Photo Credit: Brendan Stephen

West Kaua’i

Today: Sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 87 near the shore to around 75 above 3000 feet. East winds up to 15 mph shifting to the southeast in the afternoon. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows 69 to 74 near the shore to around 60 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Friday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs around 87 near the shore to around 75 above 3000 feet. North winds up to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Breezy. Partly sunny with scattered showers. Highs around 84. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with numerous showers. Lows 67 to 73. Northeast winds 10 to 20 mph. Chance of rain 70 percent.

Friday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs around 84. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Breezy. Scattered showers in the morning, then showers in the afternoon. Highs 74 to 81 in the valleys to around 65 above 4000 feet. East winds up to 20 mph. Chance of rain near 100 percent.

Tonight: Showers. Lows 60 to 65 in the valleys to around 55 above 4000 feet. East winds up to 15 mph. Chance of rain near 100 percent.

Friday: Partly sunny. Showers in the morning, then scattered showers in the afternoon. Highs 74 to 81 in the valleys to around 65 above 4000 feet. East winds up to 15 mph. Chance of rain 90 percent.

North Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 77 to 86. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Numerous showers in the evening, then scattered showers after midnight. Lows 63 to 73. East winds up to 15 mph. Chance of rain 70 percent.

Friday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 77 to 86. East winds up to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Partly sunny. Scattered showers in the morning, then numerous showers in the afternoon. Highs 77 to 85. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Showers. Lows 61 to 74. Northeast winds 10 to 15 mph decreasing to up to 10 mph after midnight. Chance of rain near 100 percent.

Friday: Partly sunny with scattered showers. Highs 77 to 85. Northeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Detailed Forecast

Synopsis

The high pressure ridge far north of the islands will weaken and cause trade winds to decrease into more moderate levels from through the upcoming weekend. A weak low level trough moving through the islands will continue to enhance clouds and showers through the morning hours as it slowly drifts westward. Another weak low level trough passing from east to west across the island chain may enhance shower activity this weekend. High pressure will build in from the north on Monday with increasing trade wind speeds and more stable weather conditions lasting through next Wednesday.

Discussion

The large scale weather pattern remains the same this morning. Global satellite imagery (water vapor channel) around the Hawaii region shows a narrow west to east upper level trough just north of the island chain with a few embedded weak lows. High level cirrus clouds south of the state outline the subtropical jet stream. Infra-red images show a broad cloud band with cloud tops from 9,000 to 12,000 feet developing along a weak low level trough slowly passing westward through the Hawaiian Islands. This low level trough will continue to enhance clouds and shower activity through the morning hours.
The high pressure ridge far north of the state will slowly weaken in response to middle latitude cold fronts passing from west to east farther north of the ridge axis. This means trade winds will slowly decrease into more moderate wind speeds through the weekend. Short range model streamlines (at 700 mb) continue to show another weak tropical wave drifting from east to west through the islands this weekend. This passing trough will increase low level cloud heights and may lead to increasing shower trends on Saturday and Sunday. We increased our precipitation chances for this weekend in the morning 12z grid package to show these wetter trends.
In the long range forecast, global models appear in good agreement that the high pressure ridge builds in north of the region starting on Monday. This means we return to a stronger trade wind pattern with wind speeds in the moderate to breezy range across the state at least through next Wednesday. More stable conditions return with the building trade winds with shower trends favoring windward and mountain areas in the typical overnight to early morning hours.

Aviation

High pressure north of the state will allow moderate to locally breezy tradewinds to persist through the remainder of this morning. Some deeper moisture in the low levels will advect towards the islands today and bring scattered showers to windward locations with isolated showers expected elsewhere. Trade flow will weaken slightly by this afternoon.
AIRMET SIERRA remains in effect for north through east sections of the Big Island for tempo mountain obscuration above 2500 feet due to clouds and showers.
AIRMET TANGO remains in effect below 8000 feet for areas over and immediately south through west of mountains due to tempo moderate turbulence.

Marine

Moderate to fresh easterly trade winds with localized areas of strong winds will continue each day through early next week as the surface ridge remains in place to the north. The Small Craft Advisory in effect for the the typically windier waters between Maui County and the Big Island will continue through Friday, and may need to be extended through the weekend.
Surf along south facing shores has returned to the typical summertime average, and that is reflected in the early morning observations at the nearshore/offshore buoys. Expect this trend to persist through early next week with mainly background south and south-southeast swells expected. For the long range, guidance is depicting plenty of activity unfolding around New Zealand within our swell window that could generate pulses of south- southwest swell toward the islands. If this evolves as predicted, expect an upward trend next weekend (Jul 8-12). Confidence in the details will improve this weekend into early next week.
Surf along east facing shores will remain small and choppy each day through early next week.
Surf along north and west facing shores will remain near the summertime average each day with mainly background north- northwest swell expected through Friday.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov