West Side

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 80 to 85. Northeast winds up to 10 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 68 to 76. Light winds. Chance of rain 40 percent.

Tuesday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Haze in the afternoon. Highs around 83. Light winds. Chance of rain 30 percent.

South Side

Today: Mostly sunny with isolated showers. Highs around 87. North winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 68 to 77. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny. Isolated showers in the afternoon. Haze in the afternoon. Highs around 88. Light winds becoming southwest up to 10 mph in the afternoon. Chance of rain 20 percent.

North Shore

Today: Mostly sunny with isolated showers. Highs 80 to 85 near the shore to around 66 near 5000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 72 near the shore to 50 to 55 near 5000 feet. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 80 to 85 near the shore to around 66 near 5000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Central Maui

Today: Mostly sunny with isolated showers. Highs 81 to 88. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 69 to 74. East winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 82 to 89. Light winds. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 62 at the visitor center to around 66 at the summit. Northeast winds up to 10 mph in the morning becoming light. Chance of rain 50 percent.

Tonight: Partly cloudy. Scattered showers in the evening. Lows around 49 at the visitor center to around 43 at the summit. Light winds. Chance of rain 30 percent.

Tuesday: Sunny. Isolated showers in the afternoon. Haze in the afternoon. Highs around 62 at the visitor center to around 65 at the summit. Light winds. Chance of rain 20 percent.

East Maui

Today: Mostly sunny with isolated showers. Highs 80 to 85 near the shore to around 66 near 5000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 72 near the shore to 50 to 55 near 5000 feet. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers. Highs 80 to 85 near the shore to around 66 near 5000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Lanai City

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 73 to 81. Northeast winds up to 10 mph in the morning becoming light. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 67. Light winds. Chance of rain 50 percent.

Tuesday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Haze in the afternoon. Highs 73 to 81. Southeast winds up to 10 mph. Chance of rain 30 percent.

Kaunakakai

Today: Partly sunny with scattered showers. Highs 73 to 88. Northeast winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 60 to 74. Light winds. Chance of rain 40 percent.

Tuesday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 74 to 89. Light winds. Chance of rain 40 percent.

Detailed Forecast

Synopsis

A band of embedded showers are being escorted by a trough just north of the Hawaiian Islands this morning, bringing periods of isolated showers to Kauai and Oahu today. Winds will weaken and become more southeasterly, leading to the development of a land and sea breeze regime, persisting through Thursday. Thereafter, moderate trades return at the end of the week.

Discussion

Latest satellite imagery continues to show an unambiguous band of embedded showers escorted by a north to south propagating trough just north of the Hawaiian Islands. Model guidance of the GFS and ECMWF has done a fairly decent job identifying this trough, portraying isolated shower activity descending upon Kauai early this morning and is progged to extend further southward into Oahu shortly thereafter before dissipating. An uptick in shower activity has been presented over Kauai and dialed down over Oahu as this feature passes southward, but given the quick nature of the trough and its weakening status, anticipated rainfall accumulations are expected to be minimal. That said, a clear-cut mid-level low near 29N 150W as of 0300 HST (13z), where towering cumulus and heavier showers are being observed well northeast of the islands are expected to keep distance away from the islands, and not impactful to Hawaiian weather today.
A secondary trough, slightly weaker in composition, extends southeastward from the aforementioned mid-level low and is slowly meandering westward. Winds across the Hawaiian Islands have noticeably eased in response of each passing trough, progged to veer east-southeasterly, resulting in a more pronounced land and sea breeze regime lasting through early Thursday. In such a pattern where the local scale winds are virtually absent, island heating will support sea breezes during the day, which will enhance leeward and interior shower activity, and overnight cooling will drive land breezes at night, clearing the night skies and limiting showers.
Light to moderate trades begin to reestablish late Thursday with the introduction of a strong high pressure ridge axis building in far to the northeast of the region. Latest model guidance suggests this pressure ridge will slowly migrate southward toward the middle of next weekend, indicative of moderate trades across much of the state during this time. There is a bit of uncertainty in the forecast for the latter half of the week, however, as some deterministic model guidance is hinting at another surface trough developing just north of the Hawaiian Islands late this week, which would disrupt winds and increase shower activity. Confidence remains low concerning the exact timing and placement, or whether the feature will develop.

Aviation

Light to moderate northerly winds are pushing a band of low level clouds with embedded showers over Kauai early this morning. This band is expected to push over Oahu during morning commute hours and dissipate over the island through the afternoon. AIRMET Sierra is currently in effect for mtn obsc over N to SE sections of Kauai as this band of showers drifts south generating periods of MVFR conditions. AIRMET Sierra may need to be expanded for Oahu as this band continues to drift south and settle over the island later this morning and afternoon.
Winds are expected to weaken a notch this afternoon and veer more southerly as the trough weakens and retrogrades west and other trough deepens east of the state. Expect afternoon seabreeze conditions will develop each afternoon generating periods of MVFR conditions over sheltered leeward and interior locations. Land breeze will develop overnight with conditions improving to mostly VFR conditions. This pattern is expected to repeat over the next couple of days.

Marine

A trough over the northwest coastal waters is moving southeast and will move over Kauai this morning. As the trough moves over Kauai, scattered showers are expected along the trough with moderate northeast trade winds filling in over Kauai waters, while elsewhere gentle to locally moderate easterly trade winds are expected through tonight. Another trough northeast of the offshore waters will slowly drift west over the next few days. Tuesday through Thursday light to gentle southeast flow across all zones are expected and will also give way to localized land and sea breezes. Moderate trades will fill in from east to west at the end of the weak as high pressure builds far northeast and drifts southeast.
The current moderate north-northwest swell that peaked well above High Surf Advisory (HSA) levels Sunday has begun to decline quickly overnight and will continue to decline today. Also, a small medium to long period northwest (320 deg) swell is expected to fill in this afternoon, peak tonight and slowly decline Tuesday. No significant north swells are expected through the week except the potential for a moderate medium to long period northwest (320 deg) swell Sunday into early next week.
A small, long- period southwest swell has started to fill in overnight with long period 16 second forerunners. The swell is expected to peak today before subsiding Tuesday. Another small long- period southwest (200 deg) swell is possible by the later half of the week. Surf along east- facing shores will remain below average through the week except for select shorelines exposed to the current north swell today.
Peak high tides associated with the lunar cycle will lead to minor coastal flooding along shorelines and low lying coastal areas starting Tuesday through the weekend. Coastal flooding will coincide with the daily peak tide each afternoon.

Fire weather

Light winds and increased showers will help maintain below critical fire weather thresholds for the next several days. Temperature inversion heights across the state will range from 7000 to 8000 feet through tonight.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov