West Kaua’i

Rest Of Tonight: Partly cloudy with isolated showers. Lows 66 to 71 near the shore to around 59 above 3000 feet. East winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs 79 to 86 near the shore to around 73 above 3000 feet. East winds up to 10 mph shifting to the south around 10 mph in the afternoon. Chance of rain 20 percent.

Saturday Night: Mostly clear. Isolated showers in the evening. Lows around 67 near the shore to around 57 above 3000 feet. South winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

South Kaua’i

Rest Of Tonight: Partly cloudy with isolated showers. Lows around 69. Southwest winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Saturday: Sunny. Isolated showers in the morning. Highs 79 to 86. Southwest winds up to 10 mph. Chance of rain 20 percent.

Saturday Night: Mostly clear. Lows around 67. Light winds.

Kaua’i Mountains

Rest Of Tonight: Mostly cloudy in the evening then becoming mostly clear. Scattered showers in the evening, then isolated showers after midnight. Lows 58 to 69 in the valleys to around 57 above 4000 feet. Southwest winds up to 10 mph. Chance of rain 50 percent.

Saturday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 75 to 82 in the valleys to around 65 above 4000 feet. South winds up to 10 mph. Chance of rain 40 percent.

Saturday Night: Partly cloudy with isolated showers. Lows 57 to 67 in the valleys to around 56 above 4000 feet. Light winds. Chance of rain 20 percent.

North Kaua’i

Rest Of Tonight: Mostly clear. Isolated showers in the evening. Lows 62 to 68. South winds up to 10 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs 76 to 83. South winds up to 10 mph in the morning becoming light. Chance of rain 20 percent.

Saturday Night: Mostly clear. Lows 60 to 68. Light winds.

East Kaua’i

Rest Of Tonight: Mostly clear with isolated showers. Lows 62 to 72. Southwest winds around 10 mph. Chance of rain 20 percent.

Saturday: Sunny with isolated showers. Highs 74 to 85. South winds up to 10 mph. Chance of rain 20 percent.

Saturday Night: Mostly clear. Lows 61 to 70. Light winds.

Detailed Forecast

Synopsis

Southerly winds will persist across the western half of the state while southeasterlies persist across the eastern half through tomorrow, focusing light showers over leeward and mauka areas. Trade winds will return by Sunday and focus showers over windward and mauka areas, with a wetter pattern starting Tuesday.

Discussion

Relatively dry and stable conditions continue this afternoon with visible satellite imagery showing scattered low-topped cumulus moving into leeward sections of Kauai and Oahu, along with sea breezes building clouds over windward slopes of Maui County and nearly all slopes of the Big Island. Radar is picking up very little in the way of rainfall, with most areas rain-free.
As a front north of Kauai lifts northeast of the area and another files in quickly behind it, the surface ridge centered to the east- northeast of the state will continue to be confined to an area just south of its usual position, with its horizontal axis extending across the island chain. Due to the orientation of the surface ridge, a southeasterly flow will persist across the eastern half of the state and a southerly flow across the western half through tomorrow. With wind speeds on the lighter side, sea breezes will likely bring an uptick in cloud cover and a few isolated showers over island interiors through the rest of this afternoon and again tomorrow. Overall, rainfall accumulations will be minimal through the weekend due to a combination of subsidence from a mid- level ridge building in from the west and drier air filtering across the area helping to put a damper on shower activity.
On Sunday, trades will begin to return as the surface high builds to the northeast and the ridge axis lifts north of the state. As another, stronger high slides eastward north of the state early next week, easterly trades will strengthen each day becoming breezy by Monday and windy by Tuesday. By this point in the week, the mid-level ridge will be overtop the island chain and low- to mid- level moisture will be limited (through Monday), keeping shower activity suppressed, with a few windward showers possible, especially overnight into the early morning hours. Batches of moisture caught up in the trades will begin moving across the state on Tuesday and continue through the rest of the week.
Vog continues to impact mainly the eastern half of the state as can be seen in this afternoon's GOES GeoColor imagery, web cams and air quality observations. If the current pause in volcanic eruption activity continues, vog coverage may decrease as the week progresses. As the trades build back into the islands next week, any lingering vog upstream of the islands could be carried back across the islands.

Aviation

Light to moderate southerly winds over the western half of the island chain and southeasterlies over the eastern half will prevail through Saturday. Dry and stable conditions will continue as well, with only isolated showers/low clouds possible along south and east facing slopes. Aside from brief MVFR conditions in showers, VFR will prevail. Hazy conditions should continue through at least tomorrow for most areas due to VOG from Kilauea being carried north southerly winds. This could lead to pockets of reduced visibility, especially for the Kona airport. Winds will gradually transition to easterly trades on Sunday.
No AIRMETs in effect, nor expected through tonight.

Marine

Weak high pressure will stagnate over the islands in maintenance of light to moderate ESE winds through the weekend. As the mid- latitude storm track rebounds northward, so too will resident high pressure as it strengthens and supports the return of trades by Monday which quickly become fresh to strong for the remainder of the week. Small Craft Advisories for wind will likely be needed during this time.
Extra large NW (320) swell appears to have peaked at offshore NDBC Buoys 51001 and 51101, but still remains quite elevated averaging around 13 feet 15 seconds. This essentially bakes in High Surf Warning (HSW) threshold waves through much of the night. The existing HSW through 6am HST therefore remains in good shape. NDBC Buoy 51213 adjacent to Lanai has held steady at 3 feet 15 seconds suggesting limited potential for an upgrade to the High Surf Advisory (HSA) for west facing shores of the Big Island. The 320 degree trajectory of the swell has been a limiting factor here. This swell will slowly subside during the next couple of days. The Small Craft Advisory for elevated seas remains in effect.
The next swell in the sequence, a large long period NW (310) swell will build early next week with high confidence that HSA thresholds will be reached for select N and W facing shores Monday and Tuesday. This swell will then gradually lower through Thursday with a new large northwest swell possible late next week.
Surf along S facing shores will remain very small and dominated by background energy through late next week. Surf along E facing shores will remain very small through the weekend before rising to above-normal levels with returning trades next week.

HFO Watches/Warnings/Advisories

High Surf Warning until 6 AM HST Saturday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kauai North, Molokai Windward, Molokai North, Molokai West, Windward Haleakala.
High Surf Advisory until 6 AM HST Saturday for Kona, Kohala.
Small Craft Advisory until 6 AM HST Saturday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Alenuihaha Channel, Big Island Windward Waters.

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