Photo Credit: Braden Jarvis

West Kaua’i

Today: Mostly sunny. Highs around 90 near the shore to around 78 above 3000 feet. Northeast winds up to 15 mph shifting to the west in the afternoon.

Tonight: Partly cloudy. Lows around 73 near the shore to around 63 above 3000 feet. Northeast winds up to 15 mph.

Monday: Mostly sunny. Highs around 91 near the shore to around 79 above 3000 feet. East winds up to 15 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: Breezy. Mostly cloudy with isolated showers. Lows around 74. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Monday: Partly sunny. Breezy. Isolated showers in the morning. Highs 82 to 90. Northeast winds 10 to 20 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 10 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 up to 15 mph. Chance of rain 90 percent.

Monday: 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.

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 75. East winds up to 15 mph shifting to the southeast after midnight. Chance of rain 20 percent.

Monday: Partly sunny with isolated showers. Highs 78 to 91. East winds up 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 75 to 87. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with isolated showers. Lows 67 to 77. Northeast winds 10 to 15 mph decreasing to up to 10 mph after midnight. Chance of rain 20 percent.

Monday: 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.

Detailed Forecast

Synopsis

Trade winds will strengthen slightly into the moderate to locally breezy range through Wednesday. Mostly dry and stable trade wind weather conditions will prevail through the next seven days. The next best chance for increasing shower trends across the Hawaiian Islands may develop by next weekend as a weak wave in the easterlies marches down the island chain.

Discussion

Fairly stable stratocumulus clouds, as shown on infra-red satellite imagery are moving into the Hawaiian Islands on the easterly trade winds this morning. Local radar imagery continues to show mostly isolated to scattered shower coverage through the overnight to early morning hours. Wind observations at over the Mauna Kea summit on the Big Island this morning remain below wind advisory thresholds. This summit level advisory was cancelled with this morning's forecast package.
Stable weather trends will likely continue through Friday as the upper level ridge remains anchored over the Hawaiian Islands, limiting vertical cloud heights and shower development. Looking out into the extended range forecast, the next best chance for increasing shower trends will develop from Saturday into early next week as a weak wave in the easterlies marches from east to west down the island chain.
Trade wind speeds may increase slightly into the moderate to locally breezy range through Wednesday, as the surface ridge axis drifts north and a weak disturbance in the deep tropics passes far south of the island chain; increasing the surface pressure gradients over the Hawaii Region.

Aviation

Light to moderate trade winds will intensify to moderate to locally breezy in the afternoon. Breezy conditions are expected to persist through at least mid-week. Bands of light showers moving in off the Pacific will favor windward slopes and coasts. Isolated spillover showers are to be expected across leeward portions of the smaller islands, especially in the late night and morning hours. On the Big Island, afternoon and early evening cumulus build-ups may yield moderate showers along south and west facing slopes.
AIRMET Sierra is currently in effect for mountain obscuration along north and east facing slopes of all islands. Conditions are expected to improve shortly after sunrise across the smaller islands, but could linger into mid-afternoon across windward Big Island.
AIRMET Tango remains in effect for moderate mid-level turbulence over and immediately south through southwest of Big Island Summits. Summit level winds have intensified due to strengthening high pressure far north of the islands. Conditions will likely persist for the next 24 hours.

Marine

The surface ridge N of the islands remains suppressed southward from its climatological norm, due to complex low pressure filling a large portion of the central N Pacific. Trade wind speeds are therefore somewhat lighter than seasonal normals, especially over the N end of the chain, but will trend stronger through Monday as the ridge builds northward. Moderate to locally strong E trade winds are then expected to persist through at least Thursday, and a Small Craft Advisory is now posted for most waters around Maui and the Big Island.
Offshore buoys show that the moderate-period (~14 seconds) S swell of the past couple days is slowly trending down as it becomes SSE, but near shore PacIOOS buoys indicate that elevated surf will remain in place today, with a slow trend down thereafter. Another, similarly-sized SSW swell appears poised to arrive by next weekend.
The aforementioned complex low N of Hawaii will deliver a small, short-period (10 seconds) NNW swell that will build today, peak Monday, and diminish Tuesday. PacIOOS Hanalei buoy is showing increasing energy from the NNW in the 10-14 second bands this morning. Another small NNW swell may arrive later in the week. Surf along E facing shores will remain relatively small while trending up slightly the next couple of days due to increased trades. Small, long-period E swells from increased E Pacific tropical cyclone activity may arrive from Wednesday onward.
New moon high tides combined with higher-than-predicted water levels will lead to minor coastal flooding this afternoon, with details contained in the Coastal Hazard Message (CFWHFO).

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov