Hilo

Today: Occasional showers in the morning, then showers likely in the afternoon. Highs 78 to 84 near the shore to 67 to 72 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain near 100 percent.

Tonight: Occasional showers. Lows around 68 near the shore to around 54 at 4000 feet. Northeast winds up to 15 mph. Chance of rain near 100 percent.

Columbus Day: Occasional showers in the morning, then showers likely in the afternoon. Highs 78 to 84 near the shore to 67 to 72 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain near 100 percent.

Kona

Today: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Haze through the day. Highs around 85 near the shore to around 72 near 5000 feet. West winds up to 10 mph with gusts to 50 mph. Chance of rain 30 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Haze. Lows 68 to 75 near the shore to around 54 near 5000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Columbus Day: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Haze through the day. Highs around 85 near the shore to around 72 near 5000 feet. Light winds. Chance of rain 30 percent.

Waimea

Today: Windy. Mostly cloudy with showers likely. Highs around 80 near the shore to 72 to 79 near 3000 feet. East winds 10 to 30 mph with gusts to 50 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then showers likely after midnight. Lows around 67 near the shore to 54 to 61 near 3000 feet. East winds 15 to 25 mph. Chance of rain 70 percent.

Columbus Day: Breezy. Mostly cloudy with showers likely. Highs around 80 near the shore to 72 to 79 near 3000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Kohala

Today: Windy. Mostly cloudy with showers likely. Highs around 80 near the shore to 72 to 79 near 3000 feet. East winds 10 to 30 mph with gusts to 50 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then showers likely after midnight. Lows around 67 near the shore to 54 to 61 near 3000 feet. East winds 15 to 25 mph. Chance of rain 70 percent.

Columbus Day: Breezy. Mostly cloudy with showers likely. Highs around 80 near the shore to 72 to 79 near 3000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

South Big Island

Today: Windy. Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Haze through the day. Highs around 84 near the shore to around 73 near 5000 feet. East winds 15 to 30 mph with gusts to 50 mph. Chance of rain 30 percent.

Tonight: Breezy. Mostly cloudy with isolated showers in the evening, then partly cloudy after midnight. Haze through the night. Lows around 68 near the shore to around 53 near 5000 feet. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Columbus Day: Breezy. Sunny in the morning, then partly sunny with scattered showers in the afternoon. Haze through the day. Highs around 84 near the shore to around 73 near 5000 feet. East winds 10 to 20 mph. Chance of rain 30 percent.

Puna

Today: Occasional showers in the morning, then showers likely in the afternoon. Highs 78 to 84 near the shore to 67 to 72 at 4000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain near 100 percent.

Tonight: Occasional showers. Lows around 68 near the shore to around 54 at 4000 feet. Northeast winds up to 15 mph. Chance of rain near 100 percent.

Columbus Day: Occasional showers in the morning, then showers likely in the afternoon. Highs 78 to 84 near the shore to 67 to 72 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain near 100 percent.

Waikoloa

Today: Mostly sunny in the morning then becoming partly sunny. Windy. Isolated showers. Highs around 84 near the shore to 68 to 74 above 4000 feet. Northeast winds up to 30 mph with gusts to 50 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 69 to 75 near the shore to 50 to 57 above 4000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Columbus Day: Sunny in the morning then becoming partly sunny. Isolated showers. Highs around 84 near the shore to 68 to 74 above 4000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A strong area of high pressure north of the islands will keep windy conditions in place during the next couple of days. Clouds and showers will favor windward and mauka areas, but will also reach leeward areas more regularly due to the strength of the trades. A wet trade wind pattern will develop late Monday and continue through early Wednesday as a disturbance aloft combines with a plume of deep moisture moving in from the east. Drier conditions and more typical trade wind weather is forecast to return Wednesday afternoon through next weekend.

Discussion

Currently at the surface, a 1040 mb high is centered around 1700 miles north-northeast of Honolulu, while a trough of low pressure is located around 800 miles east-southeast of Hilo. These features are producing a very tight pressure gradient and windy conditions across the island chain early this morning. Infrared satellite imagery shows partly to mostly cloudy conditions in most areas, with cloud coverage the greatest in windward locales. Radar imagery shows numerous showers moving into windward areas, with quite a few showers also spilling over into leeward areas. Main short term concerns continue to revolve around rain chances and trade wind trends during the next couple days.
A series of reinforcing highs building to the north of the islands will keep strong trade winds in place through most of the forecast period. The trades will remain very strong through the remainder of the weekend, and a Wind Advisory continues through 6 PM this evening. The gradient will ease ever so slightly during the first half of the work week, but breezy to locally windy conditions will likely continue Monday through Wednesday. The trades should drop a notch lower late in the work week, with moderate to locally breezy conditions expected Thursday through next weekend.
As for the remaining weather details, a fairly typical trade wind shower regime should hold in place through Monday, although slightly deeper moisture over the eastern end of the state will likely keep shower coverage a bit higher over Maui and the Big Island. Showers will continue to favor windward slopes and coasts, although the strong trades will also deliver passing showers to leeward areas at times.
A plume of deep tropical moisture is expected to move into the eastern islands late Monday, then overspread the remainder of the island chain Monday night through Tuesday night, before exiting to the west Wednesday morning. Precipitable water values climb into the 1.5 to 2.0 inch range, with low level inversions getting eliminated as a disturbance aloft moves over the islands. This should result in wet trade wind weather across the state, with some downpours likely, particularly over windward slopes and coasts. The strong trades will continue to carry showers into leeward communities more regularly as well. A more typical trade wind regime is then forecast to return Wednesday afternoon and continue through next weekend.

Aviation

Strong high pressure centered far north of the islands will continue to maintain strong and gusty trade winds into this evening. Therefore, AIRMET Tango continues for strong surface winds greater than 30 kt across most of Maui and the Big Island, as well as the adjacent waters. In addition, AIRMET Tango remains in effect for low level turbulence below 8 thousand feet downwind of the higher terrain on all islands. This AIRMET will likely continue through Monday.
Low clouds and showers embedded within the strong low level trade wind flow continue to push into the islands from the east- northeast. Therefore, expect periods of MVFR conditions along most windward sections today. Also, some low clouds and brief showers will likely be transported over to the leeward sides of some of the smaller islands due to the strong trades, especially through mid-morning and again tonight.
AIRMET Sierra remains in effect for mountain obscuration along the windward slopes of Maui and the Big Island. We recently added the windward slopes of Molokai and Oahu to this AIRMET. This AIRMET may be required for windward Kauai if conditions deteriorate later this morning.

Marine

Hazardous marine conditions will continue today due to strong- to gale-force trade winds and large seas ranging from 10 to 15 feet. The gales and largest seas can be expected over the typically windy waters around Maui and the Big Island, where a Gale Warning remains in effect through 6 PM today. For all other waters, a Small Craft Advisory remains in effect and has been extended through Monday due to a combination of winds and seas. Although a gradual downward trend (winds/seas) is anticipated by midweek, advisory-level winds will remain likely for the windier waters/channels around Maui and the Big Island through much of the week.
Surf along east facing shores will remain rough through the week due to the aforementioned winds and seas. Surf heights, however, should dip below the 10 ft (face) advisory-level Monday, then continue to lower through midweek.
Surf along south facing shores will hold around the advisory level today, then slowly ease through the first half of the week as the late season south swell moves out. Observations at the offshore buoys to the south reflect this swell holding above predicted levels early this morning, with the bulk of the energy now centered within the 15-17 second bands.
Surf along north facing shores will remain small through the first half of the week. The exception will be at north facing locations exposed to the trade wind energy, which will result in rough conditions. Guidance does show a gale racing eastward across the Kamchatka Peninsula and southern Bering Sea Monday through Tuesday with a short-lived fetch setting up within the 315 to 330 directional band relative to Hawaii. WAVEWATCH III reflects this and depicts a small, long-period northwest swell arriving Thursday night into Friday.

Fire weather

With KBDI values above 600, low daytime relative humidities and windy trades, the Red Flag Warning remains in effect through 6 PM this evening. If conditions warrant, it may need to be extended through Monday as well.

HFO Watches/Warnings/Advisories

Red Flag Warning until 6 PM HST this evening for Kauai Leeward, Oahu South Shore, Waianae Coast, Oahu North Shore, Olomana, Central Oahu, Waianae Mountains, Molokai Leeward, Maui Leeward West, Maui Central Valley, Leeward Haleakala, Kona, Kohala, Big Island Interior.
High Surf Advisory until 6 PM HST this evening for Niihau, Kauai Leeward, Waianae Coast, Olomana, Kahoolawe, Maui Leeward West, Kona, Kauai East, Kauai South, East Honolulu, Honolulu Metro, Ewa Plain, Koolau Windward, Molokai Windward, Molokai Southeast, Molokai Leeward South, Lanai Leeward, Lanai South, Maui Central Valley South, Windward Haleakala, Kipahulu, South Maui/Upcountry, South Haleakala, Big Island South, Big Island Southeast, Big Island East, Big Island North.
Wind Advisory until 6 PM HST this evening for Kauai Leeward, Kauai Mountains, Waianae Coast, Oahu North Shore, Olomana, Central Oahu, Waianae Mountains, Lanai Mauka, Kahoolawe, Maui Windward West, Maui Leeward West, Kohala, Big Island Interior, Kauai North, Kauai East, Kauai South, East Honolulu, Honolulu Metro, Ewa Plain, Koolau Windward, Koolau Leeward, Molokai, Lanai Windward, Lanai Leeward, Lanai South, Maui Central Valley North, Maui Central Valley South, Windward Haleakala, Kipahulu, South Maui/Upcountry, South Haleakala, Big Island South, Big Island Southeast, Big Island North.
Gale Warning until 6 PM HST this evening for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 PM HST Monday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.

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Data Courtesy of NOAA.gov