Hilo

Today: Mostly cloudy with scattered showers. Highs 80 to 85 near the shore to 66 to 72 at 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Cloudy with occasional showers. Lows 66 to 73 near the shore to 57 to 62 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 90 percent.

Sunday: Mostly cloudy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 80 to 85 near the shore to 66 to 72 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 80 percent.

Kona

Today: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 84 to 89 near the shore to around 69 near 5000 feet. Light winds becoming west up to 10 mph in the afternoon. Chance of rain 40 percent.

Tonight: Mostly cloudy. Lows 71 to 76 near the shore to 53 to 58 near 5000 feet. North winds up to 10 mph.

Sunday: Partly sunny. Scattered showers in the afternoon. Highs 85 to 90 near the shore to around 71 near 5000 feet. North winds around 10 mph. Chance of rain 50 percent.

Waimea

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 67 to 85. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Showers likely in the evening, then scattered showers after midnight. Lows 66 to 72 near the shore to 59 to 66 near 3000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Sunday: Breezy. Mostly cloudy with scattered showers. Highs 67 to 86. East winds 10 to 20 mph. Chance of rain 50 percent.

Kohala

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs 67 to 85. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Breezy. Showers likely in the evening, then scattered showers after midnight. Lows 66 to 72 near the shore to 59 to 66 near 3000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Sunday: Breezy. Mostly cloudy with scattered showers. Highs 67 to 86. East winds 10 to 20 mph. Chance of rain 50 percent.

South Big Island

Today: Breezy. Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 85 near the shore to around 68 near 5000 feet. East winds 10 to 20 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Breezy. Isolated showers. Lows around 74 near the shore to around 55 near 5000 feet. East winds 15 to 20 mph. Chance of rain 20 percent.

Sunday: Mostly sunny in the morning then becoming mostly cloudy. Breezy. Isolated showers. Highs around 85 near the shore to around 68 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Puna

Today: Mostly cloudy with scattered showers. Highs 80 to 85 near the shore to 66 to 72 at 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Cloudy with occasional showers. Lows 66 to 73 near the shore to 57 to 62 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 90 percent.

Sunday: Mostly cloudy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 80 to 85 near the shore to 66 to 72 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 80 percent.

Waikoloa

Today: Mostly sunny. Scattered showers in the afternoon. Highs 84 to 89 near the shore to 67 to 73 above 4000 feet. North winds up to 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Isolated showers after midnight. Lows around 75 near the shore to around 55 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 84 to 91 near the shore to 69 to 75 above 4000 feet. Northeast winds around 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Clouds and showers will favor windward and mauka areas as a locally breezy trade wind weather pattern continues through the forecast period. A surface trough passing south of the islands will increase shower coverage over windward Big Island late today into Sunday.

Discussion

There is little to no change in forecast philosophy from last evening. Strong high pressure to the north of the islands will maintain breezy trade winds across local waters through the weekend and into next week. Our airmass will remain stable, but showery low clouds will continue to push primarily across windward and mauka areas. Some showers will push westward across leeward areas. A weak surface trough is passing through the islands, supporting showery low clouds over and upstream from the smaller islands. This trough will pass westward today.
Models show another trough, far southeast of the Big Island, passing westward just south of the state tonight and Sunday. While the bulk of the associated moisture is expected to remain south of the islands, some of it will move over the chain, most notably over the Big Island and Maui. This will likely lead to an increase in shower coverage before the moisture moves west of the islands early Monday. Drier trade wind weather will then resume through the rest of the forecast period. Trade wind speeds will likely receive a subtle boost as the trough passes by.

Aviation

The batch of clouds and showers that were impacting the islands for the first part of the night have moved to the west of the islands. Another small batch of clouds and showers are making their way over Oahu at the 3 am hour, and will likely reach Kauai shortly. These clouds and showers could bring some brief MVFR conditions, but at this time, am holding off on any AIRMETs. The windward sides of the remaining islands have been largely VFR over the last few hours, and are expected to remain so as we head into the morning. Clouds and showers are expected to increase over the Big Island later today and into tonight as another batch of moisture reaches the southern end of the state.
Moderate to locally breezy trade winds are expected to continue through the weekend. AIRMET Tango is in effect for mechanical turbulence to the lee of the mountains below 9000 ft. With little change in the winds expected, the AIRMET is expected to continue through the weekend.

Marine

A ridge of high pressure far north of the state will maintain trade winds mostly in the moderate to locally strong range through next week.
During the past few hours the trade winds have eased off west of Molokai, remaining in the moderate to locally strong range across the typically windy nearshore waters of Maui County and waters south of the Big Island. Thus the Small Craft Advisory (SCA) has been scaled back to those waters. But this could be temporary.
A surface trough, currently 390 nm southeast of the Big Island, is slated to move northwest into the far southeast offshore waters this afternoon. The trough will take a more westerly course thereafter, grazing the Big Island early Sunday, then dissipate as it passes south of the smaller islands the rest of Sunday and Sunday night. While passing south of the islands, the trough will tighten the pressure gradient around the islands, resulting in a boost in the trade winds to moderate to strong tonight and Sunday. In doing so, the SCA will likely be expanded.
The north-northwest swell has lowered enough where we can cancel the High Surf Advisory for the north facing shores of most islands and west facing shores of Kauai. This swell will continue to lower through the rest of the weekend. Surf along north facing shores appear small next week, with only small pulses from the north and north- northwest.
For the south facing shores, Wave Watch III is indicating no long period pulses of greater than 13 seconds, between Sunday and Tuesday night. A 16 to 18 second period swell, although small, is slated to reach our south facing shores next week Wednesday, and lasting through Friday. East facing shores will have moderate surf, thanks to the moderate to strong trades that will hold pretty much through the weekend.

HFO Watches/Warnings/Advisories

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

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Data Courtesy of NOAA.gov