Photo Credit: James Grenz

Hilo

Today: Mostly sunny in the morning then becoming partly sunny. A 20 percent chance of showers. Highs 78 to 84 near the shore to 64 to 73 at 4000 feet. Northeast winds 10 to 15 mph.

Tonight: Mostly cloudy with a 50 percent chance of showers. Lows 65 to 72 near the shore to 55 to 61 at 4000 feet. North winds around 10 mph.

Thursday: Partly sunny with scattered showers. Highs 78 to 83 near the shore to 63 to 71 at 4000 feet. Northeast winds around 10 mph. Chance of rain 50 percent.

Kona

Today: Sunny in the morning, then mostly cloudy with a 20 percent chance of showers in the afternoon. Highs 80 to 88 near the shore to around 71 near 5000 feet. Light winds becoming west 10 to 15 mph in the afternoon.

Tonight: Mostly cloudy with a 20 percent chance of showers in the evening, then mostly clear after midnight. Lows 70 to 75 near the shore to 49 to 55 near 5000 feet. Light winds.

Thursday: Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs 80 to 88 near the shore to around 71 near 5000 feet. Light winds becoming west 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Waimea

Today: Mostly sunny with a 20 percent chance of showers. Highs 67 to 88. East winds 10 to 15 mph.

Tonight: Partly cloudy with a 40 percent chance of showers. Lows 64 to 71 near the shore to 54 to 62 near 3000 feet. East winds 10 to 15 mph.

Thursday: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 66 to 88. East winds 10 to 15 mph. Chance of rain 40 percent.

Kohala

Today: Mostly sunny with a 20 percent chance of showers. Highs 67 to 88. East winds 10 to 15 mph.

Tonight: Partly cloudy with a 40 percent chance of showers. Lows 64 to 71 near the shore to 54 to 62 near 3000 feet. East winds 10 to 15 mph.

Thursday: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 66 to 88. East winds 10 to 15 mph. Chance of rain 40 percent.

South Big Island

Today: Sunny in the morning, then mostly cloudy with a 20 percent chance of showers in the afternoon. Highs 81 to 87 near the shore to around 69 near 5000 feet. East winds 10 to 15 mph.

Tonight: Mostly cloudy in the evening then clearing. Lows around 73 near the shore to around 51 near 5000 feet. Northeast winds 10 to 15 mph.

Thursday: Sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs 81 to 87 near the shore to around 68 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Puna

Today: Mostly sunny in the morning then becoming partly sunny. A 20 percent chance of showers. Highs 78 to 84 near the shore to 64 to 73 at 4000 feet. Northeast winds 10 to 15 mph.

Tonight: Mostly cloudy with a 50 percent chance of showers. Lows 65 to 72 near the shore to 55 to 61 at 4000 feet. North winds around 10 mph.

Thursday: Partly sunny with scattered showers. Highs 78 to 83 near the shore to 63 to 71 at 4000 feet. Northeast winds around 10 mph. Chance of rain 50 percent.

Waikoloa

Today: Sunny. Highs 80 to 91 near the shore to 68 to 75 above 4000 feet. North winds 10 to 15 mph.

Tonight: Mostly clear. A 20 percent chance of showers in the evening. Lows around 73 near the shore to 50 to 56 above 4000 feet. Northeast winds around 10 mph.

Thursday: Mostly sunny. Isolated showers in the afternoon. Highs 79 to 89 near the shore to 67 to 74 above 4000 feet. North winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Light to moderate trade winds will remain on the dry side of normal for most areas through Thursday, but moisture associated with a dissipating front may bring an increase in windward showers to Kauai beginning tonight. An increase in windward showers is possible for most islands Thursday night and Friday as moisture arrives from the east. Light and variable winds this weekend may bring increased afternoon showers to island interiors, with generally dry conditions at night.

Discussion

A mostly dry and stable trade wind weather pattern remains in place this morning, with latest satellite images showing abnormally few low clouds upstream of the islands from Kauai to Maui, with scattered low clouds approaching the Big Island. Radar shows little in the way of precipitation, and the rain gage network has remained mostly dry over the past 24 hours. A mid- and upper level ridge centered NW of the islands is supporting a strong subsidence inversion based near 6000' over the Big Island, while the Lihue sounding showed a weaker inversion, with PWAT near 1.2″ in Hilo and 1.5″ in Lihue. Little change is expected in the short term, with very little rainfall anticipated today.
Model guidance over the past 48 hours has been advertising an increase in PWAT near Kauai as remnants of a front, now about 150 miles N of Kauai, sags S. This has yet to occur, with nearly clear skies at the moment, but guidance continues to indicate an increase in low-level moisture around Kauai by tonight. If this occurs, there will be some increase in trade wind shower coverage over windward Kauai, while mostly dry conditions persist over the remainder of the state through Thursday.
An uptick in trade wind shower coverage is possible over most islands Thursday night and Friday as moisture associated with a low- level trough presently near 20N 150W moves over the area. Current guidance keeps the bulk of this moisture N of the Big Island. Over the weekend, a slow-moving cut-off low far NE of the islands will send a front southward toward the area, substantially weakening the local pressure gradient. Light E winds will allow land and sea breezes to modulate weather over land. With some moisture lingering and with converging afternoon sea breezes, there could be a healthy coverage of afternoon clouds and showers over interior sections over the weekend. Overnight land breezes should bring clearing each night and morning. Increased moisture associated with the approaching front may move over some of the islands from the N early next week as trade winds restrengthen.

Aviation

High pressure north of the state will maintain moderate trade winds through the forecast period. A relatively dry airmass will limit cloud and shower activity to windward areas. Expect mainly VFR conditions, with brief MVFR possible under passing showers.
No AIRMETs are in effect.

Marine

A weak frontal boundary north of the Hawaiian Islands will diminish today and a high pressure system far to the northeast of the region will produce moderate to fresh trade winds through Thursday. Wind speeds will then weaken from Friday through Monday, as yet another low pressure system sets up north of the region. Wind speeds will likely remain below Small Craft Advisory thresholds through Monday.
A series of small to medium period north and northwest swells from Aleutian sources are expected to increase surf heights along north facing shores through Friday. Medium range guidance shows a cut off low forming far north of the state on Thursday and Friday, sending a north swell towards the islands arriving by Saturday night. A decent fetch area will point towards Hawaii with 20 to 35 knots of wind developing around the west side of the low center. However, the strength of this north swell energy will greatly depend on where and how strong this surface low sets up relative to the island chain. Stay tuned.
South swell will continue trend a bit lower today before another small background south swell fills in on Thursday with slight increasing trends expected on Friday and Saturday. A slightly larger, medium period south-southeast swell will arrive by early next week.
East facing shores will remain small over the next week, with a potential for a small north swell wrap by Sunday.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov