Hilo

Today: Showers likely, mainly before 1pm. Partly sunny, with a high near 82. West northwest wind 5 to 8 mph becoming northeast in the afternoon. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely, mainly after 7pm. Mostly cloudy, with a low around 66. North wind 5 to 7 mph becoming west after midnight. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Showers likely, mainly before 1pm. Partly sunny, with a high near 83. Light and variable wind becoming east northeast 5 to 10 mph in the afternoon. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Scattered showers after noon. Partly sunny, with a high near 78. Southeast wind 6 to 11 mph becoming light and variable in the afternoon. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly before midnight. Mostly cloudy, with a low around 63. Calm wind becoming east around 6 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Scattered showers after noon. Partly sunny, with a high near 78. Light and variable wind becoming west southwest 5 to 9 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Waimea

Today: Scattered showers. Partly sunny, with a high near 72. Windy, with a northeast wind 24 to 26 mph, with gusts as high as 38 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Scattered showers. Partly cloudy, with a low around 55. Windy, with a northeast wind 20 to 24 mph, with gusts as high as 34 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Tuesday: Scattered showers. Partly sunny, with a high near 73. Windy, with a northeast wind 14 to 24 mph, with gusts as high as 34 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Kohala

Today: Showers likely, mainly before noon. Partly sunny, with a high near 66. Windy, with an east wind around 26 mph, with gusts as high as 38 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely. Mostly cloudy, with a low around 54. Windy, with an east wind around 25 mph, with gusts as high as 36 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Showers likely, mainly before noon. Partly sunny, with a high near 67. Windy, with an east wind 20 to 25 mph, with gusts as high as 36 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Isolated showers after noon. Mostly sunny, with a high near 79. Windy, with an east wind 23 to 26 mph, with gusts as high as 34 mph. Chance of precipitation is 20%.

Tonight: Isolated showers before midnight. Partly cloudy, with a low around 72. Windy, with an east northeast wind 22 to 25 mph, with gusts as high as 32 mph. Chance of precipitation is 20%.

Tuesday: Isolated showers after noon. Mostly sunny, with a high near 79. Windy, with an east wind 22 to 25 mph, with gusts as high as 32 mph. Chance of precipitation is 20%.

Puna

Today: Showers likely, mainly before noon. Partly sunny, with a high near 79. Breezy, with a north wind 9 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely. Mostly cloudy, with a low around 63. North wind around 9 mph becoming west northwest after midnight. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

Tuesday: Showers likely, mainly before noon. Partly sunny, with a high near 80. West northwest wind 8 to 14 mph becoming east northeast in the afternoon. Winds could gust as high as 18 mph. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

Waikoloa

Today: Isolated showers after 1pm. Mostly sunny, with a high near 81. Windy, with an east northeast wind 17 to 26 mph, with gusts as high as 38 mph. Chance of precipitation is 20%.

Tonight: Isolated showers before 1am. Partly cloudy, with a low around 64. Windy, with an east northeast wind 18 to 25 mph, with gusts as high as 36 mph. Chance of precipitation is 20%.

Tuesday: Isolated showers after 1pm. Mostly sunny, with a high near 81. Breezy, with an east northeast wind 17 to 22 mph, with gusts as high as 31 mph. Chance of precipitation is 20%.

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