Hilo

Tonight: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Haze through the night. Lows 61 to 68 near the shore to 49 to 56 at 4000 feet. South winds up to 10 mph. Chance of rain 70 percent.

Thursday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Haze through the day. Highs around 80 near the shore to 64 to 69 at 4000 feet. Southeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Thursday Night: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Haze. Lows 61 to 69 near the shore to 50 to 55 at 4000 feet. Southeast winds around 10 mph in the evening becoming light. Chance of rain 20 percent.

Kona

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Haze through the night. Lows around 70 near the shore to 44 to 51 near 5000 feet. Light winds. Chance of rain 40 percent.

Thursday: Mostly sunny. Haze through the day. Isolated showers in the afternoon. Highs around 84 near the shore to around 66 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Thursday Night: Partly cloudy. Haze. Lows around 70 near the shore to 45 to 51 near 5000 feet. Light winds.

Waimea

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Haze through the night. Lows 61 to 69 near the shore to 52 to 59 near 3000 feet. Light winds. Chance of rain 50 percent.

Thursday: Mostly sunny with isolated showers. Haze. Highs around 79 near the shore to 70 to 76 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Thursday Night: Partly cloudy. Isolated showers in the evening. Haze through the night. Lows 60 to 69 near the shore to 52 to 59 near 3000 feet. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Kohala

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Haze through the night. Lows 61 to 69 near the shore to 52 to 59 near 3000 feet. Light winds. Chance of rain 50 percent.

Thursday: Mostly sunny with isolated showers. Haze. Highs around 79 near the shore to 70 to 76 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Thursday Night: Partly cloudy. Isolated showers in the evening. Haze through the night. Lows 60 to 69 near the shore to 52 to 59 near 3000 feet. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

South Big Island

Tonight: Mostly cloudy with scattered showers. Haze. Lows around 72 near the shore to around 50 near 5000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Thursday: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Haze through the day. Highs around 84 near the shore to around 66 near 5000 feet. East winds up to 20 mph. Chance of rain 40 percent.

Thursday Night: Mostly clear. Haze. Lows around 71 near the shore to around 49 near 5000 feet. East winds 10 to 15 mph.

Puna

Tonight: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Haze through the night. Lows 61 to 68 near the shore to 49 to 56 at 4000 feet. South winds up to 10 mph. Chance of rain 70 percent.

Thursday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Haze through the day. Highs around 80 near the shore to 64 to 69 at 4000 feet. Southeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Thursday Night: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Haze. Lows 61 to 69 near the shore to 50 to 55 at 4000 feet. Southeast winds around 10 mph in the evening becoming light. Chance of rain 20 percent.

Waikoloa

Tonight: Mostly clear. Haze. Lows around 70 near the shore to 47 to 53 above 4000 feet. Light winds.

Thursday: Mostly sunny. Haze through the day. Scattered showers in the afternoon. Highs 81 to 87 near the shore to 64 to 70 above 4000 feet. West winds up to 10 mph. Chance of rain 40 percent.

Thursday Night: Partly cloudy. Haze. Lows 68 to 73 near the shore to 48 to 54 above 4000 feet. Light winds.

Detailed Forecast

Synopsis

Light to occasionally moderate east to southeasterly winds are expected to persist through the remainder of the week and into the weekend. Light showers will focus across windward areas during the overnight hours and leeward and interior areas during the afternoon hours. A deep upper-level low is progged to approach the islands early next week, potentially enhancing southerly winds to the area. However, confidence remains low in the forecast for next week at this time.

Discussion

This afternoon, mostly dry conditions are observed across the island chain. At the surface, a frontal boundary lies outside of the offshore waters to the north and northeast, while a ridge axis near the islands is supporting stable conditions across Hawaii. Afternoon surface observations and a late morning advanced scatterometer (ASCAT) pass show light to moderate east- southeasterly background flow prevailing. Due to the relatively light background winds, sea-breeze induced clouds have developed over interior and leeward sections of the islands this afternoon, though rainfall amounts have been scarce, and where a few showers have occurred, amounts have been very light. Afternoon upper air soundings from Lihue and Hilo show stable, mostly dry profiles with inversions around 7,000 feet.
This evening and tonight, the light southeasterly background winds will continue, prompting overnight land breezes similar to those that occurred last night. This will clear the islands of most clouds and shower activity, though a few showers will remain possible along east and southeast slopes and coasts.
For the rest of this week and into the weekend, a hybrid land/sea breeze pattern, with moderate trade winds at times, will continue as the next front moves toward the island chain and broad upper- level ridging prevails east of the state. Background winds will remain light to occasionally moderate from the southeast for the remainder of the week, keeping most of the smaller islands relatively dry since they will be largely shadowed by the Big Island. While some showers will still be carried into windward areas of the smaller islands on the east to southeast winds, the lighter flow will allow sea breezes to increase clouds and support a few light showers for leeward and interior areas each afternoon. Land breezes will then clear clouds and showers over these leeward and interior areas each night.
By next week, model guidance suggests a deep, upper-level low will develop northwest of the islands. However, there are significant differences amongst model guidance regarding the strength, positioning, and timing of this feature, creating a lot of uncertainty for the forecast beyond this weekend. For example, the ECMWF introduces a more progressive solution, with this feature quickly moving off to the northeast on Monday and then lingering far north of the islands with a front approaching the northern end of the state Tuesday into Wednesday. However, the GFS keeps the feature stalled northwest of the islands through the middle of next week. These differences would have significant impacts on moisture availability and the prevailing wind speed and direction over the main Hawaiian Islands. Some changes were made to the forecast in the long term to trend towards the latest guidance, though have continued with the general theme of relatively dry conditions for most islands, and Kauai having the highest shower chances by the middle of next week.

Aviation

Light to moderate southeasterly winds will produce land/sea breezes over all islands. A few leeward SHRA and some isol MVFR conds can be expected today with land breezes tonight. VFR should generally prevail.
No AIRMETs are currently in effect.

Marine

A weak ridge of high pressure oriented northwest to southeast over the islands will gradually strengthen over the next few days. This will result in several days of generally light to gentle easterlies, with the exception of slightly higher winds over the windward Maui and Big Island surrounding waters. Near shore, localized sea breezes will likely predominate during the day and light offshore winds at night. Early next week, a strong cold front will approach from the west causing causing winds to veer to the south or southwest over the western half of the state.
The current north northwest (330-350 degree) swell will continue to fade even as a new medium period swell out of the north northeast (010-030) builds in. This will provide a slight boost in north- facing shore surf with many sets coming in waist to head high Friday and Saturday. For the coming week, a series of multiple small north and northwest swells will keep surf along along north and west facing shores near seasonal norms.
South-facing shores should remain small with some background long period south southwest swell expected to arrive Thursday or Friday. East-facing shore chop will also remain small due to the absence of any significant trade fetch. However, select east-facing exposures may see a small bump in surf due to wrap from the north- northeast swells tomorrow and Friday.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov