Hilo

Today: Mostly cloudy with numerous showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 80 to 86 near the shore to 66 to 72 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Tonight: Partly cloudy with scattered showers. Lows 64 to 71 near the shore to 53 to 58 at 4000 feet. Northwest winds up to 15 mph. Chance of rain 40 percent.

Wednesday: Partly sunny with scattered showers. Highs 80 to 85 near the shore to 65 to 73 at 4000 feet. Southwest winds 10 to 15 mph shifting to the east in the afternoon. Chance of rain 40 percent.

Kona

Today: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 84 to 89 near the shore to around 70 near 5000 feet. West winds up to 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 70 to 75 near the shore to 46 to 53 near 5000 feet. Light winds becoming east up to 10 mph after midnight. Chance of rain 20 percent.

Wednesday: Sunny. Isolated showers in the afternoon. Highs around 87 near the shore to around 71 near 5000 feet. East winds around 10 mph shifting to the west in the afternoon. Chance of rain 20 percent.

Waimea

Today: Windy. Mostly sunny with scattered showers. Highs around 82 near the shore to 71 to 80 near 3000 feet. East winds up to 30 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 63 to 72 near the shore to 53 to 60 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 81 near the shore to 70 to 79 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Kohala

Today: Windy. Mostly sunny with scattered showers. Highs around 82 near the shore to 71 to 80 near 3000 feet. East winds up to 30 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 63 to 72 near the shore to 53 to 60 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 81 near the shore to 70 to 79 near 3000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

South Big Island

Today: Sunny and windy. Highs around 87 near the shore to around 69 near 5000 feet. East winds 10 to 35 mph.

Tonight: Mostly clear. Breezy. Lows around 74 near the shore to around 50 near 5000 feet. East winds 10 to 25 mph.

Wednesday: Sunny and breezy. Highs around 87 near the shore to around 70 near 5000 feet. East winds 10 to 20 mph.

Puna

Today: Mostly cloudy with numerous showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 80 to 86 near the shore to 66 to 72 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Tonight: Partly cloudy with scattered showers. Lows 64 to 71 near the shore to 53 to 58 at 4000 feet. Northwest winds up to 15 mph. Chance of rain 40 percent.

Wednesday: Partly sunny with scattered showers. Highs 80 to 85 near the shore to 65 to 73 at 4000 feet. Southwest winds 10 to 15 mph shifting to the east in the afternoon. Chance of rain 40 percent.

Waikoloa

Today: Mostly sunny. Isolated showers in the afternoon. Highs around 87 near the shore to 65 to 75 above 4000 feet. South winds up to 15 mph shifting to the west in the afternoon. Chance of rain 20 percent.

Tonight: Mostly clear. Lows 70 to 75 near the shore to 47 to 55 above 4000 feet. Southeast winds up to 10 mph.

Wednesday: Sunny. Highs around 86 near the shore to 66 to 73 above 4000 feet. East winds 10 to 15 mph shifting to the northwest in the afternoon.

Detailed Forecast

Synopsis

The remnants of an old cold front will linger over the state today, bringing increased showers. Winds will veer southeasterly over the next couple of days and ease, especially over the smaller islands. Expect a return of locally strong trades this weekend.

