Hilo

Tonight: Partly cloudy. Isolated showers in the evening. Lows 58 to 65 near the shore to around 49 at 4000 feet. Light winds becoming southwest up to 10 mph after midnight. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers. Highs 77 to 82 near the shore to 64 to 69 at 4000 feet. Southwest winds up to 10 mph shifting to the east in the afternoon. Chance of rain 20 percent.

Monday Night: Mostly cloudy with isolated showers. Lows 60 to 66 near the shore to 48 to 53 at 4000 feet. Light winds. Chance of rain 20 percent.

Kona

Tonight: Partly cloudy. Lows around 67 near the shore to 41 to 48 near 5000 feet. Light winds.

Monday: Mostly sunny. Isolated showers in the afternoon. Highs 81 to 86 near the shore to around 68 near 5000 feet. Light winds. Chance of rain 20 percent.

Monday Night: Partly cloudy. Isolated showers in the evening. Lows around 68 near the shore to 43 to 50 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Tonight: Partly cloudy. Lows 58 to 66 near the shore to 50 to 55 near 3000 feet. East winds up to 10 mph in the evening becoming light.

Monday: Mostly sunny. Isolated showers in the afternoon. Highs 62 to 82. Light winds. Chance of rain 20 percent.

Monday Night: Partly cloudy. Isolated showers in the evening. Lows 59 to 66 near the shore to 51 to 57 near 3000 feet. Light winds. Chance of rain 20 percent.

Kohala

Tonight: Partly cloudy. Lows 58 to 66 near the shore to 50 to 55 near 3000 feet. East winds up to 10 mph in the evening becoming light.

Monday: Mostly sunny. Isolated showers in the afternoon. Highs 62 to 82. Light winds. Chance of rain 20 percent.

Monday Night: Partly cloudy. Isolated showers in the evening. Lows 59 to 66 near the shore to 51 to 57 near 3000 feet. Light winds. Chance of rain 20 percent.

South Big Island

Tonight: Mostly clear. Lows around 67 near the shore to around 45 near 5000 feet. East winds up to 10 mph.

Monday: Mostly sunny. Isolated showers in the afternoon. Highs around 84 near the shore to around 66 near 5000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Monday Night: Partly cloudy. Isolated showers in the evening. Lows around 69 near the shore to around 47 near 5000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Puna

Tonight: Partly cloudy. Isolated showers in the evening. Lows 58 to 65 near the shore to around 49 at 4000 feet. Light winds becoming southwest up to 10 mph after midnight. Chance of rain 20 percent.

Monday: Mostly sunny with isolated showers. Highs 77 to 82 near the shore to 64 to 69 at 4000 feet. Southwest winds up to 10 mph shifting to the east in the afternoon. Chance of rain 20 percent.

Monday Night: Mostly cloudy with isolated showers. Lows 60 to 66 near the shore to 48 to 53 at 4000 feet. Light winds. Chance of rain 20 percent.

Waikoloa

Tonight: Mostly clear. Lows around 68 near the shore to 45 to 50 above 4000 feet. Light winds.

Monday: Mostly sunny. Isolated showers in the afternoon. Highs 81 to 87 near the shore to 64 to 71 above 4000 feet. Light winds. Chance of rain 20 percent.

Monday Night: Partly cloudy. Isolated showers in the evening. Lows around 69 near the shore to 46 to 51 above 4000 feet. Light winds. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Lighter large-scale winds will allow land and sea breezes to occur over all islands for the next few days. Expect fairly dry and stable conditions through Wednesday, with low clouds and a few light showers each afternoon favoring island interior and mountain areas. Rainfall trends will increase Thursday into Friday as a weak cold front moves through then stalls near Maui. Periods of passing showers and moderate to locally breezy trades will linger into next weekend.

Discussion

Light southeasterly winds are in place today. Afternoon visible satellite imagery shows scattered to broken clouds over island interiors as a result of sea breeze development, while isolated stable clouds drift over the waters. The afternoon balloon soundings from Lihue and Hilo show strong temperature inversions around 5000 feet, signifying very stable conditions. Precipitable water values are in the 0.9 to 1 inch range, still well below the average of around 1.25 inches for this time of year.
The upper-level subtropical ridge axis will linger just south of the state through Wednesday keeping these stable conditions in the forecast to go along with the light winds. Therefore, expect clouds and a few light showers to develop by late morning/afternoon over island mountain and interior sections each day as the sea breezes kick in, followed by clearing in the overnight hours with the land breezes. Rainfall amounts will remain on the lighter side due to the large-scale atmospheric stability and dry air in place.
By Thursday, long-range model guidance continues to show a shallow cold front creeping into the western islands from the northwest. Widespread showers and breezy trade winds will develop along the weakening frontal boundary as it passes through each island. The latest guidance continues to show this frontal cloud and shower band stalling out near Maui by Friday morning. All islands will benefit from a period of enhanced showers with this feature, especially along the windward and mountain slopes. The front will then break apart by Friday afternoon, with remnant unstable cloud/shower bands drifting into the islands on the strengthening easterly trade winds through much of next weekend.

Aviation

Light southeast background flow will allow afternoon sea breezes and interior clouds through the late afternoon followed by land breezes and clearing for most of the islands tonight. Brief mountain obscurations may occur around the cloud build ups, but VFR conditions will prevail with no AIRMETs are in effect or anticipated tonight. Monday will follow a similar diurnal pattern except for around Kauai where gentle to locally moderate south to southwest winds will strengthen.

Marine

Light background flow has shifted to become predominately southeasterly today. As a front approaches from the northwest over the next couple of days, gentle south to southeast winds will remain in place through Wednesday. Northeasterly trades will return during the second half of the week as a shallow cold front moves through.
The current northwest (310-320) swell continues to slowly decline, and surf and buoy observations show that surf heights along north and west facing shores have fallen below advisory levels. Therefore, the High Surf Advisory (HSA) was allowed to expire at noon today. We will see additional boosts in surf along north and west facing shores throughout the week, however. Guidance indicates the first in a series of overlapping northwest swells will begin arriving late Monday. An additional reinforcement is expected Tuesday. A couple of larger boosts in north shore surf will come later in the week Wednesday night through Thursday and again Friday night into Saturday.
Surf along south facing shores will continue to see a slight boost for the next couple of days from a series of consecutive southwest pulses. Small to moderate south shore surf can be expected before gradually declining through Wednesday. An additional south pulse is expected next weekend.
Surf along east facing shores will decline and then remain small for the rest of the week as a lingering small north-northeast swell fades through Monday.

Fire weather

Critical fire weather conditions are not expected through next week, as winds will remain light into Thursday morning. Daytime relative humidity may briefly touch critical levels over the drier leeward areas into early next week. However, increasing moisture and rainfall trends will develop Thursday into next weekend as a weakening cold front moves down the island chain, then stalls and breaks up near Maui.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov