Hilo

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 81 near the shore to 64 to 71 at 4000 feet. North winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers. Lows 63 to 71 near the shore to around 55 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Tuesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 78 to 83 near the shore to 63 to 71 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Kona

Today: Sunny. Isolated showers in the afternoon. Highs around 85 near the shore to around 68 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers in the evening. Lows around 71 near the shore to around 54 near 5000 feet. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny. Scattered showers in the afternoon. Highs around 85 near the shore to around 69 near 5000 feet. Light winds. Chance of rain 40 percent.

Waimea

Today: Windy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 67 to 87. East winds 10 to 30 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 62 to 69 near the shore to 54 to 63 near 3000 feet. East winds 10 to 25 mph decreasing to 10 to 15 mph after midnight. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers. Highs 66 to 86. East winds 10 to 15 mph. Chance of rain 50 percent.

Kohala

Today: Windy. Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 67 to 87. East winds 10 to 30 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 62 to 69 near the shore to 54 to 63 near 3000 feet. East winds 10 to 25 mph decreasing to 10 to 15 mph after midnight. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers. Highs 66 to 86. East winds 10 to 15 mph. Chance of rain 50 percent.

South Big Island

Today: Sunny and windy. Isolated showers in the afternoon. Highs around 85 near the shore to around 67 near 5000 feet. East winds up to 30 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Breezy. Isolated showers in the evening. Lows around 73 near the shore to around 52 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Tuesday: Sunny and breezy. Isolated showers in the afternoon. Highs around 85 near the shore to around 69 near 5000 feet. East winds 10 to 20 mph. Chance of rain 20 percent.

Puna

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 81 near the shore to 64 to 71 at 4000 feet. North winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers. Lows 63 to 71 near the shore to around 55 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 70 percent.

Tuesday: Partly sunny. Numerous showers in the morning, then scattered showers in the afternoon. Highs 78 to 83 near the shore to 63 to 71 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 70 percent.

Waikoloa

Today: Sunny and windy. Highs 82 to 91 near the shore to 66 to 75 above 4000 feet. Northeast winds up to 30 mph.

Tonight: Mostly clear. Lows around 71 near the shore to 49 to 57 above 4000 feet. East winds up to 15 mph.

Tuesday: Sunny. Isolated showers in the afternoon. Highs 82 to 89 near the shore to 67 to 72 above 4000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Locally strong trades will deliver increased trade wind showers to windward slopes through mid-week, especially over central portions of the state. Trades and shower coverage then trend downward during the end of the week.

Discussion

Continuing locally strong around the southern periphery of surface high pressure is directing a remnant band of frontal showers toward the islands at press time. Readily evident last evening's visible imagery, the incoming shower band extends ENE toward toward 140W and is oriented roughly orthogonal to the island chain. The latest observational trends and modeling suggest the lion's share of this moisture will focus over central portions of the state through Tuesday with Kauai and the Big Island residing on the periphery. As a result, periods of increased clouds and showers are expected over windward and mauka sections of Oahu and Maui County during the next 48 hours or so, particularly overnight and lingering into the morning hours. With that said, persistent deep easterly flow will advect drier mid- level air around 700mb across the region at the same time. The arrival of this drier airmass aloft and the resultant increase in stability will result in a trade off between shower coverage and intensity where forecast pops can remain appropriately high but rainfall away from the most favored locales remain comparatively modest. The remnants of this band will be ushered WNW by the trades allowing a brief increase in showers for Kauai during mid- week.
The mid-week period will be characterized by additional slight weakening of trades as the expansive high that has dominated the circulation over the north central Pacific begins to lose its grip over the area. Some degree of upper-level troughing will be a fixture during the coming week as the jet nestled within its southern flank directs a steady dose of cirrus from the lower latitudes and into area skies. As has been the case during the last couple of days, cirrus will be mostly transparent but even batches of partially opaque high cloud will be sufficient to take the edge off of daytime heat. Locally breezy trades will deliver periods of trade wind showers to windward zones for the remainder of the week, but increased stability will help limit rainfall amounts.

Aviation

Strong easterly trade winds will prevail through the 24-hr forecast period, with clouds and showers favoring windward and mountain locations. MVFR CIGS/VSBYs are expected through the early morning hours over most windward areas, especially in and around passing showers.
AIRMET Sierra remains in effect for mountain obscuration across all windward zones due to clouds and showers. Conditions should improve through the late morning hours.
AIRMET Tango remains in effect for low-level mechanical turbulence leeward of mountains due to strong trades.

Marine

A strong (1034 mb) surface high pressure system will remain nearly stationary far N of the islands through the upcoming week. Currently, the tight pressure gradient S of the high is supporting fresh to strong trade winds that are reaching near- gale speeds in areas where terrain accelerates the flow. A Small Craft Advisory (SCA) is posted for all waters through this afternoon.
A couple of low pressure systems in the NE Pacific will gradually weaken the eastern periphery of the high over the next couple of days, weakening the gradient near and NE of the islands. Initially, the weakening gradient will still support fresh trade winds that will remain strong in the accelerated zones, where the SCA has been extended through Tuesday night. Further weakening is expected by midweek, with moderate to fresh trade winds prevailing. A trend toward stronger trade wind flow is expected toward the end of the week as the high builds eastward.
No significant swells are expected this week. The strong trades will support rough and choppy surf along E facing shores for the next several days, with a trend down thereafter as the upstream fetch diminishes. Minimal swell energy from the S and SE is expected for most of the week, but forecast models indicate long- period S swell will increase in about a week or so, from a developing fetch SE of New Zealand this week.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Wednesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
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 Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.

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Data Courtesy of NOAA.gov