Photo Credit: Tyler Rooke

West Side

Today: Isolated showers before noon. Sunny, with a high near 84. Windy, with an east northeast wind 18 to 23 mph, with gusts as high as 32 mph. Chance of precipitation is 20%.

Tonight: Isolated showers. Mostly clear, with a low around 68. Windy, with an east northeast wind 20 to 24 mph, with gusts as high as 34 mph. Chance of precipitation is 20%.

Tuesday: Isolated showers before noon. Sunny, with a high near 84. Breezy, with an east northeast wind 15 to 20 mph decreasing to 9 to 14 mph in the afternoon. Winds could gust as high as 28 mph. Chance of precipitation is 20%.

South Side

Today: Isolated showers after noon. Mostly sunny, with a high near 85. Calm wind becoming west 5 to 7 mph in the afternoon. Chance of precipitation is 20%.

Tonight: Isolated showers before midnight. Mostly clear, with a low around 66. West southwest wind around 5 mph becoming calm after midnight. Chance of precipitation is 20%.

Tuesday: Isolated showers after noon. Sunny, with a high near 85. Light and variable wind becoming east northeast 5 to 10 mph in the afternoon. Chance of precipitation is 20%.

North Shore

Today: Scattered showers, mainly before noon. Mostly sunny, with a high near 81. Windy, with an east wind 16 to 25 mph, with gusts as high as 36 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly after midnight. Partly cloudy, with a low around 67. Windy, with an east wind 17 to 23 mph, with gusts as high as 32 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Scattered showers, mainly before noon. Mostly sunny, with a high near 81. Windy, with an east wind 15 to 25 mph, with gusts as high as 36 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Central Maui

Today: Scattered showers, mainly before noon. Mostly sunny, with a high near 82. Breezy, with an east northeast wind 10 to 15 mph increasing to 17 to 22 mph in the afternoon. Winds could gust as high as 31 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly after midnight. Partly cloudy, with a low around 66. Breezy, with a northeast wind 11 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Scattered showers, mainly before noon. Mostly sunny, with a high near 82. Breezy, with an east northeast wind 11 to 21 mph, with gusts as high as 29 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Upcountry

Today: Mostly sunny, with a high near 70. South southeast wind 5 to 9 mph becoming west in the morning.

Tonight: Partly cloudy, with a low around 54. West southwest wind around 6 mph becoming light and variable.

Tuesday: Sunny, with a high near 70. Southeast wind 5 to 13 mph becoming west in the morning.

East Maui

Today: Scattered showers. Partly sunny, with a high near 78. East wind 8 to 14 mph, with gusts as high as 18 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 65. East wind 5 to 9 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Scattered showers. Partly sunny, with a high near 78. East wind 6 to 14 mph, with gusts as high as 18 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Lanai City

Today: Isolated showers. Mostly sunny, with a high near 74. Windy, with a northeast wind 20 to 24 mph, with gusts as high as 34 mph. Chance of precipitation is 20%.

Tonight: Isolated showers. Partly cloudy, with a low around 63. Windy, with a northeast wind 16 to 23 mph, with gusts as high as 32 mph. Chance of precipitation is 20%.

Tuesday: Isolated showers. Mostly sunny, with a high near 75. Breezy, with a northeast wind 9 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 20%.

Kaunakakai

Today: Sunny, with a high near 81. Breezy, with an east northeast wind 8 to 18 mph, with gusts as high as 25 mph.

Tonight: Mostly clear, with a low around 69. Breezy, with an east wind 8 to 16 mph, with gusts as high as 22 mph.

Tuesday: Sunny, with a high near 82. Breezy, with an east wind 10 to 20 mph, with gusts as high as 28 mph.

Detailed Forecast

Synopsis

High pressure north of the state will keep moderate trade winds in place through the work week, with showers favoring windward and mauka areas along with the occasional leeward spillover. An increase in deep moisture may bring more humid conditions and an increase in rain chances to the islands this weekend.

Discussion

Currently at the surface, a 1029 mb high is centered around 1250 miles north of Honolulu, and is driving moderate trade winds across the island chain early this morning. Infrared satellite imagery shows partly to mostly cloudy skies across the state, with cloud cover most prevalent over windward areas. Meanwhile radar imagery shows scattered to numerous showers moving into windward areas, with a quite a few showers spilling into leeward locales. The main forecast concern during the next week revolves around the potential for some deeper moisture moving into the state this weekend.
High pressure north of the islands will shift slowly eastward during the next few days, then remain nearly stationary far northeast of the state late in the work week through the weekend. Moderate trade winds will generally prevail through the period, with the trades likely strongest early in the week and weaker late in the week.
As for the remaining weather details, precipitable water values are forecast to remain below seasonal levels in the 0.8 to 1.2 inch range through the work week. This should keep rainfall amounts fairly light and focused primarily over windward and mauka areas with the occasional leeward spillover. The GFS and to a lesser extent the ECMWF, show an increase in deep moisture spreading over the islands this weekend. At a minimum, this should lead to an increase in rainfall chances and higher humidity levels across the state, although the potential for more significant rainfall amounts remains unclear at the moment.

Aviation

A high pressure ridge north of the region will maintain breezy trade winds today. Upper level instability will keep passing showers in the forecast, favoring windward and mountain areas. Mostly VFR conditions are expected with brief periods of MVFR conditions in showers.
AIRMET Tango remains in effect for moderate turbulence south through west of mountains. Breezy trade winds will likely keep this AIRMET in effect through today.

Marine

Fresh to strong trade winds will continue through the first half of the week, then potentially trend down slightly by the weekend as a weakness in the ridge forms to the north. Seas will hover below the 10 ft advisory criteria for most waters through the first half of the week, then lower by the weekend. The exception will be across the Alenuihaha Channel today through Tuesday when seas may reach 10 ft.
Surf along exposed north and west facing shores will trend up this week due to a couple of small, late season, northwest swells arriving and moving through. The first one should fill in and peak later today into Tuesday, then fade by midweek. The second one should fill in Wednesday and ease Thursday into Friday.
Surf along south facing shores will continue to lower today with very little expected through the remainder of the week. For the long range, another decent, long-period southerly pulse will be possible through the last week of the month.
Surf along east facing shores will remain rough due to the strong trades in place. A slight downward trend will be possible by the weekend.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov