Photo Credit: Travis Guthrie

West Side

Today: Mostly cloudy in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs 74 to 80. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 62 to 69. East winds 10 to 20 mph. Chance of rain 50 percent.

Tuesday: Breezy. Partly sunny with isolated showers. Highs 76 to 82. East winds 10 to 20 mph. Chance of rain 20 percent.

South Side

Today: Mostly cloudy in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 80. North winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy after midnight. Lows around 63. North winds up to 15 mph. Chance of rain 20 percent.

Tuesday: Partly sunny. Highs around 82. Northeast winds up to 15 mph.

North Shore

Today: Breezy. Mostly cloudy with showers likely. Highs 72 to 77 near the shore to around 56 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with showers likely. Lows 60 to 66 near the shore to 44 to 49 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Tuesday: Breezy. Mostly cloudy with scattered showers. Highs 74 to 79 near the shore to around 57 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Central Maui

Today: Mostly cloudy in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs 76 to 81. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows 61 to 66. East winds 10 to 20 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.

Tuesday: Breezy. Partly sunny with isolated showers. Highs 78 to 83. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Upcountry

Today: Mostly cloudy with scattered rain showers in the morning, then mostly sunny with isolated rain showers in the afternoon. Highs around 50 at the visitor center to around 45 at the summit. East winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered rain showers. Lows around 41 at the visitor center to around 35 at the summit. East winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Partly sunny. Scattered rain showers in the morning, then isolated rain showers in the afternoon. Highs around 51 at the visitor center to around 46 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

East Maui

Today: Breezy. Mostly cloudy with showers likely. Highs 72 to 77 near the shore to around 56 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with showers likely. Lows 60 to 66 near the shore to 44 to 49 near 5000 feet. East winds 10 to 25 mph. Chance of rain 70 percent.

Tuesday: Breezy. Mostly cloudy with scattered showers. Highs 74 to 79 near the shore to around 57 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Lanai City

Today: Mostly cloudy in the morning, then mostly sunny with scattered showers in the afternoon. Highs 70 to 77. Northeast winds up to 15 mph. Chance of rain 30 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Lows around 62. Northeast winds up to 10 mph.

Tuesday: Partly sunny. Isolated showers in the afternoon. Highs 71 to 78. East winds up to 15 mph. Chance of rain 20 percent.

Kaunakakai

Today: Mostly cloudy in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs 69 to 79. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 57 to 69. East winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday: Breezy. Partly sunny with isolated showers. Highs 70 to 80. East winds 10 to 15 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate to breezy trade winds will continue through the middle of the week, delivering showery low clouds to windward and mauka areas, with a few showers spreading to leeward communities as well. High clouds will continue to stream overhead during the next several days, bringing considerable cloudiness at times. The potential for unsettled weather increases from Thursday through the weekend, with southeast winds bringing periods of moderate to heavy rain.

Discussion

Currently at the surface, a broad area of low pressure is located around 800 miles west-northwest of the state, with a weakening nearly stationary front well to the east of the low, roughly 250 miles west of Kauai. Meanwhile, a strong 1041 mb high is centered around 1650 miles north of Honolulu. The high remains the dominant weather feature locally, and is driving moderate to locally breezy trade winds across the island chain early this morning. Infrared satellite imagery shows considerable mid and high level cloud cover over the state, resulting in mostly cloudy conditions. Radar imagery shows scattered showers moving into windward areas, with a few showers occasionally spilling over into leeward communities. Main short term concerns continue to revolve around rain chances and trade wind trends.
The stationary front to the west of the state is expected to weaken into a trough and shift slowly west-southwestward today through Wednesday. Meanwhile, strong high pressure to the distant north will remain nearly stationary during this time, allowing moderate to locally breezy trade winds to persist, and potentially linger into the day Thursday. Model solutions are in relatively good agreement showing an area of low pressure developing along 170W late Thursday and Thursday night, with the low then lifting northward and eventually northwestward Friday through the weekend, while the strong high north of the state weakens and shifts southeast. As a result, winds are forecast to shift around to the southeast at moderate speeds Thursday night and Friday, with moderate southerly winds following over the weekend.
As for the remaining weather details, we should see a fairly typical trade wind shower regime hold in place through the middle of the week, with showers favoring windward and mauka areas, particularly at night and during the morning hours. With moderate to breezy trades holding in place, showers will reach leeward communities at times as well. Meanwhile, with troughing aloft to the west of the state, scattered to broken high clouds will stream over the islands, bringing periods of considerable cloudiness during the next several days. Model solutions have come into better agreement Thursday through the weekend, with unsettled weather looking more likely. With winds swinging around to the southeast and south, we should see a confluence of deep moisture advecting in from the east and lifting northward from the Intertropical Convergence Zone. The result appears to be an extended period of wet weather, with moderate to heavy rainfall impacting the island chain at times. Considerable cloud cover looks likely through the period and there remains the potential for some more snow on the Big Island summits as well.

Aviation

Low cloudiness and showers will affect windward and mauka sections across the state as breezy trade winds persist in response to a strong high centered far north of the islands. AIRMET Tango is posted for tempo moderate turbulence below 8000 feet for areas south through west of island terrain. AIRMET Tango is also posted for tempo moderate turbulence in layer 140-FL240 over Kauai and Oahu due to an upper low northwest of the state. Light icing will also be possible across Kauai in the layered cloud cover associated with the low.
AIRMET Sierra is posted for tempo mountain obscurations over north through east portions of Kauai and Oahu. Showers may fill in a bit more tonight with AIRMET Sierra possible along other windward slopes.

Marine

A well anchored surface high located far north of the islands will keep fresh to strong trade winds through Wednesday, then mainly moderate speed during the second half of the week while the trade winds begin to shift to the southeast across the smaller islands starting about Thursday afternoon. This is in response to a developing and intensifying surface low northwest of Kauai.
A Small Craft Advisory (SCA) covers a good part of the near-shore waters due not only to strong trade winds but also seas of 10 feet or higher, from contribution from a north-northeast swell. The strong trade winds are concentrated over the windward waters and waters around Kauai in response to a low pressure system west of the offshore waters. This low will also maintain a chance of thunderstorms over the western and southern offshore waters through much of the week. Water conditions will be very rough and choppy through Tuesday.
A series of west-northwest swells are expected this week, with the largest expected to arrive today. So far, this swell has not appeared at both buoy 51101 or the Hanalei buoy, yet. We expect this swell to arrive tonight and Tuesday at a smaller scale. But a combination of moderate to strong trades and a north-northeast swell pulse will put surf near but slightly below the advisory criteria of 10 feet for the east facing shores of Kauai and Oahu today. Guidance suggests the swell will ease slightly Tuesday, thus expect surf along east facing shores of Kauai and Oahu to be at a moderate range. Exposed east facing shores of the remaining islands will be at a moderate range through Tuesday. Weaker trades during the second half of the week, along with a smaller northeast swell equates to small to moderate surf along the east facing shores during the second half of the week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Tuesday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Kaiwi Channel, Maui County Windward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov