Photo Credit: Tyler Rooke

West Side

Today: Sunny and windy. Isolated showers in the morning. Highs 79 to 86. East winds 15 to 30 mph. Chance of rain 20 percent.

Tonight: Breezy. Mostly clear with isolated showers in the evening, then mostly cloudy with scattered showers after midnight. Lows 67 to 75. East winds up to 25 mph decreasing to up to 15 mph after midnight. Chance of rain 50 percent.

Thursday: Breezy. Mostly sunny with isolated showers. Highs 81 to 87. East winds 10 to 20 mph. Chance of rain 20 percent.

South Side

Today: Sunny and windy. Highs around 88. Northeast winds 10 to 30 mph decreasing to up to 30 mph in the afternoon.

Tonight: Partly cloudy. Isolated showers after midnight. Lows 66 to 75. North winds up to 15 mph. Chance of rain 20 percent.

Thursday: Sunny and breezy. Highs around 89. North winds 10 to 25 mph.

North Shore

Today: Breezy. Partly sunny with numerous showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 78 to 83 near the shore to around 66 near 5000 feet. Southeast winds up to 25 mph shifting to the east 10 to 25 mph in the afternoon. Chance of rain 60 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then frequent showers after midnight. Lows around 72 near the shore to around 52 near 5000 feet. Southeast winds 10 to 20 mph. Chance of rain 90 percent.

Thursday: Mostly cloudy. Breezy. Frequent showers in the morning, then numerous showers in the afternoon. Highs 79 to 84 near the shore to around 67 near 5000 feet. East winds 10 to 20 mph. Chance of rain 90 percent.

Central Maui

Today: Sunny and windy. Highs 81 to 88. East winds 10 to 30 mph.

Tonight: Breezy. Mostly clear in the evening, then mostly cloudy with scattered showers after midnight. Lows 67 to 72. East winds 10 to 20 mph. Chance of rain 50 percent.

Thursday: Breezy. Mostly sunny with isolated showers. Highs 82 to 90. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

Upcountry

Today: Mostly sunny. Windy. Scattered showers in the morning. Isolated showers late in the afternoon. Highs around 63 at the visitor center to around 70 at the summit. East winds up to 30 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers in the evening, then mostly cloudy with isolated showers after midnight. Lows 44 to 54. Southeast winds 10 to 15 mph. Chance of rain 50 percent.

Thursday: Mostly sunny with scattered showers. Highs around 62 at the visitor center to around 67 at the summit. Southeast winds up to 15 mph. Chance of rain 50 percent.

East Maui

Today: Breezy. Partly sunny with numerous showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 78 to 83 near the shore to around 66 near 5000 feet. Southeast winds up to 25 mph shifting to the east 10 to 25 mph in the afternoon. Chance of rain 60 percent.

Tonight: Mostly cloudy. Breezy. Scattered showers in the evening, then frequent showers after midnight. Lows around 72 near the shore to around 52 near 5000 feet. Southeast winds 10 to 20 mph. Chance of rain 90 percent.

Thursday: Mostly cloudy. Breezy. Frequent showers in the morning, then numerous showers in the afternoon. Highs 79 to 84 near the shore to around 67 near 5000 feet. East winds 10 to 20 mph. Chance of rain 90 percent.

Lanai City

Today: Sunny and breezy. Highs 74 to 81. Northeast winds 10 to 20 mph.

Tonight: Mostly clear. Isolated showers after midnight. Lows around 65. Northeast winds up to 15 mph. Chance of rain 20 percent.

Thursday: Sunny. Highs 74 to 83. East winds around 10 mph.

Kaunakakai

Today: Sunny and breezy. Highs 70 to 89. East winds 15 to 20 mph.

Tonight: Partly cloudy. Breezy. Isolated showers after midnight. Lows 59 to 75. East winds 10 to 20 mph. Chance of rain 20 percent.

Thursday: Sunny. Isolated showers in the afternoon. Highs 72 to 90. East winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Gusty trade winds, low relative humidity, and dry fuels will result in fire weather concerns from late this morning through the afternoon across leeward sections of all islands today. Otherwise, brief clouds and showers will favor mainly windward areas. Showers are expected to increase tonight through Friday night as a mid-level trough moves through. Winds will also taper off Thursday night into Friday. A drier trend is expected this weekend with strengthening trade winds.

Discussion

Broad ridging north and northeast of the islands will continue to produce locally strong trade winds across the islands today. Although winds will be similar or slightly weaker than yesterday for most locations, slightly drier air is anticipated to settle over the islands, allowing relative humidity values to dip into Red Flag Warning criteria. See the Fire Weather section below for details. Also of note, the strong advisory-level winds that were observed across the Big Island summits yesterday afternoon and evening have sharply declined overnight. Therefore, the Wind Advisory for Big Island summits has been cancelled with this morning's forecast updates.
Early morning 12z soundings from Lihue and Hilo showed strong trade wind inversions between 7,000 and 9,000 feet. Trades will carry brief clouds and showers into the islands today, focusing mainly over windward and mauka areas. However, guidance indicates that conditions are expected to be generally stable over the state today, limiting rainfall amounts in most locations.
A mid-level trough will move over windward and southeast Big Island tonight, then spread westward during the second half of the week. This feature will bring an increase in clouds and showers through Friday night. A weak upper level low moving into position northeast of the state during this time may also enhance the incoming showers.
An advancing cold front well north of Hawaii will displace the driving high pressure further northeast of the islands, slightly weakening wind speeds by Thursday night. Meanwhile, a nearly stationary low pressure system will set up northwest of Hawaii. The pressure gradient between these two features will continue to maintain moderate and slightly veered east southeasterly winds into Friday. Island terrain blockage under this wind regime will further weaken the winds across leeward areas, resulting in localized sea breezes and interior clouds Friday afternoon before the trade winds re-strengthen this weekend.
The forecast will trend drier with a continuation of the moderate east southeast flow from Saturday into the middle of next week.

Aviation

Breezy easterly trade winds will prevail during the next 24 hours, with limited low clouds and showers focusing mainly over windward and mountain areas. Predominantly VFR conditions are expected.
AIRMET Tango remains in effect for moderate low-level turbulence over and downwind of the island terrain. This AIRMET will likely be needed through this evening.

Marine

The high pressure ridge north of the island will producing fresh to strong trade winds today with the strongest winds reaching near gale conditions in the windiest eastern channels. The Small Craft Advisory (SCA) remains in effect for the central and eastern waters through tonight. This SCA will then decrease in coverage on Thursday. Trade wind speeds will fall below SCA conditions by Thursday night as the ridge weakens north of the island chain.
The current north (350) medium period swell will continue to slowly decrease just below High Surf Advisory (HSA) thresholds this morning. Therefore, the HSA for north facing shores was cancelled. Surf heights will remain elevated at just below advisory surf height thresholds through the morning hours. Surf along west facing shores remains slightly elevated with wrap around north swell energy lingering for into Thursday.
Surf heights along east shores will remain elevated tonight in response to short period trade wind swell over and upstream of the islands. East shore surf heights will then decline on Thursday as trade wind speeds weaken. South shore surf will remain small this week mainly due to south and southeast background swells into next week. The next small long period south swell pulse will arrive in Hawaii from Friday into Saturday.

Fire weather

A combination of gusty winds, relatively stable and dry conditions, and dry fuels (with Keetch-Byram Drought Index (KBDI) values well over 600) will result in critical fire weather conditions today. A Red Flag Warning has been issued for leeward sections of all the islands from late morning through the afternoon, when relative humidity will be at its lowest and winds will be maximized. As a mid-level trough and upper low nears the eastern end of the state tonight and winds gradually begin to weaken, expect fire weather concerns to diminish for the rest of the week.

HFO Watches/Warnings/Advisories

Red Flag Warning from 10 AM this morning to 6 PM HST this evening for HIZ301, HIZ304, HIZ305, HIZ307, HIZ308, HIZ309, HIZ310, HIZ311, HIZ315, HIZ316, HIZ320, HIZ321, HIZ322, HIZ323, HIZ324, HIZ325, HIZ328, HIZ329, HIZ330, HIZ333, HIZ334, HIZ337, HIZ338, HIZ341, HIZ342.
Small Craft Advisory until 6 AM HST Thursday for Oahu Leeward Waters, Kaiwi Channel, 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