Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 78 near the shore to around 63 at 4000 feet. West winds up to 15 mph shifting to the east in the afternoon. Chance of rain 50 percent.
Tonight: Mostly cloudy with scattered showers. Lows 59 to 66 near the shore to around 51 at 4000 feet. South winds up to 10 mph shifting to the west after midnight. Chance of rain 50 percent.
Wednesday: Mostly cloudy with numerous showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs around 78 near the shore to around 64 at 4000 feet. Southeast winds up to 15 mph shifting to the east in the afternoon. Gusts up to 35 mph. Chance of rain 70 percent.
Kona
Today: Mostly sunny. Isolated showers in the afternoon. Highs around 83 near the shore to around 67 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.
Tonight: Partly cloudy with isolated showers. Lows around 67 near the shore to 42 to 49 near 5000 feet. Light winds. Chance of rain 20 percent.
ARTICLE CONTINUES BELOW AD
ARTICLE CONTINUES BELOW AD
Wednesday: Mostly sunny. Scattered showers in the afternoon. Highs around 83 near the shore to around 66 near 5000 feet. West winds up to 10 mph. Chance of rain 40 percent.
Waimea
Today: Breezy. Mostly sunny with isolated showers. Highs around 76 near the shore to 66 to 74 near 3000 feet. East winds up to 25 mph. Chance of rain 20 percent.
Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 58 to 67 near the shore to 49 to 56 near 3000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.
Wednesday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 76 near the shore to 66 to 74 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.
Kohala
Today: Breezy. Mostly sunny with isolated showers. Highs around 76 near the shore to 66 to 74 near 3000 feet. East winds up to 25 mph. Chance of rain 20 percent.
ARTICLE CONTINUES BELOW AD
Tonight: Partly cloudy with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 58 to 67 near the shore to 49 to 56 near 3000 feet. Southeast winds up to 15 mph. Chance of rain 50 percent.
Wednesday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 76 near the shore to 66 to 74 near 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.
South Big Island
Today: Mostly sunny. Breezy. Highs around 81 near the shore to around 65 near 5000 feet. East winds up to 25 mph.
Tonight: Partly cloudy. Breezy. Lows around 68 near the shore to around 46 near 5000 feet. Northeast winds up to 25 mph becoming 10 to 20 mph after midnight.
Wednesday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 81 near the shore to around 65 near 5000 feet. East winds up to 25 mph. Chance of rain 20 percent.
Puna
ARTICLE CONTINUES BELOW AD
Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs around 78 near the shore to around 63 at 4000 feet. West winds up to 15 mph shifting to the east in the afternoon. Chance of rain 50 percent.
Tonight: Mostly cloudy with scattered showers. Lows 59 to 66 near the shore to around 51 at 4000 feet. South winds up to 10 mph shifting to the west after midnight. Chance of rain 50 percent.
Wednesday: Mostly cloudy with numerous showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs around 78 near the shore to around 64 at 4000 feet. Southeast winds up to 15 mph shifting to the east in the afternoon. Gusts up to 35 mph. Chance of rain 70 percent.
Waikoloa
Today: Sunny. Highs around 82 near the shore to 63 to 69 above 4000 feet. Southeast winds up to 15 mph shifting to the northwest in the afternoon. Gusts up to 35 mph.
Tonight: Partly cloudy. Lows 66 to 71 near the shore to 44 to 50 above 4000 feet. Southeast winds up to 10 mph.
Wednesday: Mostly sunny. Isolated showers in the afternoon. Highs around 82 near the shore to 62 to 69 above 4000 feet. South winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 20 percent.
Detailed Forecast
Synopsis
A high pressure system passing eastward, north of the state, will produce moderate to breezy trade winds into Wednesday. An approaching cold front will shift these winds from a more east to southeast direction from Wednesday afternoon into the weekend. A passing upper level low/trough will likely produce some rain shower enhancement across all islands on Friday and Saturday, favoring the overnight hours. All slopes of the Big Island should see a small boost in rainfall activity for the same time period. Expect wet weather trends starting early next week as a trailing cold front sweeps into Hawaiian waters.
Discussion
The satellite picture this morning starts with upper level water vapor imagery, where a weak upper trough near the Big Island continues to slowly drift eastward away from the islands. Infra-red imagery shows a few fairly stable cloud bands just upstream of the islands riding in on the easterly trade winds. Scattered showers will continue to develop mainly over windward and mountain areas through the early morning hours. Drier trends are forecast for most of the daylight hours.
A high pressure system northeast of the Hawaiian Islands will continue to drift eastward away from the state over the next few days. Expect moderate to breezy trade winds to peak today and then decrease as the high center drifts farther away from the islands from Wednesday onward. A cold frontal system approaching the islands from the northwest will cause the ridge to lift and weaken just north of the state. This change in surface pressure patterns will produce a trend to southeasterly winds over the western islands with east to southeast winds near the Big Island and Maui. Typically these southeasterly winds are drier for all the smaller islands falling into the leeward rain shadow of the Big Island mountains. However, shower activity will pick up a bit along the east to southeast slopes of the Big Island as winds drive available tropical moisture up the mountain slopes near the Ka'u and Puna Districts on the Big Island.
On Thursday, a cold front will approach the state from the northwest, the forward motion on this weakening front will stall out far to the northwest of Kauai in the latest operational model runs. A trapped cold pool south of the subtropical ridge will form a cut off low pressure system just west of Kauai. This upper low will then sweep across the islands from west to east on Friday and Saturday, unstable conditions under this cold core low will briefly increasing shower trends across the state. The continued east to southeasterly wind flow pattern will likely limit these showers to windward slopes of Kauai, Oahu, Molokai, and Maui. However, a boost in island wide shower trends are likely for the Big Island as leeward sea breezes and windward trade winds produce enough upslope forcing for brief periods of shower activity in the Friday and Saturday afternoon to early evening hours.
In the extended range forecast for early next week, we continue to see the potential for more wet weather riding into the Hawaii Region on the tail end of a passing cold front. Model solutions at this range tend to struggle with the details from run to run. We are taking a blended model approach to reduce the errors. Look for increasing rainfall trends at this point with moderate confidence. Island by island weather impacts for early next week will evolve over time, stay tuned for updates as the forecast time period grows shorter.
Aviation
Moderate to breezy easterly trade winds will prevail today through tomorrow as high pressure to the north of the state moves eastward. A relatively dry and stable airmass will limit shower activity, with only isolated to scattered light showers favoring windward and mauka areas. VFR conditions will prevail, except for within passing showers.
AIRMET Tango for tempo moderate mechanical turbulence lee of the island terrain is in effect this morning. This AIRMET will likely need to remain in effect through today.
Marine
Fresh to strong easterly trades will continue today, then gradually shift out of the east-southeast tonight through midweek due to a weakness forming in the ridge to the north. Although the winds will ease into the light to moderate range over the western end of the state during this transition, expect the strong winds to hold over the windier waters around Maui County and the Big Island. The Small Craft Advisory has been expanded to account for this by including the Big Island and Maui Windward waters where accelerations typically occur with this wind direction. Guidance remains in decent agreement and shows this wind pattern holding into the upcoming weekend as a couple of fronts pass far north of the islands.
Surf along exposed north and west facing shores will hold near the seasonal average through Wednesday (another northwest pulse arriving tonight), then trend back up to advisory levels late Wednesday night into Thursday as a fresh, long-period northwest swell arrives from a hurricane-force system centered around 1700 nm to the northwest this morning. Recent satellite data showed a large area of gale- to storm-force northwest winds associated with this system focused at the islands within the 310-330 degree directional bands. SOFAR drifter buoys reflected this with seas near the center of the fetch coming in around or just over 30 ft, which is near predicted levels. This swell will hold around the advisory levels Friday as it moves through, then slowly ease over the weekend.
Surf along east facing shores will steadily climb through the week due to a combination of the trades locally and the upstream trade wind belt expanding with fresh to strong breezes.
HFO Watches/Warnings/Advisories
Small Craft Advisory until 6 PM HST Wednesday for Maui County Windward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.
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