Photo Credit: Tyler Rooke

West Side

Today: Breezy. Mostly cloudy with isolated showers. Highs 77 to 84. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 62 to 68. East winds 10 to 20 mph. Chance of rain 40 percent.

Tuesday: Mostly cloudy with scattered showers. Highs 77 to 84. East winds up to 15 mph. Chance of rain 50 percent.

South Side

Today: Mostly cloudy. Highs around 83. North winds up to 15 mph.

Tonight: Mostly cloudy. Isolated showers in the evening. Lows around 63. Northwest winds up to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly cloudy. Scattered showers in the afternoon. Highs around 83. Northwest winds up to 10 mph. Chance of rain 50 percent.

North Shore

Today: Breezy. Mostly cloudy with scattered showers. Highs 74 to 81 near the shore to around 62 near 5000 feet. East winds up to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with showers likely. Lows 60 to 66 near the shore to around 50 near 5000 feet. East winds up to 20 mph shifting to the southeast 10 to 15 mph after midnight. Chance of rain 70 percent.

Tuesday: Mostly cloudy. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 74 to 81 near the shore to around 60 near 5000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Central Maui

Today: Breezy. Mostly cloudy with isolated showers. Highs 79 to 84. East winds 10 to 25 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: Mostly cloudy. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 79 to 84. East winds up to 20 mph. Chance of rain 50 percent.

Upcountry

Today: Mostly cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 55 at the visitor center to around 52 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 44 at the visitor center to around 41 at the summit. Northeast winds up to 10 mph. Chance of rain 50 percent.

Tuesday: Mostly cloudy. Scattered showers in the morning, then showers likely in the afternoon. Highs around 53 at the visitor center to around 49 at the summit. East winds up to 10 mph in the morning becoming light. Chance of rain 70 percent.

East Maui

Today: Breezy. Mostly cloudy with scattered showers. Highs 74 to 81 near the shore to around 62 near 5000 feet. East winds up to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with showers likely. Lows 60 to 66 near the shore to around 50 near 5000 feet. East winds up to 20 mph shifting to the southeast 10 to 15 mph after midnight. Chance of rain 70 percent.

Tuesday: Mostly cloudy. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 74 to 81 near the shore to around 60 near 5000 feet. East winds up to 20 mph. Chance of rain 70 percent.

Lanai City

Today: Mostly cloudy. Isolated showers in the afternoon. Highs 72 to 79. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with isolated showers. Lows around 64. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tuesday: Mostly cloudy. Isolated showers in the morning, then showers likely in the afternoon. Highs 72 to 79. North winds up to 15 mph. Chance of rain 70 percent.

Kaunakakai

Today: Mostly cloudy. Breezy. Isolated showers in the afternoon. Highs 74 to 82. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly cloudy with isolated showers. Lows 60 to 69. East winds 10 to 20 mph. Chance of rain 20 percent.

Tuesday: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 74 to 82. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Breezy trade winds will prevail today, with rather dry trade wind weather, and increasing high clouds streaming into the island chain. The trades will ease tonight into early Wednesday, with trade showers increasing and considerable cloudiness holding in place as an upper level disturbance moves overhead. Decreasing clouds and a return to more typical trade wind weather can be expected late Wednesday through Thursday night, with the trades becoming breezy once again. The trades are forecast to ease slightly Friday through the weekend, with showers continuing to favor windward and mauka areas.

Discussion

Currently at the surface, a 1028 mb high is centered around 900 miles northeast of Honolulu, while a cold front is positioned 1050 miles northwest of Kauai. The gradient remains tight, but has relaxed slightly overnight, with breezy trade winds prevailing across the island chain early this morning. Infrared satellite imagery shows abundant high cloud cover resulting in mostly cloudy conditions across the state. Radar imagery shows a few showers moving into windward areas, with mainly dry conditions in leeward areas. Main short term focus revolves around trade wind trends and rain chances during the next few days.
High pressure north of the state will slide east-northeast during the next few days as a cold front steadily approaches from the northwest. Breezy trades will prevail today, then ease to moderate levels tonight through early Wednesday. The trades will then ramp back up to breezy levels late Wednesday through Thursday night as the front stalls out a couple hundred miles north of Kauai, and a new 1030+ mb high builds eastward along 35N. More forecast uncertainty develops Friday through the weekend as the wind forecast will be highly dependent on how much the low level flow tips to the east-southeast in advance of a new cold front approaching from the northwest. Overall, we should see an easing of the trades into the moderate to locally breezy range during this time. The strongest trades appear to remain near the Big Island, while some sheltering effects could allow for land and sea breezes over leeward sections of the smaller islands.
As for the remaining weather details, drier than normal trade wind weather should prevail today, with showers mainly affecting windward areas. Shortwave energy will then slide northward over the islands tonight through Wednesday while we see some entrance and exit region forcing from a pair of upper level jets to the north and south of the state respectively. Precipitable water values also climb into the 1.5 to 1.7 inch range highest from Oahu eastward. These factors should bring an increase in trade wind shower coverage and intensity, and allow a few more showers to reach leeward areas as well. Additionally, considerable high cloud cover will prevail through Tuesday night, particularly over the eastern end of the state. The upper level forcing for ascent will slide east of the state by Wednesday night, while deeper moisture pushes south of the island chain. This should bring a more typical trade wind shower regime back to the islands Wednesday night through Thursday night, although it may be a bit more showery over the eastern islands than the western end of the state.
As with the wind forecast, more uncertainty develops Friday through the upcoming weekend. The 00z and 06z GFS runs advertise a wet east-southeasterly flow pattern developing, while the 03/12z and 04/00z runs of the ECMWF keep more of a normal trade wind pattern in place. Will maintain a typical trade wind forecast for now until details become more clear.

Aviation

Robust high pressure far northeast of the area will weaken somewhat over the next 6 to 12 hours as it heads east. Breezy to strong trade winds will ease to moderate to locally breezy as the high's influence wanes. Showers, and any accompanying MVFR conditions, will mainly affect windward and mauka areas. VFR will hold sway otherwise.
AIRMETs remain in effect for moderate low level turbulence to the lee of the islands, and moderate upper level turbulence over the entire state and adjacent waters. Also, another AIRMET continues for mountain obscuration in windward sections of the Big Island. The turbulence AIRMETs will likely be extended at least through the late morning hours.

Marine

A large area of high pressure north of the state that has been producing fresh to locally strong trades will be on the move to the east and northeast today. The result will be a downtrend in trades the next few days. The Small Craft Advisory (SCA) has been scaled back to just include those waters from the Kaiwi Channel eastward. These relatively lighter moderate trades through Wednesday will be in response to an approaching front from the northwest. High pressure will be passing off to the far north Wednesday night through Friday. This will likely restrengthen trades back to fresh to locally strong magnitudes, along with a return to more elevated seas, Thursday and Friday. This scenario will likely have SCAs back in effect for the majority of the coastal waters.
Today's northwest swell will gradually lower through Tuesday. The next medium size northwest swell is timed to arrive Wednesday and pass through the islands into Friday. Small background south swells are expected through Friday with a slightly larger south swell scheduled around Saturday. Short period choppy east facing shore surf will remain elevated through the day with only a slight lowering Tuesday and Wednesday under moderate trade flow. East wind wave swell and surf will increase later this week in response to strengthened trades.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST this evening for Kaiwi Channel, 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.

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Data Courtesy of NOAA.gov