Photo Credit: Joan M. Flake

West Side

Today: Breezy. Mostly sunny with isolated showers. Highs 75 to 87. East winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 66 to 74. East winds 10 to 20 mph. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs 75 to 86. East winds 10 to 20 mph. Chance of rain 20 percent.

South Side

Today: Mostly sunny. Breezy. Highs around 87. North winds 10 to 25 mph.

Tonight: Partly cloudy. Breezy. Isolated showers after midnight. Lows 65 to 73. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs around 87. North winds 10 to 20 mph. Chance of rain 20 percent.

North Shore

Today: Partly sunny. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 74 to 83 near the shore to around 63 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with showers likely. Lows around 69 near the shore to 47 to 53 near 5000 feet. Southeast winds 10 to 20 mph. Chance of rain 70 percent.

Saturday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 75 to 82 near the shore to around 63 near 5000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Central Maui

Today: Breezy. Mostly sunny with isolated showers. Highs 81 to 88. East winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 65 to 71. East winds 10 to 20 mph. Chance of rain 20 percent.

Saturday: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs 80 to 87. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny with scattered showers. Highs around 60 at the visitor center to around 55 at the summit. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers. Lows around 45 at the visitor center to around 42 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

Saturday: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs around 59 at the visitor center to around 56 at the summit. East winds 10 to 15 mph. Chance of rain 50 percent.

East Maui

Today: Partly sunny. Breezy. Showers likely in the morning, then scattered showers in the afternoon. Highs 74 to 83 near the shore to around 63 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with showers likely. Lows around 69 near the shore to 47 to 53 near 5000 feet. Southeast winds 10 to 20 mph. Chance of rain 70 percent.

Saturday: Mostly cloudy. Showers likely in the morning, then scattered showers in the afternoon. Highs 75 to 82 near the shore to around 63 near 5000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Lanai City

Today: Breezy. Partly sunny with isolated showers. Highs 72 to 81. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 61 to 66. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Saturday: Mostly sunny in the morning then becoming partly sunny. Breezy. Isolated showers. Highs 72 to 80. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Kaunakakai

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs 66 to 86. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 56 to 73. East winds 10 to 20 mph. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs 66 to 86. East winds 10 to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate to fresh trade winds will continue into the weekend into the new week. Expect showers to favor windward and mauka locations mostly overnight through the morning periods through Saturday. A wetter, more unstable pattern is expected with the new week as an upper level system moves in from the north.

Discussion

High pressure far to the northeast continues to bring in moderate to fresh trades to the region. The global models keep the high in place through the weekend and have it reinforced early next week. As a result, expect trade winds to remain in place for the foreseeable future, and if anything, nudge upwards with the new week.
An upper level trough to the north of the islands, coupled with a mid to upper level low and associated trough to the far west of the islands, are helping to usher high clouds from the west, towards the islands. Satellite shows these high clouds beginning to move over the Big Island. Expect high clouds to spread across the islands over the next couple of days.
The global models agree with the trough to the north of the islands sinking southward over the next several days, with the development of a mid to upper level low along the trough to the northeast of the islands. The models diverge in placement and strength of this system, so several details are yet to emerge for the forecast next week. What can be agreed is that surface winds look to remain out of the east, but the trade wind inversion will likely be eroded as the upper level feature moves over the islands. Additional moisture will be drawn northward over the southern end of the state. This will allow for enhanced showers, and more showers reaching interior and leeward areas.
Have boosted some PoPs over some interior and leeward areas many during the Sunday through Tuesday time span keeping in line with the latest model data. There is still some uncertainty with the extent of the instability that will move into the islands with this system. However with the ECMWF continuing to show the potential for thunderstorms near the Big Island, and the GFS which is slowly showing a trend towards more of what the ECMWF has been indicating, have gone ahead and put the slight chance of thunderstorms in for the Big Island and waters to east of the Big Island for Sunday afternoon and evening. Will need to monitor future model runs to see if we need to increase the chance and/or areal coverage of thunderstorms.
Midweek looks like a return to more typical trade wind weather with moderate trades.

Aviation

Moderate to locally breezy trade winds will continue to steer bands of light showers towards the Hawaiian Islands. Clouds and showers will favor east and northeast facing slopes and coasts, especially in the late night and morning hours. In the afternoon and early evening, leeward sea breezes will encourage shower development over island interiors.
As of 2 am Friday, satellite imagery revealed several bands of stratocumulus embedded in the trade wind flow just upstream of the Big Island and Maui. These weak showers should move onshore within the next few hours and may cause areas of mountain obscuration across windward Big Island later this morning.
AIRMET Tango for low level mechanical turbulence to the lee of higher terrain remains in effect for Molokai, Maui, and the Big Island. Conditions are expected to persist into Saturday.
Additionally, a strengthening upper level jet is expected to yield moderate upper level turbulence across the majority of the state beginning this afternoon.

Marine

A surface high pressure system centered far northeast of the islands is expected to build as it moves slowly westward during the next few days. This will cause the pressure gradient to tighten across the state, which will produce locally strong trade winds. Therefore, a Small Craft Advisory (SCA) remains in effect for the typically windier waters adjacent to the islands of Maui County and the Big Island through Saturday night. Additional Hawaiian waters will likely be added to the SCA starting Sunday as the trade winds continue to strengthen across the island chain later this weekend and early next week.
The current northwest swell will maintain small surf along most north and west facing shores of the smaller islands through this evening. A small, reinforcing northwest swell arriving early Saturday will likely cause a modest increase in surf heights along exposed north and west facing shores of the smaller islands this weekend. A new moderate, long-period northwest swell arriving late Sunday is expected to cause surf to increase along most north and west facing shores early next week. The latest wave model guidance continues to show this northwest swell will gradually build, and surf may approach the High Surf Advisory criteria along some north and west facing shores of the smaller islands from late Tuesday into Wednesday.
Small south and southwest swells will keep small background surf along south facing shores through Saturday. A new, long-period south-southwest swell arriving Sunday is expected to cause surf to increase well above the summertime average along south facing shores from Monday through the middle of next week.
Expect modest, choppy surf along east facing shores through tonight. However, the strengthening trade winds will produce increasing surf along east facing shores this weekend. The strong trade winds in the vicinity of, as well as upstream of the islands will likely result in above average, rough surf along east facing shores from Monday into mid-week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM 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