Discussion

Radar and satellite imagery early this morning shows an extensive shower band draped across the island chain (the remnants of an old front), bringing numerous, yet beneficial, showers into windward areas, especially the smaller islands. Winds are still strong enough to carry appreciable amounts of rainfall over to interior and leeward areas as well. Rainfall totals have been heaviest over Kauai, with several areas receiving around a quarter to half of an inch in the last 6 hours, and 1 to 3 inches in the last 24 hours (Mt. Waialeale with 4.17 inches in past 24 hours). Oahu is beginning to catch up with generally a quarter to half of an inch in the last 24 hours for many windward and interior locations. High-res models continue to show this shower band gradually dissipating through this evening.
Global models have changed little in bringing a compact shortwave southward to near 30N and the Dateline, as it deepens and briefly closes off northwest of the islands around the middle of this week. Though the GFS solution is a bit weaker, both models depict the onset of surface pressure falls immediately west of the islands beginning tonight, which will weaken the background wind field and transition the trades to a locally breezy southeasterly flow. This will place the smaller islands in the shadow of the Big Island on Wednesday and possibly Thursday, with some combination of ESE winds over windward zones and sea breezes over some leeward slopes and coasts. The dry airmass, which was displaced off to the south and east of the state by the old front, will be pulled back northwestward over the state once again as winds veer southeasterly. This increases confidence that leeward areas will remain on the drier side for Wednesday and Thursday.
Beginning Thursday afternoon, the surface trough will weaken as it is absorbed into the trade wind belt and carried off to the west. A breezy easterly trade wind pattern will quickly reestablish over the islands on Friday, as a longwave ridge builds northeast of the area. In the longer term, the global models agree on a strong surface high building in far north of the state for the latter half of the weekend, which would tighten the pressure gradient over the islands and bring another round of locally strong and gusty trade winds.

Aviation

Moderate to locally windy trade winds will persist through at least afternoon, the result of strong high pressure to the northeast of the Islands. A strong trade wind inversion, sloping from 08 kft near Hilo to around 11 kft near Lihue, will keep the air mass over the state highly stable. AIRMET Tango for low level turbulence over and downwind of terrain remains in effect for all islands, but may be canceled later today for Kauai and Oahu.
As of 2 am, a broad band of quick moving showers could be seen on satellite stretched across Kauai, Oahu, and windward portions of the remaining islands. AIRMET Sierra for occasional mountain obscuration remains in effect for Kauai and Oahu. Conditions are expected to improve this afternoon once the band of showers weakens and shifts to the southwest.
Elsewhere across the state, VFR conditions will prevail. The inversion aloft will inhibit most shower activity east of Molokai. Occasionally cloudy but mostly dry conditions are expected across the Big Island and leeward Maui through twenty-four hours and beyond.

Marine

Recent fresh to locally strong trade winds will gradually decline through the day as robust, albeit weakening, surface high pressure passes about 1,000 nautical miles north of the islands. A Small Craft Advisory (SCA) is now in effect for all waters. As the surface high moves east, winds will further weaken and the SCA will be scaled back to the eastern island waters surrounding Big Island and Maui County from tonight through early Thursday. A surface trough developing a couple hundred miles west of Kauai will veer trades more east southeast Wednesday and Thursday, especially over the western end of the island chain. SCA-level winds should hold around Big Island and Maui the next several days. As the trough dissipates going into Friday, stronger east trades will likely once again expand west that will require an western expansion of the SCA. Generally, fresh to locally strong trades will occur this weekend.
The largest surf will be along east-facing shores the next couple of days. Recent buoy observations have strong trades over and upwind of the state producing short period (around 10 second) 8 to 9 foot seas. These large east wind waves will produce rough chop along eastern shores but surf should remain under High Surf Advisory criteria today. Rough eastern shore surf will subside back to near seasonal levels late today or Wednesday. Surf along north-facing shores will be below November averages through the week as a series of primarily small 3 to 4 foot, medium period north northwest swells (340-350 degree) move in. The latest swell peaked Monday and will decline through Wednesday, followed by a couple of overlapping north northwest swells from Thursday into the weekend. Small surf continues along south-facing shores.

Fire weather

Winds will slowly weaken from northwest to southeast through tonight. Marginal fire conditions are still possible over the windier portions of leeward Big Island through this afternoon.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST this evening for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Leeward Waters.
Small Craft Advisory until 6 AM HST Thursday for Maui County Windward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.

Big Island Now Weather is brought to you by Blue Hawaiian Helicopters.

Check out their Big Island Helicopter Tours today!

Data Courtesy of NOAA.gov