Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Sunny. Isolated showers in the afternoon. Highs around 82 near the shore to around 70 above 3000 feet. Light winds becoming south up to 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 66 to 71 near the shore to around 57 above 3000 feet. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Wednesday: Mostly sunny. Isolated showers in the morning. Highs around 82 near the shore to around 70 above 3000 feet. Northeast winds around 10 mph in the morning becoming light. Chance of rain 20 percent.

South Kaua’i

Today: Sunny. Highs 78 to 85. Northeast winds up to 10 mph.

Tonight: Breezy. Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows around 68. Northeast winds 15 to 20 mph. Chance of rain 40 percent.

Wednesday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 79 to 85. Northeast winds 10 to 15 mph. Chance of rain 30 percent.

Kaua’i Mountains

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs 70 to 77 in the valleys to around 62 above 4000 feet. North winds up to 15 mph. Chance of rain 30 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 59 to 66 in the valleys to around 55 above 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Wednesday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 71 to 77 in the valleys to around 62 above 4000 feet. Northeast winds around 10 mph in the morning becoming light. Chance of rain 50 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 72 to 81. Northwest winds 10 to 15 mph shifting to the north in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 61 to 69. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Wednesday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 73 to 81. Northeast winds around 10 mph. Chance of rain 40 percent.

East Kaua’i

Today: Mostly sunny with isolated showers. Highs 71 to 81. North winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 60 to 71. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Wednesday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 71 to 81. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Detailed Forecast

Synopsis

The tail end of a weak front will approach the islands tonight, and progress down the island chain through Thursday. Light winds today will give way to trade winds behind the front. Stable conditions aloft will limit overall rainfall, with showers focused over windward slopes.

Discussion

Minor changes to the forecast with the morning package. While there are some radar returns, rain gages show very little making it to the ground. As such have lowered PoPs for this morning. Made some minor tweaks to the PoPs tonight through tomorrow night to trend today the latest blend of the models.
No changes in the forecast philosophy this morning. Light winds continue across the islands early this morning, with overnight land breezes helping to clear out the skies over most areas. A low strong low pressure system is more than 1000 miles east northeast of the islands, with the associated cold front about 500 miles to the northwest. The leading edge of the cloud band is about 350 miles to the northwest. The low is expected to move to the east and then lift to the northeast tomorrow morning. This will drag the front towards the islands, and boost low level moisture near the islands. Although this increase will boost showers, the bulk of the moisture looks to stay on the eastern side of the islands. As high pressure moves north of the islands tonight, look for northerly winds to filter in, and then transition to trades. This will help to focus showers on the windward sides of the islands. Despite the increase in moisture, ridging will remain aloft, limiting rainfall totals. So expect more showers than we have seen recently, but don't expect a lot of rain.
Look for the moisture to reach Kauai tonight, and then spread to the smaller islands by tomorrow, and the Big Island later tomorrow night. Moisture will linger near Maui County and the Big Island Wednesday.
The high pressure system moving in behind the front will maintain a moderate trade wind pattern for the end of the week, again with limited shower activity.

Aviation

Land breezes will give way to increasing north to northeast winds later today as a front approaches from the northwest. Shower activity will remain minimal and confined mainly to the coastal waters and locations near the immediate coast this morning. A few showers will be possible over the island interiors this afternoon, and showers will likely increase over Kauai late this afternoon as the front nears. The front is expected to move southward into the smaller islands tonight, bringing a notable increase in showers along with some reduced cigs and vsbys, particularly to windward areas.
No AIRMETs are in effect and none are anticipated through most of today. AIRMET Sierra may be required for windward sections of Kauai by late this afternoon and will likely expand to windward areas of the other smaller islands tonight.

Marine

The High Surf Warning has been downgraded to a High Surf Advisory (HSA) for most north and west facing shores of the smaller islands. The HSA for west facing shore of the Big Island has been cancelled along with the Small Craft Advisory as the current northwest swell continues to gradually subsides today. Overlapping northwest (330-340 degrees) and north- northwest (340-350 degrees) pulses will fill in late tonight through Wednesday keeping surf elevated along north and west facing shores. The HSA may need to be extended through tomorrow if these pulses come in larger than guidance. These swells will trend down Thursday through Friday. A small northwest swell (320 degrees) and small north- northeast swell (20-30 degrees) is possible Friday night through the coming weekend.
South facing shores remain small due to a small south- southwest swell (200 degrees) moving through today and tomorrow. Small surf along east facing shores may trend up through the rest of the week as trades return and more northerly and northeasterly pulses move through the state, mentioned above.
Gentle to moderate northerly winds will bleed through an approaching front from the northwest today. Expect moderate northeast winds to eventually spread down over the state later this afternoon and Wednesday as the front weakens and dissipates over or near the central waters. High pressure will build in behind the front, with gentle to moderate trade winds prevailing through the end of the week.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST this evening for north and west facing shores of Niihau, Kauai, Oahu, Molokai and north facing shores of Maui.

Data Courtesy of NOAA.gov