mostly clear. Isolated showers. Lows 63 to 68. East winds up to 15 mph. Chance of rain 20 percent.

Upcountry

Rest Of Tonight: Mostly cloudy. Isolated showers early in the evening, then scattered showers in the late evening and overnight. Lows around 44 at the visitor center to around 38 at the summit. Southeast winds up to 15 mph. Chance of rain 50 percent.

Sunday: Partly sunny with scattered showers early in the morning, then cloudy with isolated showers in the late morning and afternoon. Highs 54 to 65. East winds up to 15 mph. Chance of rain 50 percent.

Sunday Night: Mostly cloudy with isolated showers in the evening, then partly cloudy with scattered showers after midnight. Lows around 45 at the visitor center to around 41 at the summit. Southeast winds up to 15 mph. Chance of rain 50 percent.

East Maui

Rest Of Tonight: Mostly cloudy with scattered showers. Lows around 66 near the shore to around 49 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.

Sunday: Mostly cloudy with scattered showers. Highs 75 to 80 near the shore to around 64 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Sunday Night: Scattered showers in the evening, then occasional showers after midnight. Lows around 67 near the shore to around 50 near 5000 feet. Southeast winds up to 15 mph. Chance of rain near 100 percent.

Lanai City

Rest Of Tonight: Mostly cloudy early in the evening then becoming partly cloudy. Lows 60 to 65. Light winds.

Sunday: Mostly sunny early in the morning then becoming mostly cloudy. Highs 71 to 78. Light winds.

Sunday Night: Mostly cloudy in the evening then becoming mostly clear. Lows around 63. Light winds.

Kaunakakai

Rest Of Tonight: Mostly cloudy with isolated showers. Lows 54 to 71. East winds up to 10 mph. Chance of rain 20 percent.

Sunday: Mostly cloudy with isolated showers. Highs 67 to 83. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Sunday Night: Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows 55 to 71. East winds 10 to 15 mph decreasing to up to 10 mph after midnight. Chance of rain 20 percent.

Detailed Forecast

Synopsis

The potential for locally heavy showers and a few thunderstorms will persist through Monday as an upper-level disturbance remains positioned west of the state. While most of the rainfall will favor windward and mauka locations due to light to moderate east- southeast winds, afternoon sea breezes will support showers developing over interior and leeward areas. A return to moderate to breezy easterly trade winds is expected from late Tuesday through midweek, with showers primarily favoring windward and mauka locations through the rest of the week.

Discussion

Short-term model guidance remains in good agreement, indicating that the moist and unstable pattern will persist through Monday as a deep area of low pressure lingers west of the state. Similar to today, periods of locally heavy rainfall are expected, particularly over the western end of the state, where instability is greatest. Showers will primarily affect windward and mauka areas overnight and into the morning hours, then shift over leeward locations each afternoon as sea breezes develop with the prevailing light to moderate east-southeast flow. Although the deepest moisture remains positioned to the north and west of the islands, a few thunderstorms cannot be ruled out given the instability, especially over the western end of the state during peak daytime heating.
By midweek, a return to moderate to breezy trade winds is expected as high pressure builds to the north and the surface low west of the state moves farther away. Meanwhile, the upper low will weaken into an open trough as it drifts eastward over the region from Tuesday through Thursday. This pattern will shift showers back to the typical windward and mauka locations statewide, especially as pockets of low-level moisture move through. More stable conditions are anticipated later in the week as upper heights rise and the weakening upper trough exits east of the state.

Aviation

Light to moderate ESE winds with localized land/sea breezes can be expected this weekend as a surface low and upper trough linger to the west of the islands. In addition, expect SHRA over windward and mauka areas, then over interior and leeward sections during the afternoons where sea breezes form. It is possible due to enough instability for a few TSRA but these will be isolated in nature and mostly over water. While MVFR conds can be expected in any SHRA, VFR should generally prevail.
AIRMET Sierra is in effect for mtn obsc for all of Kauai and Oahu, as well as N thru SE sections of the rest of the islands.

Marine

Light to moderate east-southeast winds will continue across the state as an area of low pressure meanders northwest of the state. Isolated thunderstorms will be possible through Sunday, mainly for the western waters, due to the proximity of the low. Near term and long term winds have been updated since this afternoon and now shows east southeast winds strengthening to moderate to locally fresh over the eastern half of the chain Sunday, while the western half remains in a light to moderate east-southeast flow. As the low weakens and drifts westward early next week and a couple of strong high pressure systems will pass north of the state. Winds will gradually back to a more typical easterly direction and increase to moderate to locally fresh speeds statewide by Tuesday night then continue to increase in strengthen becoming locally strong during the second half of next week.
A moderate, west-northwest (300-320) swell will continue to trend down through the rest of the weekend. A small to moderate, medium-period north-northwest swell (340-350) may arrive Sunday night, peak Monday then slowly fade into Wednesday. In the long range, a series of small, long- period northwest (320-330) swells look to keep surf from going flat Tuesday through much of next week.
Expect choppy surf along east facing shores through early next week. As winds strengthen by midweek, expect east shore surf to pick back up a notch or two through the rest of next week. A tiny bump in south shore surf will fade Sunday. A series of small, long period south swell will keep surf from going flat starting late Monday into Tuesday then persisting much of next week.

HFO Watches/Warnings/Advisories

High Wind Warning until 6 AM HST Sunday for Big Island Summits.

Data Courtesy of NOAA.gov