Photo Credit: James Grenz

Hilo

Today: Cloudy with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 76 to 82 near the shore to 64 to 69 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 60 to 67 near the shore to 51 to 56 at 4000 feet. Northwest winds up to 15 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 76 to 82 near the shore to 64 to 71 at 4000 feet. Northeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Kona

Today: Mostly sunny in the morning then becoming mostly cloudy. Isolated showers. Highs 80 to 86 near the shore to around 67 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming partly cloudy. Isolated showers. Lows 66 to 72 near the shore to 44 to 53 near 5000 feet. Light winds. Chance of rain 20 percent.

Wednesday: Mostly sunny in the morning then becoming mostly cloudy. Isolated showers. Highs around 83 near the shore to around 67 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Waimea

Today: Breezy. Mostly cloudy with isolated showers. Highs 64 to 83. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming mostly clear. Breezy. Isolated showers. Lows around 61 near the shore to 50 to 59 near 3000 feet. East winds up to 25 mph with gusts to 45 mph. Chance of rain 20 percent.

Wednesday: Breezy. Mostly sunny with isolated showers. Highs 64 to 83. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Gusts up to 45 mph. Chance of rain 20 percent.

Kohala

Today: Breezy. Mostly cloudy with isolated showers. Highs 64 to 83. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming mostly clear. Breezy. Isolated showers. Lows around 61 near the shore to 50 to 59 near 3000 feet. East winds up to 25 mph with gusts to 45 mph. Chance of rain 20 percent.

Wednesday: Breezy. Mostly sunny with isolated showers. Highs 64 to 83. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Gusts up to 45 mph. Chance of rain 20 percent.

South Big Island

Today: Mostly sunny in the morning then becoming partly sunny. Breezy. Highs around 81 near the shore to around 67 near 5000 feet. East winds up to 25 mph.

Tonight: Partly cloudy. Breezy. Lows around 69 near the shore to around 47 near 5000 feet. Northeast winds up to 20 mph increasing to 10 to 20 mph after midnight.

Wednesday: Mostly sunny in the morning then becoming partly sunny. Breezy. Highs around 81 near the shore to around 67 near 5000 feet. East winds up to 25 mph.

Puna

Today: Cloudy with scattered showers in the morning, then partly sunny with isolated showers in the afternoon. Highs 76 to 82 near the shore to 64 to 69 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Cloudy in the evening then becoming partly cloudy. Scattered showers. Lows 60 to 67 near the shore to 51 to 56 at 4000 feet. Northwest winds up to 15 mph. Chance of rain 50 percent.

Wednesday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 76 to 82 near the shore to 64 to 71 at 4000 feet. Northeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 50 percent.

Waikoloa

Today: Sunny in the morning then becoming partly sunny. Breezy. Highs 79 to 86 near the shore to 65 to 70 above 4000 feet. Northeast winds up to 25 mph.

Tonight: Partly cloudy. Breezy. Lows 63 to 72 near the shore to 44 to 53 above 4000 feet. Southeast winds up to 25 mph with gusts to 45 mph.

Wednesday: Mostly sunny. Breezy. Highs 78 to 85 near the shore to 65 to 70 above 4000 feet. East winds up to 25 mph shifting to the north 10 to 25 mph in the afternoon.

Detailed Forecast

Synopsis

Dry, breezy easterly trades will build across the state today and will persist through the week. The bulk of low clouds and any shower activity will be focused over windward and mauka areas during this time.

Discussion

A strong zonal Pacific jet will force persistent ridging over the northeast Pacific basin for the balance of the week which will in turn favor upstream pressure rises in maintenance of local trade wind weather. At press time, a band of increased convergence exists near Oahu in the Kauai Channel along the interface of existing NNE winds and building easterly trades. The attendant greater coverage of clouds and showers, a few locally heavy, will be ushered westward during the next 6 to 9 hours or so, departing to the waters west of Kauai by midday. The latest CIMSS PWAT product offers observational evidence in support the latest modeling that the coming period of breezy trades will reside firmly on the drier side of climatology as mid-level ridging suppresses inversion heights to around 5kft or lower. Afternoon convection over interior and leeward sections of the Big Island will likewise be suppressed this week with nothing more than scattered light afternoon showers expected courtesy of rapidly diminishing mid- level moisture. There is at least an outside chance for an isolated heavy shower over interior Big Island this afternoon, similar to yesterday when cloud tops reached around 25kft over the southeast-facing slopes of Mauna Loa. However, even as mid-level lapse rates steepen slightly in response to an approaching upper trough axis, any gains in the temperature profile will likely be offset by the rapid decrease in mid-level moisture supply. As such, the Big Island's convective response is still expected to be muted. Trades will hover within or near the breezy category into the weekend and will tend to be strongest over the eastern end of the state.

Aviation

A return of moderate to breezy easterly trades is expected statewide today as a trough shifts westward and diminishes and high pressure builds to the north. Although VFR conditions will prevail for most locations through the 24-hr TAF period, spotty windward showers will lead to brief periods of MVFR CIGS/VSBYS, especially through the morning hours.
AIRMET Sierra for MTN TEMPO OBSC remains in effect for windward Oahu, but should be lifted later this morning as conditions improve.
AIRMET Tango remains in effect for moderate turb above FL250 over the western end of the state and will likely shift over the eastern end of the state later today.

Marine

A weak low level trough just north of the area will keep some northeast winds near Kauai and east winds from Oahu eastward. More typical trade winds will become reestablished by Tuesday afternoon and will strengthen through Wednesday as high pressure builds in to our north. A Small Craft Advisory is in effect for waters around Maui County and the Big Island through Thursday. The SCA will likely be expanded and extended Thursday into the weekend as seas build due to large west- northwest swell. A slight decrease in trade wind speeds are expected Friday as the high becomes centered far northeast of the area.
A small northwest swell has reach near shore buoys and will continue to fill today and peak tonight into Wednesday before slowly subsiding.
A much larger, and rather long period, west-northwest swell is expected to fill in Thursday, peak Thursday night and early Friday before lowering gradually over the weekend. A recent scatterometer pass shows are large area of winds of 50 knots or greater aimed at the Hawaiian Island Archipelago. Also a recent satellite altimeter pass showed seas as high as 50 feet near the core of these winds. This wave height is several feet higher than model guidance thus we expect the swell height to be higher than model guidance once it reaches the main Hawaiian Islands. This swell will easily reach warning levels along most north and west facing shores during the peak of the swell. Also due to the westerly direction of the swell, warning level surf is likely along the Kona coast of the Big Island. The timing of rising surf and high tides cycles during the late evening hours on Thursday and Friday may cause significant overwash for low- lying coastal areas.
Small, mainly background south swells are expected through the week and into the weekend. Short period choppy surf will gradually pick up today and remain elevated Wednesday into the weekend as trade winds strengthen over and upwind of the state.

HFO Watches/Warnings/Advisories

Small Craft Advisory from 6 AM this morning to 6 PM HST Thursday for Maui County Windward Waters, Maui County Leeward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov