West Side

Today: Sunny. Highs around 77. Southeast winds up to 10 mph shifting to the southwest in the afternoon.

Tonight: Partly cloudy. Lows 63 to 69. Light winds.

Tuesday: Mostly sunny. Highs 75 to 80. Light winds.

South Side

Today: Sunny. Highs around 82. Light winds.

Tonight: Partly cloudy. Lows 61 to 71. Light winds.

Tuesday: Mostly sunny. Highs around 81. Light winds.

North Shore

Today: Breezy. Mostly sunny with isolated showers. Highs around 78 near the shore to around 63 near 5000 feet. Southeast winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 67 near the shore to around 47 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers in the morning, then partly sunny in the afternoon. Highs around 78 near the shore to around 63 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Central Maui

Today: Sunny. Highs around 81. East winds up to 15 mph.

Tonight: Partly cloudy. Lows around 64. South winds up to 10 mph in the evening becoming light.

Tuesday: Mostly sunny. Highs around 81. Light winds.

Upcountry

Today: Mostly sunny with isolated showers. Highs around 59 at the visitor center to around 67 at the summit. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Lows around 43 at the visitor center to around 45 at the summit. East winds up to 10 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers in the morning, then partly sunny in the afternoon. Highs around 58 at the visitor center to around 65 at the summit. Light winds. Chance of rain 20 percent.

East Maui

Today: Breezy. Mostly sunny with isolated showers. Highs around 78 near the shore to around 63 near 5000 feet. Southeast winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 67 near the shore to around 47 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers in the morning, then partly sunny in the afternoon. Highs around 78 near the shore to around 63 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Lanai City

Today: Mostly sunny. Highs 69 to 76. Light winds.

Tonight: Mostly clear. Lows around 62. Light winds.

Tuesday: Mostly sunny. Isolated showers in the morning. Highs 68 to 76. Light winds. Chance of rain 20 percent.

Kaunakakai

Today: Mostly sunny with isolated showers. Highs 66 to 82. Southeast winds 10 to 15 mph shifting to the south in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 53 to 69. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny. Highs 66 to 82. Light winds.

Detailed Forecast

Synopsis

Southeast low level winds will bring increasing temperatures and humidity, and light showers (mainly windward and mauka) through Tuesday. A front will move into the western end of the state Tuesday night. Increased moisture will linger for several days; possibly all the way into the weekend. Flooding risk is small but worth mentioning as we await clarity in the long range models.

Discussion

Radar has been indicating light showers overnight, mainly on the southeast side of Big Island but also a few light showers spread over pretty much all of the islands. Satellite continues to show mostly cloudy skies as low level clouds move in from the southeast and high level clouds move in from the northwest.
Low level winds have veered around to southeast as expected, and this will bring warmer and more moist air into the region. Winds will continue to veer through Tuesday, leading to progressively warmer and more humid conditions. They will become light enough to allow for a sea- and land-breeze pattern in some areas later today and Tuesday. A cold front will approach Kauai County Tuesday night, likely passing through around midnight.
Latest guidance is still showing a variety of solutions on timing and extent of the eastward movement of the front. Latest best guess is that it will stall near Oahu Wednesday afternoon. Thursday and Friday, there are roughly equal chances that the front then gets pushed to near the Big Island, or alternatively pulls back west toward Kauai. Either way, moisture will increase over the state and the chance of rain increases over all islands. This has as much to do with increasing moisture coming in on southeast low level flow over the eastern part of the state as it does moisture from the front itself.
NBM PoPs seem too low considering the above, and were not closely followed this morning. Models also indicate that the extensive moisture could well remain over the state all the way through the coming weekend, and PoPs were increased accordingly. Overall, it will be a return to a wetter and warmer pattern. There is a small risk of thunderstorms, heavy rain, and flooding, but details are still too murky to be confident in specific timing/location.

Aviation

Moderate east-southeasterly winds will prevail during the next 24 hours, with terrain sheltering effects becoming dominant and allowing for land and sea breezes to develop across much of the state. Rather dry conditions will persist with a few light showers possible at times, mainly over windward and slopes and coasts. VFR conditions are expected to prevail at all TAF sites.
No AIRMETs are in effect and none are anticipated today.

Marine

The morning package has the Small Craft Advisory (SCA) trimmed back to the typical windier waters near Maui County and the Big Island through tonight. Winds are on the decline, but an overnight ASCAT pass show winds remaining at SCA levels in these areas, and the high resolution models show the winds lingering in these areas into tonight. Seas however have fallen below SCA levels. The swell responsible for the SCA seas, and the High Surf Advisory (HSA) is on the decline, and the resultant surf has fallen below HSA levels. As a result, the HSA for the north and west facing shores has been cancelled.
Winds will continue to weaken through tonight as a cold front approaches the islands from the northwest. The front is expected to enter the northwest offshore waters tonight, and reach the coastal waters northwest of Kauai Tuesday night. Isolated thunderstorms over the northwest offshore waters are possible with the front's arrival. The front will weaken as it enters the coastal waters, and is expected to stall out over central coastal waters Wednesday into Thursday.
The current northwest swell will continue to subside today. As mentioned above, the resultant surf has fallen below HSA levels. Another moderate, long period, northwest swell is expected to arrive in the islands Tuesday, and linger into the middle of the week, and slowly subside during the end of the week. This swell will maintain elevated surf near advisory levels along north and west facing shores.
There are no noteworthy swells for the next few days for east and south facing shores.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov