West Side

Today: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 84. East winds up to 15 mph. Chance of rain 30 percent.

Tonight: Partly cloudy with isolated showers. Lows 70 to 76. East winds up to 15 mph. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers. Highs around 84. East winds up to 15 mph. Chance of rain 20 percent.

South Side

Today: Mostly sunny with isolated showers. Highs around 89. North winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers after midnight. Lows 70 to 77. North winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Monday: Sunny. Isolated showers in the morning. Highs around 89. Light winds becoming north up to 15 mph in the afternoon. Chance of rain 20 percent.

North Shore

Today: Breezy. Partly sunny with scattered showers. Highs 80 to 86 near the shore to around 68 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Scattered showers. Lows around 73 near the shore to around 54 near 5000 feet. East winds up to 20 mph shifting to the southeast 10 to 15 mph after midnight. Chance of rain 50 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 80 to 86 near the shore to around 68 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Central Maui

Today: Breezy. Mostly sunny with isolated showers. Highs 83 to 90. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers after midnight. Lows around 72. East winds up to 20 mph decreasing to up to 10 mph after midnight. Chance of rain 20 percent.

Monday: Mostly sunny. Isolated showers in the morning. Highs 83 to 90. Northeast winds up to 15 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny with scattered showers. Highs around 64 at the visitor center to around 68 at the summit. Southeast winds up to 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows around 51 at the visitor center to around 47 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

Monday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 66 at the visitor center to around 69 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

East Maui

Today: Breezy. Partly sunny with scattered showers. Highs 80 to 86 near the shore to around 68 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Breezy. Scattered showers. Lows around 73 near the shore to around 54 near 5000 feet. East winds up to 20 mph shifting to the southeast 10 to 15 mph after midnight. Chance of rain 50 percent.

Monday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 80 to 86 near the shore to around 68 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Lanai City

Today: Mostly sunny with isolated showers. Highs 74 to 83. Northwest winds up to 10 mph shifting to the northeast in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 67. Northeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers. Highs 74 to 83. East winds up to 10 mph. Chance of rain 20 percent.

Kaunakakai

Today: Breezy. Mostly sunny with isolated showers. Highs 74 to 90. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly clear with isolated showers. Lows 62 to 76. East winds 10 to 20 mph. Chance of rain 20 percent.

Monday: Sunny. Isolated showers in the morning. Highs 73 to 90. East winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Weak low pressure far northwest of the islands will move further off to the west as high pressure expands over the Central Pacific. Greater lower to mid layer moisture will thin out as drier air moves in from the east the next few days. Coastal and higher terrain trades will generally remain moderate with locally strong winds through the middle of the week. Showers will become less frequent and focus along windward upslope mauka exposures.

Discussion

The influence of a passing mid level trough across the western third of the island chain, along with weak upper low north churning near 35N165W, within a lingering moisture rich air resident mass provided enough instability to develop overnight Oahu plume and northern moving rain that trained over the Garden Island. The heaviest rain fell parallel to Kauai's high ridgelines with half an inch to inch hourly rates lifting local streams downstream of Mount Waialeale (Wainiha) to flood stage. The trajectory of the precipitation south of Kauai is now sliding a touch more west and away from Kauai thus lessening the morning threat. Many higher elevation regions within central and northern Kauai picked up about one to two inches since last night with neighboring Oahu receiving a few tenths an inch more rain within the Manoa and Nuuanu Valleys since yesterday evening. A drier air mass moving in from the east will suppress widespread rain with widely scattered light showers sticking to windward exposed upslope mauka through the week. This drier week will likely exacerbate short term fire weather conditions as the state will fall deeper into abnormally dry to moderate drought categories (see Fire Weather section below). Surface high pressure far north northeast of the state will continue to produce a gradient tight enough to drive moderate to locally strong trade winds over the islands for the next few days.
Lowering heights slinking away to the northwest, as ridging at all levels takes hold from the south and east, will ensure a more stable environment for the week to come. The dry air has yet to arrive as Hilo's 12Z sounding is showing a saturated layer up to 800 mb (7 k ft) within a very moist air mass of near 1.75 inch pwats which is in the lower 10% of climatological occurrence. Upper ridging will anchor itself over the southern latitudes and will directly influence late July drier island weather. The approach of a shortwave mid level trough from the east at mid week may subtly weaken winds but limited moisture will maintain statewide low rain chances. The drier trend is supported by the both ensembles where the majority of the members keep the diurnal periods of higher QPF either north or south of the island archipelago. Slightly weaker synoptic trade flow may allow local breezes to take over and create their own micro-climates (e.g., afternoon Big Island kona slope sea breeze showers).

Marine

A trough passing westward near Kauai will allow the high pressure to build back into the region and strengthen trade winds into the moderate to locally strong range into the middle of next week.
Several pulses of southerly and southwesterly swell will continue to boost surf heights along south and some of the west facing shores this week.
Surf along east facing shores will remain small and choppy. Surf along north facing shores will remain nearly flat through the forecast period.
Peak high tides associated with the lunar cycle could lead to minor coastal flooding along shorelines and low-lying coastal areas next week Monday through Wednesday during the daily peak tide each afternoon.

Fire weather

Due to recent rain, statewide fire weather concerns will remain low to begin the week. Drier conditions this week will begin to awaken a heightened situational awareness to the increased wildfire threat. KDBI values exceeding 600 with afternoon humidities falling into the lower to mid 50s under lighter interior winds should hold the near to medium term fire threat at bay.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov