Hilo

Tonight: Mostly cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 64 to 71 near the shore to 54 to 59 at 4000 feet. North winds up to 10 mph. Chance of rain 90 percent.

Sunday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 80 to 87 near the shore to 67 to 73 at 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Sunday Night: Cloudy with occasional showers. Locally heavy rainfall possible after midnight. Lows 66 to 73 near the shore to 57 to 62 at 4000 feet. Southeast winds up to 10 mph shifting to the west after midnight. Chance of rain 90 percent.

Kona

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 71 to 76 near the shore to 49 to 54 near 5000 feet. Light winds becoming north up to 10 mph after midnight. Chance of rain 40 percent.

Sunday: Mostly sunny. Scattered showers in the afternoon. Highs around 87 near the shore to around 70 near 5000 feet. Light winds becoming northwest around 10 mph in the afternoon. Chance of rain 50 percent.

Sunday Night: Partly cloudy with isolated showers. Lows around 76 near the shore to 52 to 57 near 5000 feet. Light winds becoming northeast around 10 mph after midnight. Chance of rain 20 percent.

Waimea

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 63 to 72 near the shore to 56 to 63 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Sunday: Breezy. Partly sunny with scattered showers. Highs 66 to 85. East winds 10 to 20 mph. Chance of rain 50 percent.

Sunday Night: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 66 to 73 near the shore to 59 to 66 near 3000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Kohala

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 63 to 72 near the shore to 56 to 63 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Sunday: Breezy. Partly sunny with scattered showers. Highs 66 to 85. East winds 10 to 20 mph. Chance of rain 50 percent.

Sunday Night: Mostly cloudy. Scattered showers in the evening, then showers likely after midnight. Lows 66 to 73 near the shore to 59 to 66 near 3000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

South Big Island

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 74 near the shore to around 52 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Sunday: Sunny and breezy. Isolated showers in the afternoon. Highs around 88 near the shore to around 72 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Sunday Night: Mostly cloudy with scattered showers. Lows around 76 near the shore to around 56 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Puna

Tonight: Mostly cloudy. Showers likely in the evening, then occasional showers after midnight. Lows 64 to 71 near the shore to 54 to 59 at 4000 feet. North winds up to 10 mph. Chance of rain 90 percent.

Sunday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 80 to 87 near the shore to 67 to 73 at 4000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Sunday Night: Cloudy with occasional showers. Locally heavy rainfall possible after midnight. Lows 66 to 73 near the shore to 57 to 62 at 4000 feet. Southeast winds up to 10 mph shifting to the west after midnight. Chance of rain 90 percent.

Waikoloa

Tonight: Mostly clear. Isolated showers in the evening. Lows around 75 near the shore to 51 to 56 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Highs 84 to 90 near the shore to 67 to 73 above 4000 feet. East winds up to 10 mph shifting to the northwest around 10 mph in the afternoon.

Sunday Night: Partly cloudy with isolated showers. Lows around 77 near the shore to around 57 above 4000 feet. Light winds becoming east around 10 mph after midnight. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Locally breezy trade winds will continue through the rest of the weekend and into next week. Passing showers will favor mainly windward and mountain areas, especially during the overnight through early morning hours each day. Deeper moisture will move over the islands Sunday night and Monday, likely bringing increased shower coverage. Some of these showers could be heavy at times over the Big Island, where the greatest moisture is anticipated.

Discussion

Broad high pressure north of the the main Hawaiian Islands centered near 40N is driving locally breezy trade winds across the state this afternoon as a low-level trough north-northwest of the islands moves west. This trough will continue to move west and eventually dissipate through the rest of the weekend. Meanwhile, latest satellite and radar imagery shows scattered clouds and a few showers favoring primarily windward and mountain areas. Additionally, sea-breeze induced surface convergence has sparked the usual afternoon cloud buildups along the leeward coast of the Big Island as well.
Stable and relatively dry conditions will persist into early this evening as drier air moves over the islands. However, gradual moistening is likely to resume tonight into Sunday leading to passing showers over windward areas and possibly a few sprinkles over leeward areas as well. The best shower chances will be during the overnight through early morning hours.
Model guidance continues to indicate that a sharp 700 mb trough that can be seen on satellite imagery about 650 miles southeast of the Big Island will move west and bring increased low- and mid- level moisture over the islands from Sunday night through Monday. Although low-level winds may only veer slightly to the east- southeast, the 700 mb flow will become southerly as the trough passes, leading to moisture extending as high as 12-15 kft, mainly over the Big Island. With precipitable water expected to exceed 2 inches, the forecast continues to include the mention of heavy showers over the Big Island Sunday night into Monday. While the moisture increase over the smaller islands is not expected to be as deep, at least a modest increase in windward showers is also likely.
After the trough moves west of the islands Tuesday and Wednesday, a more typical trade wind regime will return to the state. Though confidence is low, guidance shows decreasing and veering winds are possible for a short period around the the end of next week, with trade winds increasing again thereafter.

Aviation

Broad high pressure will far north of Hawaii will maintain moderate to breezy trade winds through the weekend. Stable conditions will prevail, with only limited areas of MVFR conditions over windward slopes through the afternoon. More widespread MVFR conditions are expected to develop over windward areas tonight. Aside from afternoon clouds over Kona slopes of the Big Island, VFR will dominate leeward.
With the increased trade winds, AIRMET Tango for low-level turbulence over and downwind of terrain is in effect.

Marine

Moderate to locally strong trades will continue into next week as broad high pressure strengthens over the northeast Pacific. A Small Craft Advisory (SCA) remains posted for the typical windier waters of Maui County and the Big Island through Sunday night. The SCA may eventually require an extension through the first half of next week as the high remains nearly stationary.
Choppy surf along east facing shores will hold through the first half of next week due to persistent trades locally and upstream. A small, long-period south-southwest swell will peak today, generating small surf through Sunday before declining Monday. Background southeast and south swells will then keep tiny surf along south facing shores through much of next week. Surf along north facing shores will remain nearly flat through much of next week. Models show a gale low developing and tracking along the Aleutian Islands early next week that may send a small northwest swell into the local waters toward the end of next week.
Water levels at local tide gauges are running over half a foot above predicted and are expected to reach above the 1 foot Mean Higher High Water threshold for coastal inundation over the next several afternoons due to above normal water levels coinciding with the spring tides. The Coastal Flood Statement is now in effect for this threat through Tuesday and may need to be extended through Wednesday.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Monday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov