Hilo

Today: Partly sunny with scattered light showers. Highs 80 to 85 near the shore to 66 to 71 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 62 to 70 near the shore to 53 to 58 at 4000 feet. East winds up to 10 mph. Chance of rain 90 percent.

Thursday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 79 to 85 near the shore to 65 to 71 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Kona

Today: Sunny in the morning, then mostly cloudy with scattered light showers in the afternoon. Highs 83 to 88 near the shore to 67 to 72 near 5000 feet. Southeast winds up to 10 mph shifting to the west in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then mostly clear with isolated showers after midnight. Lows around 72 near the shore to 49 to 55 near 5000 feet. Light winds. Chance of rain 50 percent.

Thursday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 82 to 87 near the shore to 66 to 71 near 5000 feet. North winds up to 10 mph shifting to the southwest around 10 mph in the afternoon. Chance of rain 50 percent.

Waimea

Today: Partly sunny with scattered light showers. Highs around 81 near the shore to 69 to 79 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 62 to 71 near the shore to 54 to 62 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs around 80 near the shore to 70 to 78 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Kohala

Today: Partly sunny with scattered light showers. Highs around 81 near the shore to 69 to 79 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 62 to 71 near the shore to 54 to 62 near 3000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs around 80 near the shore to 70 to 78 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

South Big Island

Today: Sunny in the morning, then mostly cloudy with isolated light showers in the afternoon. Highs around 85 near the shore to around 65 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows around 73 near the shore to around 51 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Thursday: Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs around 85 near the shore to around 64 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Puna

Today: Partly sunny with scattered light showers. Highs 80 to 85 near the shore to 66 to 71 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 62 to 70 near the shore to 53 to 58 at 4000 feet. East winds up to 10 mph. Chance of rain 90 percent.

Thursday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 79 to 85 near the shore to 65 to 71 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 70 percent.

Waikoloa

Today: Sunny. Highs 83 to 90 near the shore to 66 to 74 above 4000 feet. Northeast winds up to 15 mph shifting to the north in the afternoon.

Tonight: Mostly clear. Lows around 73 near the shore to 49 to 55 above 4000 feet. North winds up to 10 mph shifting to the east after midnight. Gusts up to 30 mph.

Thursday: Sunny. Highs 83 to 89 near the shore to 65 to 73 above 4000 feet. Northeast winds 10 to 15 mph shifting to the north in the afternoon.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will focus low clouds and brief showers over windward and mauka areas, especially during nights and mornings. Leeward communities will be mostly dry, but afternoon clouds and a few showers will develop over leeward portions of the Big Island. High clouds will occasionally transit island skies.

Discussion

Morning soundings show a strong and low subsidence inversion based between 5 and 7 thousand feet, with PWAT a seasonable 1.2″. Regional satellite images show scattered to locally broken low clouds streaming westward at about 17 kt/20 mph, with increased low cloud coverage noted over waters E of Maui County. Surface high pressure to the distant NE is supporting a moderate to breezy trade wind flow. Radar shows widely scattered relatively light showers, while infrared imagery shows thin high clouds streaming ENE over the islands from Oahu to Maui, associated with a persistent TUTT (tropical upper-tropospheric trough) NW of Kauai.
Model guidance has been consistent in projecting little significant change to the current pattern into next week. At the surface, trade wind speeds look to remain remarkably consistent near their current levels. In the mid-levels, a strong ridge will remain over the islands, keeping the subsidence inversion low and strong. Brief showers will favor windward areas, especially during nights and mornings, with sensible weather highly dependent on the arrival of difficult-to-anticipate low cloud clusters. We do anticipate that an area of increased low-level moisture (PWAT currently near 1.9″), associated with the remnants of former Hurricane Adrian now near 20N 130W, will move through the area Monday into Tuesday. This would bring an increase in primarily windward showers if it were to verify. Leeward areas will remain mostly dry, except for the typical afternoon clouds and showers on the Big Island's leeward slopes, but even these should be limited.
There are some changes expected in the upper-level pattern, but impacts on sensible weather will likely be negligible. The nearly- stationary TUTT NW of Kauai will begin to move E later today, passing over the islands tonight and Thursday. This will bring periods of high clouds into Thursday, and some instability aloft, but it is highly unlikely that surface parcels tap into this. There could be some low-impact afternoon cloud/shower formation over the Big Island's summits and upper slopes Thursday. A new low developing within the TUTT this weekend may lead to more high clouds streaming over the islands within the associated subtropical jet.

Aviation

Moderate to locally breezy trade winds are expected to persist today and tonight. The atmosphere remains relatively dry and stable across the island chain early this morning. There are patches of scattered to broken low clouds with embedded isolated light showers being transported by the low-level trade wind flow into the windward sides of some of the islands. This may produce brief periods of MVFR conditions along some windward facing slopes and coastal areas, but VFR conditions will likely prevail across most of the state today.
No AIRMETs are currently in effect. We are monitoring observations from the VAD wind profiles in case we need to issue AIRMET Tango for moderate low-level mechanical turbulence later today.

Marine

A high pressure ridge will remain locked in place far north of the Hawaii region, producing moderate to locally strong trade winds over and upstream of the Hawaiian Islands lasting into early next week. A Small Craft Advisory (SCA) was extended in time through Thursday night for the typically windier waters around Maui County and the Big Island. This SCA will likely continue through the weekend.
Surf along all shores are expected to remain tiny through Friday. In the long range, a series of moderate period south-southeast (150 degree) to south (190-200 degree) swells are expected starting this weekend producing a good boost to south shore surf heights. Another long period south (180-190 degree) swell will move into the region from Monday to Tuesday of next week. North facing shores may see a slight pulses out of the north-northwest (330 degree) through the weekend keeping surf above flat levels starting on Friday.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov