Hilo

Today: Mostly cloudy with scattered showers. Highs around 83 near the shore to 66 to 71 at 4000 feet. Southeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 65 to 70 near the shore to around 54 at 4000 feet. Southeast winds around 10 mph. Chance of rain 30 percent.

Friday: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 66 to 71 at 4000 feet. Southeast winds around 10 mph. Chance of rain 50 percent.

Kona

Today: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 81 to 86 near the shore to around 66 near 5000 feet. Northeast winds 10 to 15 mph shifting to the west in the afternoon. Chance of rain 40 percent.

Tonight: Mostly cloudy. Isolated showers in the evening. Lows 68 to 75 near the shore to around 55 near 5000 feet. Northeast winds around 10 mph in the evening becoming light. Chance of rain 20 percent.

Friday: Mostly cloudy. Scattered showers in the afternoon. Highs 81 to 86 near the shore to around 66 near 5000 feet. Southwest winds up to 10 mph shifting to the northwest around 10 mph in the afternoon. Chance of rain 50 percent.

Waimea

Today: Mostly cloudy with scattered showers. Highs around 82 near the shore to 66 to 77 near 3000 feet. Southeast winds around 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows around 67 near the shore to 55 to 62 near 3000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Friday: Mostly cloudy with scattered showers. Highs around 82 near the shore to 66 to 77 near 3000 feet. East winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Kohala

Today: Mostly cloudy with scattered showers. Highs around 82 near the shore to 66 to 77 near 3000 feet. Southeast winds around 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows around 67 near the shore to 55 to 62 near 3000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 40 percent.

Friday: Mostly cloudy with scattered showers. Highs around 82 near the shore to 66 to 77 near 3000 feet. East winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

South Big Island

Today: Breezy. Mostly cloudy with scattered showers. Highs around 84 near the shore to around 70 near 5000 feet. East winds 15 to 20 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening. Lows around 69 near the shore to around 54 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Friday: Mostly cloudy. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 84 near the shore to around 70 near 5000 feet. East winds 10 to 20 mph. Chance of rain 40 percent.

Puna

Today: Mostly cloudy with scattered showers. Highs around 83 near the shore to 66 to 71 at 4000 feet. Southeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 65 to 70 near the shore to around 54 at 4000 feet. Southeast winds around 10 mph. Chance of rain 30 percent.

Friday: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 83 near the shore to 66 to 71 at 4000 feet. Southeast winds around 10 mph. Chance of rain 50 percent.

Waikoloa

Today: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 85 near the shore to 67 to 73 above 4000 feet. Northeast winds around 10 mph shifting to the west in the afternoon. Chance of rain 40 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows 69 to 75 near the shore to 51 to 58 above 4000 feet. Light winds. Chance of rain 20 percent.

Friday: Partly sunny. Scattered showers in the afternoon. Highs around 85 near the shore to 67 to 73 above 4000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Lingering clouds and showers will persist across the state today. The threat for flooding and heavy rain is greatest over Kauai, but expecting improving conditions by this afternoon. Brief periods of locally heavy rain are possible through Friday statewide. A more typical trade wind pattern is expected by Sunday.

Discussion

The stalled front near the western end of the state continues to bring clouds and showers to the region, however the bulk of the showers have moved through. There has been a noticeable downtrend in rainfall across Kauai, Oahu and the islands of Maui County overnight. However, satellite shows another band of clouds to the northwest of Kauai. Radar is not picking up much in the way of showers with this band, especially in comparison to the area that moved through overnight, however the high resolution and global models are all in good agreement with more showers expected.
Knowing that the ground on Kauai got decent saturation yesterday and last night, will be leaving the Flash Flood Watch in effect for today. Anticipate improving conditions, however with the saturated grounds, any heavy rainfall could cause localized problems. The overnight sounding from Kauai shows a substantial decrease in instability, as was expected. Still keeping the mention of a slight chance of a thunderstorm in through this morning, but confidence is low that any will depend.
The main area of clouds and rain has moved down the island chain and has thinned some over night. Radar shows rain has diminished in this area as it has moved over Maui County and the Big Island. Rain gages across those areas indicate only a few hundredths inches of rain has been received.
Have made some tweaks to the forecast, but as expected, no discernible changes to the overall forecast philosophy with the morning package. As the associated low lifts northeastward on Friday, we can expect the southerly flow to weaken, giving way to some afternoon sea breezes. The low level moisture will remain focused over Kauai and Oahu, which means afternoon showers could be heavier than normal at times. Trade winds should return over the eastern half of the state Saturday, and spread to the remainder of the state by Saturday night. Drier trade wind weather will return by early next week as surface ridging shifts westward and upper troughing near the islands becomes zonal.

Aviation

A rather diffuse frontal boundary appears to be less than 150 nm west-northwest of Kauai early this morning. A northeast to southwest oriented surface ridge is also in the vicinity of the Big Island. The tight pressure gradient between these two features is producing strong south to southwest winds across the the western islands. This strong flow will continue to transport abundant moisture up into the state. This excess moisture combined with unstable atmospheric conditions will support clouds and showers this morning, with the greatest threat of locally heavy rainfall and thunderstorms near the westernmost islands. The band of layered mid- and upper-level clouds, which was over the western and central islands last evening, has pushed east over Maui and the Big Island early this morning. There is mainly stratiform rain falling from some of these layered middle and high clouds. This band will continue to move east today. Additional upper-level clouds are also moving in from the west over the state, so expect high cloud cover to prevail over many areas this morning.
Local sea breezes are possible over some sections of the state this afternoon, especially if the middle and high clouds thin out later this morning. This could lead to cloud build ups and showers over some areas, in addition to clouds and showers being transported within the deep southerly flow. Widespread MVFR conditions remain possible over most of Kauai and Niihau today. Low clouds and showers and may also develop in the vicinity of Oahu, so periods of MVFR conditions are possible there through this afternoon. Brief periods of MVFR conditions may occur over some sections of Maui County and the Big Island today.
AIRMET Sierra for mountain obscuration continues for Kauai and Lanai. This AIRMET may be needed for additional islands later today. In addition, AIRMET Zulu notes that TEMPO light icing is possible this morning in clouds for the entire area within the layer from 14,500 to 25,000 feet.
By tonight, local land breezes may reduce the coverage of low clouds and showers over some of the islands. However, there remains a chance of clouds and showers through early Friday morning, since the unusual moist conditions will remain, even though some gradual stabilization of the atmosphere may begin to develop.

Marine

Strong southerly winds will continue over Kauai waters through today as a slow moving cold front stalls just west of the island of Kauai. These southerly winds and a long period south swell are producing rough seas over southern leeward waters near Kauai and Niihau that are normally protected during a typical trade wind weather pattern. A Small Craft Advisory (SCA) remains in effect for all waters around Kauai including the Kauai Channel through the afternoon. Expect locally higher winds and seas near heavy showers and thunderstorms. The latest model guidance shows the front weakening as it lifts northward later this evening with a sharp drop in southerly wind speeds expected. The SCA will likely be dropped for the western waters near Kauai by tonight. A high pressure ridge will begin to build back in over the region on Friday with trade winds strengthening from east to west across the area through the weekend. SCA conditions will likely return to the typical windier waters and channels near Maui and Hawaii Counties on Saturday and Sunday.
Surf heights along south facing shores will remain elevated into the weekend as the current south swell becomes reinforced today. In the long range, models show quite a bit of activity in the southern hemisphere, which could translate to a few south shore surf events over the next week or so.
Surf along north and west facing shores will trend up today as a small, medium-period northwest (300-320 degrees) swell arrives. A return to small, summer-like conditions is expected over the weekend and into the first half of next week as this swell energy fades.

HFO Watches/Warnings/Advisories

Flood Watch through this afternoon for Niihau, Kauai,
Small Craft Advisory until 6 PM HST this evening for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel.

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Data Courtesy of NOAA.gov