West Side

Today: Breezy. Mostly sunny with isolated showers. Highs 80 to 86. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows 68 to 76. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Thursday: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 80 to 86. Northeast winds 10 to 20 mph. Chance of rain 30 percent.

South Side

Today: Sunny and breezy. Highs around 90. Northeast winds 10 to 20 mph.

Tonight: Partly cloudy. Breezy. Lows 69 to 76. Northeast winds 10 to 20 mph.

Thursday: Mostly sunny. Breezy. Highs around 89. Northeast winds 10 to 20 mph.

North Shore

Today: Breezy. Partly sunny with scattered showers. Highs 80 to 86 near the shore to around 67 near 5000 feet. East winds 10 to 20 mph decreasing to up to 20 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 73 near the shore to around 52 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 80 to 86 near the shore to around 67 near 5000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

Central Maui

Today: Mostly sunny. Breezy. Highs 81 to 90. Northeast winds 10 to 25 mph.

Tonight: Partly cloudy. Breezy. Lows around 71. Northeast winds 10 to 20 mph.

Thursday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 82 to 90. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 65 at the visitor center to around 70 at the summit. East winds up to 25 mph. Chance of rain 50 percent.

Tonight: Breezy. Partly cloudy with scattered showers. Lows around 49 at the visitor center to around 47 at the summit. East winds up to 20 mph. Chance of rain 50 percent.

Thursday: Mostly sunny with scattered showers. Highs around 65 at the visitor center to around 67 at the summit. East winds up to 15 mph. Chance of rain 50 percent.

East Maui

Today: Breezy. Partly sunny with scattered showers. Highs 80 to 86 near the shore to around 67 near 5000 feet. East winds 10 to 20 mph decreasing to up to 20 mph in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 73 near the shore to around 52 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Thursday: Breezy. Partly sunny with scattered showers. Highs 80 to 86 near the shore to around 67 near 5000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 50 percent.

Lanai City

Today: Sunny and breezy. Highs 74 to 82. Northeast winds 10 to 25 mph.

Tonight: Partly cloudy. Breezy. Lows 63 to 68. Northeast winds 15 to 25 mph.

Thursday: Sunny and breezy. Highs 74 to 82. Northeast winds 10 to 20 mph.

Kaunakakai

Today: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs 72 to 89. Northeast winds 15 to 25 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Lows 61 to 75. Northeast winds 15 to 20 mph.

Thursday: Mostly sunny. Breezy. Isolated showers in the morning. Highs 72 to 89. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

The high pressure ridge will remain in place north of the Hawaiian Islands into the first half of next week. Expect breezy trade winds today and tomorrow, becoming more moderate trade winds from Friday through Sunday, then moderate to breezy again from Monday onward. Weather wise very stable conditions persist for most of the week, with a slight increase in clouds and showers for windward mountain areas on Friday and Saturday. Stable weather conditions return from Sunday onward as an upper level ridge builds over the region.

Discussion

The subtropical ridge will remain in place north of the Hawaiian Islands through the first half of next week. Easterly trade winds will start off in the moderate to breezy range through Thursday, then drop slightly back to more moderate ranges from Friday through Sunday, and finally increase back into the moderate to locally breezy range from next week Monday onward. Satellite imagery this morning shows an extensive blanket of stable stratocumulus clouds in the upstream trade wind flow. These stable clouds are capped by a strong 5,000 foot subsidence temperature inversion, limiting vertical cloud development and keeping drier conditions in the forecast through Thursday.
In this summer trade wind weather pattern we look for subtle changes in the forecast guidance to pick out slight day to day or island by island changes. One of those slight changes starts on Friday morning as our confidence grows that divergence between an upper level trough the subtropical jet stream will combine forces with a weak low level trough riding into the islands on the trade winds. This combination of upper level and low level forcing will lift the temperature inversion heights to around the 7,000 foot range, slightly increasing passing rainfall activity into the scattered to numerous range, mainly over windward and mountain areas in the overnight to early morning hours. High level cirrus clouds will develop over all islands in this weather pattern, courtesy of the subtropical jet. Not much in the way of rainfall totals are expected in the Friday and Saturday time period, probably less than 0.10 inch over a 12 hour overnight time period for most windward mountain locations and up to 0.50 inch amounts for the terrain favored wettest locations.
Stable summertime weather conditions predictably return by Sunday as a high pressure ridge builds directly over the Hawaii Region. This ridge aloft will increase downward vertical motions (subsidence) effectively lowering the temperature inversion heights back down to around the 5,000 foot elevation level and severely limiting shower opportunities from Sunday onward.

Aviation

A high pressure ridge remains in place north of the Hawaiian Islands this week. Moderate to breezy easterly trade winds remain in the forecast. Weather conditions will remain on the stable side through Thursday with limited clouds and showers.
No AIRMETs currently in effect. AIRMET Tango may be needed later today for moderate low level turbulence over and south through west of island mountains as wind speeds increase over these higher terrain features.

Marine

High pressure will remain far northeast of the state throughout the week. Fresh to locally strong trades will likely persist through most of the week, although we could see wind speeds drop slightly as a weak trough develops near the western end of the state into the weekend. A Small Craft Advisory (SCA) is in effect for the typical windy areas around Maui County and the Big Island through Thursday night.
A short-period south-southeast swell will continue to fill in today, slowing the decline of surf heights through Friday. Another small increase is expected heading into the weekend as a new long- period southwest swell arrives from the Tasman Sea.
Surf along east facing shores will continue to remain rough and choppy with a slight boost in surf heights expected through mid week as the trades strengthen and again late this week into the weekend as a short-period northeast swell fills in. Surf along north facing shores will continue to decline through Wednesday and remain nearly flat through the weekend.

Fire weather

Trade winds will remain in the moderate to locally breezy range through the forecast period. Shower trends may increase from Friday morning into Saturday night as a combination of upper and low level disturbances move into the islands. Drier and more stable weather returns from Sunday on into the middle of next week with borderline fire weather concerns over leeward areas.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Thursday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov