Hilo

Tonight: Mostly cloudy with numerous showers. Lows 65 to 73 near the shore to around 58 at 4000 feet. North winds up to 15 mph. Chance of rain 70 percent.

Monday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 88 near the shore to 66 to 71 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Monday Night: Mostly cloudy with scattered showers. Lows 64 to 72 near the shore to around 57 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Kona

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 75 near the shore to 51 to 56 near 5000 feet. Light winds. Chance of rain 20 percent.

Monday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 84 to 90 near the shore to around 69 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Monday Night: Partly cloudy. Isolated showers in the evening. Lows around 75 near the shore to 50 to 56 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 65 to 74 near the shore to 57 to 64 near 3000 feet. East winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain 50 percent.

Monday: Breezy. Partly sunny with scattered showers. Highs 66 to 87. East winds up to 20 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy with scattered showers. Lows 65 to 73 near the shore to 56 to 63 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Kohala

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 65 to 74 near the shore to 57 to 64 near 3000 feet. East winds 10 to 20 mph decreasing to up to 20 mph after midnight. Chance of rain 50 percent.

Monday: Breezy. Partly sunny with scattered showers. Highs 66 to 87. East winds up to 20 mph. Chance of rain 50 percent.

Monday Night: Mostly cloudy with scattered showers. Lows 65 to 73 near the shore to 56 to 63 near 3000 feet. East winds up to 15 mph. Chance of rain 50 percent.

South Big Island

Tonight: Partly cloudy. Breezy. Isolated showers in the evening. Lows around 75 near the shore to around 54 near 5000 feet. Northeast winds up to 20 mph. Chance of rain 20 percent.

Monday: Mostly sunny. Breezy. Scattered showers in the afternoon. Highs around 87 near the shore to around 69 near 5000 feet. East winds up to 25 mph. Chance of rain 50 percent.

Monday Night: Mostly clear. Lows around 75 near the shore to around 54 near 5000 feet. East winds 10 to 15 mph.

Puna

Tonight: Mostly cloudy with numerous showers. Lows 65 to 73 near the shore to around 58 at 4000 feet. North winds up to 15 mph. Chance of rain 70 percent.

Monday: Mostly cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 80 to 88 near the shore to 66 to 71 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Monday Night: Mostly cloudy with scattered showers. Lows 64 to 72 near the shore to around 57 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Waikoloa

Tonight: Partly cloudy. Breezy. Lows around 77 near the shore to 53 to 58 above 4000 feet. East winds up to 20 mph.

Monday: Mostly sunny. Isolated showers in the afternoon. Highs 85 to 91 near the shore to 67 to 75 above 4000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Monday Night: Partly cloudy. Lows around 76 near the shore to 52 to 57 above 4000 feet. East winds up to 10 mph.

Detailed Forecast

Synopsis

Stable conditions and gentle to breezy trade winds will prevail through much of next week, with a brief weakening in wind speeds Monday through Tuesday. Typical scattered trade showers will focus along windward areas through the week with a slight boost for the eastern half of the state tonight through Monday.

Discussion

Visible satellite and radar imagery show a band of unstable clouds and scattered showers moving windward portions of Maui, while the remainder of the state sits under partly cloudy skies. The 00Z upper air soundings show inversion heights have risen a bit at Lihue and lowered a bit at Hilo, with both now sitting around 6000 feet, though relatively stable conditions remain in place. Surface high pressure far north of the state will continue to drive gentle to breezy trade winds across the islands with mainly scattered windward and mauka showers state-wide for the next several days.
A weak tropical wave southeast of the islands will help to raise local inversion heights slightly and drag an area of increased precipitable water through the southern portion of the state, allowing for more unstable clouds and a boost in trade wind showers, especially for windward areas of the Big Island and Maui County. Some of the stronger showers may move into the typically drier leeward locations at times. A brief drop in the trade wind speeds remains in the forecast for Monday and Monday night as a passing front near the Aleutians briefly displaces the high north of Hawaii off to the east a bit. Following this, the models indicate a fairly stable, moderate to locally breezy trade wind weather pattern through much of the rest of the week.
There remains a large degree of uncertainty in the weather pattern heading into next weekend due to potential tropical cyclone activity in the Central Pacific, east of Hawaii. The National Hurricane Center is forecasting a medium chance of tropical cyclone development in the East Pacific over the next seven days with westward movement into the Central Pacific by the end of next week. However, the GFS and ECMWF long-range model guidance differ significantly in the existence, position, and strength of activity near Hawaii at that time. Specific island forecast details from Friday onward will highly depend upon this potential tropical development.

Aviation

This afternoon, low clouds and showers that were common across windward coasts and slopes earlier today have largely diminished across both the far eastern and far western ends of the state. However, afternoon satellite imagery shows a band of low clouds and embedded showers continuing to stream into north through east sections of Maui. As a result, AIRMET Sierra for tempo mountain obscuration remains in effect for only portions of Maui at this time.
Tonight, a weak tropical wave moving through the region could increase showers and low clouds once again across windward and mountain areas of most islands. AIRMET Sierra may need to be expanded to account for an increase in MVFR ceilings and visibilities for these areas tonight.
Breezy trade winds continue to prevail across the state through tonight. AIRMET Tango remains in effect for moderate low level turbulence over and immediately downstream of island mountains. As a front passes well north of the main Hawaiian Islands on Monday, trades are expected to ease a bit before picking back up by midweek.

Marine

Moderate to locally strong trades will continue through Monday afternoon before briefly and subtly dropping off Tuesday. Easterly trades will strengthen to more fresh magnitudes across the majority of the waters through mid week in response to high pressure reestablishing itself north of the state. The Small Craft Advisory (SCA) remains in effect for the typically winder waters surrounding Maui County and south of Big Island through Monday afternoon. The SCA will likely need to be expanded further west later in the week as areawide trades pick up to more fresh speeds. There are moderate chances that a tropical cyclone will develop in the eastern Pacific the next seven days. If a tropical cyclone does develop, it will likely be traveling into the Central Pacific waters east or southeast of the Hawaiian Island chain late this week into early next week.
South-facing surf will begin lifting overnight as forerunners arrive ahead of a moderate size, long period south (190 degree) swell. The Samoa buoy observed this swell passage to be slightly above guidance as it peaked at around 9 feet Thursday afternoon HST. This should translate to reaching a local peak of 3 to 4 feet from Monday afternoon through Tuesday. This size swell increases the likelihood of pushing the highest surf heights to near advisory thresholds. Surf along the north and west-facing shores will also trend up Wednesday as a longer period northwest swell arrives from former Typhoon Ampil. This near 4 foot swell should peak out Wednesday through Thursday, then ease going into the weekend. East shore surf will remain somewhat choppy the next couple of days as a result of recently stronger trades over the islands. After a brief subsidence Tuesday, an upward trend in eastern shorter period chop will occur by the middle of the week as trades over and upstream of the state strengthen to more fresh magnitudes.
Minor tidal flooding will occur through Monday due to water levels running slightly higher than predicted during the peak monthly tides under a full moon.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Monday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov