Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny. Highs around 91 near the shore to around 79 above 3000 feet. East winds up to 15 mph.

Tonight: Partly cloudy. Lows around 73 near the shore to around 63 above 3000 feet. East winds around 10 mph.

Tuesday: Mostly sunny. Highs around 91 near the shore to around 79 above 3000 feet. East winds up to 10 mph.

South Kaua’i

Today: Partly sunny. Breezy. Isolated showers in the morning. Highs 83 to 90. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows around 74. East winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday: Partly sunny. Isolated showers in the morning. Highs 84 to 91. East winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 76 to 87 in the valleys to around 69 above 4000 feet. East winds up to 15 mph. Chance of rain 70 percent.

Tonight: Cloudy. Scattered showers in the evening, then showers after midnight. Lows 65 to 72 in the valleys to around 60 above 4000 feet. East winds 10 to 15 mph. Chance of rain 90 percent.

Tuesday: Cloudy. Numerous showers in the morning, then scattered showers in the afternoon. Highs 76 to 87 in the valleys to around 69 above 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

North Kaua’i

Today: Partly sunny with isolated showers. Highs 78 to 91. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows 67 to 74. East winds around 10 mph. Chance of rain 20 percent.

Tuesday: Partly sunny with isolated showers. Highs 79 to 91. East winds 10 to 15 mph. Chance of rain 20 percent.

East Kaua’i

Today: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 76 to 87. Northeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with isolated showers. Lows 66 to 77. East winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 77 to 88. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

A high pressure surface ridge north of the islands will keep moderate to locally breezy easterly trade winds in the forecast through Wednesday. A low pressure system moving in far to the north of the island chain will break down this ridge, decreasing wind speed trends from Thursday on into the weekend. An easterly wave will move through the islands by this weekend increasing cloud and shower trends across the state.

Discussion

Fairly stable bands of clouds are drifting through the Hawaiian Islands on the easterly trade winds in the early morning hours. Upper air balloon soundings from 2 AM HST (12Z) this morning show subsidence temperature inversion height around the 6,000 foot level at both Lihue, Kauai and Hilo, Hawaii. These stable conditions aloft will limit vertical cloud and shower development through Friday. Brief shower activity will favor windward and mountain areas in the overnight to early morning hours. Long range model solutions continue to show a trough marching from east to west through the islands by this weekend; likely boosting cloud and shower activity through Sunday.
In the larger scale weather pattern, the surface ridge will remain north of the islands this week, keeping moderate to locally breezy easterly trade winds in the forecast through Wednesday. A low pressure system developing far north of the state on Thursday, will break down the ridge and weaken wind speeds across the region into the early next week. Expect mid morning through afternoon onshore sea breezes to expand in coverage as the large scale winds weaken across the region. Sea breezes will build clouds over interior sections of each island during the day with a some enhanced shower activity over typically drier leeward areas, especially this weekend as the afternoon sea breezes interact with the passing trough forecast to move through the state.

Aviation

Trade winds will remain moderate to locally strong through at least mid-week. Embedded showers will favor windward and mauka areas. Isolated spillover showers are to be expected across the smaller islands this morning. On the Big Island, afternoon and early evening cloud cover may generate moderate showers along south and west facing slopes.
AIRMET Tango remains in effect for mid-level turbulence over and immediately south through southwest of Big Island Summits due to strong winds above the inversion layer. Another AIRMET Tango is in effect for low levels immediately south and west of all islands due to the breezy trade winds. No other AIRMETS are in effect.

Marine

A surface ridge along 27-28N will support moderate to locally strong trade winds through midweek. The ridge may weaken somewhat thereafter, with trade wind speeds slowly diminishing in response. A Small Craft Advisory posted for most waters around Maui and the Big Island will likely remain in place through at least Wednesday.
The medium-period S swell of the past several days continues to move through island waters, with offshore and nearshore buoys indicating a fresh pulse of swell that will continue to support elevated surf today. A slow trend down is expected Tuesday into Wednesday. A small, longer-period SSW swell is expected next weekend.
A small, short-period (~10 seconds) NNW swell will peak today, then diminish Tuesday into Wednesday. Another small, short-period NNW swell may arrive around Thursday. Short-period wind waves will support small to moderate surf along E facing shores for the next couple of days. Small, long-period E swells from increased E Pacific tropical cyclone activity may arrive from Wednesday onward, leading to a subtle increase in surf heights.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Tuesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov