Photo Credit: Tyler Rooke

West Side

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 74 to 83. East winds 20 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 66 to 72. Northeast winds 20 to 25 mph. Chance of rain 50 percent.

Tuesday: Partly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 74 to 83. Northeast winds 15 to 20 mph. Chance of rain 40 percent.

South Side

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs around 85. North winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 65 to 72. North winds 10 to 20 mph. Chance of rain 20 percent.

Tuesday: Breezy. Mostly sunny with isolated showers. Highs around 85. North winds 10 to 20 mph. Chance of rain 20 percent.

North Shore

Today: Breezy. Occasional showers in the morning, then partly sunny with showers likely in the afternoon. Highs 74 to 80 near the shore to around 63 near 5000 feet. East winds 10 to 20 mph. Chance of rain near 100 percent.

Tonight: Mostly cloudy. Breezy. Showers likely in the evening, then occasional showers after midnight. Lows around 69 near the shore to 48 to 54 near 5000 feet. East winds 10 to 20 mph. Chance of rain 90 percent.

Tuesday: Mostly cloudy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 73 to 80 near the shore to around 64 near 5000 feet. East winds 10 to 15 mph. Chance of rain 90 percent.

Central Maui

Today: Breezy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 79 to 84. Northeast winds 15 to 20 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 65 to 70. Northeast winds around 15 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 79 to 85. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Upcountry

Today: Breezy. Mostly sunny with scattered showers. Highs around 58 at the visitor center to around 54 at the summit. East winds 15 to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Partly cloudy with scattered showers. Lows around 47 at the visitor center to around 44 at the summit. East winds 15 to 25 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 59 at the visitor center to around 54 at the summit. East winds 15 to 25 mph. Chance of rain 50 percent.

East Maui

Today: Breezy. Occasional showers in the morning, then partly sunny with showers likely in the afternoon. Highs 74 to 80 near the shore to around 63 near 5000 feet. East winds 10 to 20 mph. Chance of rain near 100 percent.

Tonight: Mostly cloudy. Breezy. Showers likely in the evening, then occasional showers after midnight. Lows around 69 near the shore to 48 to 54 near 5000 feet. East winds 10 to 20 mph. Chance of rain 90 percent.

Tuesday: Mostly cloudy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 73 to 80 near the shore to around 64 near 5000 feet. East winds 10 to 15 mph. Chance of rain 90 percent.

Lanai City

Today: Breezy. Mostly sunny with isolated showers. Highs 71 to 79. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening, then scattered showers after midnight. Lows around 64. Northeast winds 15 to 20 mph. Chance of rain 30 percent.

Tuesday: Breezy. Mostly sunny with isolated showers. Highs 71 to 79. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Kaunakakai

Today: Breezy. Mostly sunny with isolated showers. Highs 65 to 84. East winds 15 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 57 to 72. East winds 15 to 20 mph. Chance of rain 20 percent.

Tuesday: Breezy. Mostly sunny with isolated showers. Highs 65 to 84. East winds 10 to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Blustery trade winds will persist into the middle of the week, with lighter trade winds expected toward the end of the week. Passing showers will favor windward and mountain areas. Increased moisture tonight into Wednesday will lead to higher trade shower coverage and intensity. As our airmass becomes more unstable, some showers may be briefly heavy. After a bit of a break Thursday and Friday, moisture may increase again next weekend.

Discussion

Forecast philosophy for the next five days has not changed from last evening, but forecast uncertainty remains high for next weekend and beyond. High pressure far north of the islands will move southeastward and gradually weaken through the middle of the week, leaving a ridge to our north. Expect breezy to strong trade winds through mid-week due to the tight pressure gradient south of the high. Models show lighter winds Thursday into Friday as a front northwest of the islands weakens the ridge. Satellite loop shows a ragged band of showery low clouds over the smaller islands and across windward portions of the Big Island, fueling increased windward showers. The Big Island looks to remain relatively dry, at least this morning. The leading edge of a frontal cloud band is about 300 miles northeast of the islands. This cloud band will move in tonight into Wednesday, fueling another increase in showers as well as a surge in trade wind speeds. This cloud band may remain over the area through Wednesday night and could potentially arrive over windward Big Island as early as this afternoon.
An upper trough is forecast to move over the islands tonight, then linger for several days, marginally destabilizing our airmass. Brief heavy showers may develop, especially as the frontal band arrives. However, showers will push quickly westward within the trades, reducing the potential for flooding rainfall. Summit temperatures will likely drop below freezing on the Big Island, but moisture depth will be somewhat limited. Wintry precipitation on the summits will most likely fall as freezing rain. This may necessitate issuance of a Winter Weather Advisory.
Forecast confidence beyond Friday is low as models disagree on how to handle development of a low forecast to form west to northwest of the islands over the weekend. ECMWF wants to develop this low to our west with little rainfall impact to the islands, while GFS develops the low to our northwest with pronounced rainfall impacts.

Aviation

High pressure north of the state will continue to generate breezy to locally windy trade winds across the islands over the next several days. A band of clouds and showers moving in with the trades stretches from Molokai to the Big Island this evening. AIRMET Sierra is posted for tempo mountain obscurations over windward portions of these islands, which will likely continue through the morning before departing to the south and west. VFR conditions will prevail elsewhere with isolated mountain obscurations. Another band of clouds and showers will arrive from the north tonight.
AIRMET TANGO remains in effect below 7000 feet over and immediately south through west of all mountains due to low-level, mechanical turbulence provided by the breezy trades.

Marine

A large 1032 mb surface high north of the region will continue to drift southeast and slowly weaken over the next few days. Fresh to strong easterly trade winds remain in the forecast through Wednesday as a weakening cold front drifts into the islands from the north. Expect increasing cloud and shower trends in the short term as the frontal cloud band slowly moves through the region with enhanced showers lingering into Wednesday. A stronger cold front will also move into the region from the northwest on Wednesday, gradually weakening the ridge north of the Hawaiian Islands. Trade wind speeds will decrease into the moderate to fresh range from Thursday onward.
The Small Craft Advisory (SCA) remains in effect for all Hawaiian waters through 6 PM HST Tuesday, due to a combination of strong winds and seas. Strong winds and wave heights will lower from late Wednesday into the weekend, decreasing the threat for SCA conditions across the region.
Surf along north facing shores will trend higher starting this morning as a moderate size, medium to long period north northeast swell arrives. Buoy 51101 is already reporting increasing swell heights from a northerly direction. This swell will increase surf along north and west facing shores through Wednesday before fading away from Wednesday night into Thursday. Surf heights will flirt with Surf Advisory levels along north facing shores on Tuesday and Wednesday. The next northwest swell will boost surf heights across the islands arriving on Friday with surf heights trending higher for all north and west facing shores. The new northwest swell will peak on Saturday, and last through Sunday. East facing shores will see rough choppy surf through Wednesday with some wrap around energy from the northerly swell. Expect decreasing wave heights as the trade wind speeds drop from Thursday onward. Surf heights along south facing shores will remain nearly flat this week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Tuesday for all Hawaiian waters,

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Data Courtesy of NOAA.gov