Photo Credit: Tyler Rooke

West Side

Today: Isolated showers after noon. Partly sunny, with a high near 79. Breezy, with an east wind 7 to 12 mph increasing to 13 to 18 mph in the afternoon. Winds could gust as high as 25 mph. Chance of precipitation is 20%.

Tonight: Partly cloudy, with a low around 66. Breezy, with an east northeast wind 18 to 20 mph, with gusts as high as 28 mph.

Thursday: Isolated showers. Mostly sunny, with a high near 81. Breezy, with an east northeast wind 17 to 22 mph decreasing to 9 to 14 mph in the afternoon. Winds could gust as high as 31 mph. Chance of precipitation is 20%.

South Side

Today: Partly sunny, with a high near 79. Light and variable wind becoming west around 5 mph.

Tonight: Partly cloudy, with a low around 64. Light and variable wind.

Thursday: Isolated showers. Mostly sunny, with a high near 81. Light and variable wind becoming northeast 6 to 11 mph in the afternoon. Chance of precipitation is 20%.

North Shore

Today: Scattered showers. Partly sunny, with a high near 77. Windy, with an east wind 17 to 23 mph, with gusts as high as 32 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 65. Breezy, with an east wind 16 to 22 mph, with gusts as high as 31 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Thursday: Scattered showers. Partly sunny, with a high near 79. Windy, with an east wind 15 to 23 mph, with gusts as high as 32 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Central Maui

Today: Scattered showers, mainly after noon. Partly sunny, with a high near 77. Breezy, with an east northeast wind 9 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Partly cloudy, with a low around 63. Breezy, with an east northeast wind 10 to 16 mph, with gusts as high as 22 mph.

Thursday: Scattered showers. Partly sunny, with a high near 79. Breezy, with an east northeast wind 13 to 20 mph, with gusts as high as 28 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Upcountry

Today: Partly sunny, with a high near 64. Light and variable wind becoming west around 6 mph.

Tonight: Partly cloudy, with a low around 53. Light east southeast wind.

Thursday: Isolated showers. Mostly sunny, with a high near 66. Light and variable wind becoming east 8 to 13 mph in the afternoon. Chance of precipitation is 20%.

East Maui

Today: Showers likely. Mostly cloudy, with a high near 75. East wind 7 to 9 mph. Chance of precipitation is 70%. New precipitation amounts between a quarter and half of an inch possible.

Tonight: Showers likely. Mostly cloudy, with a low around 61. East wind 8 to 11 mph. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

Thursday: Scattered showers. Partly sunny, with a high near 77. East wind 11 to 14 mph, with gusts as high as 18 mph. Chance of precipitation is 50%. New precipitation amounts between a tenth and quarter of an inch possible.

Lanai City

Today: Isolated showers before noon. Sunny, with a high near 72. Breezy, with a light northeast wind increasing to 10 to 15 mph in the afternoon. Winds could gust as high as 21 mph. Chance of precipitation is 20%.

Tonight: Mostly clear, with a low around 62. Breezy, with a northeast wind 15 to 17 mph, with gusts as high as 24 mph.

Thursday: Scattered showers. Partly sunny, with a high near 74. Breezy, with a northeast wind 9 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 30%. New precipitation amounts between a tenth and quarter of an inch possible.

Kaunakakai

Today: Isolated showers after noon. Mostly sunny, with a high near 77. East wind 7 to 13 mph. Chance of precipitation is 20%.

Tonight: Mostly clear, with a low around 67. East northeast wind around 14 mph, with gusts as high as 18 mph.

Thursday: Isolated showers. Mostly sunny, with a high near 79. Breezy, with an east northeast wind 13 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 20%.

Detailed Forecast

Synopsis

Wet trade wind weather is in store through the week as an upper trough lingers across the state. Trade flow at the surface will provide a steady stream of clouds and showers mainly to windward and mauka areas.

Discussion

A broad surface trough across the western islands appears to be moving westward this morning. Patches of broken to overcast showery low clouds are embedded within moderate to breezy trade flow, which veers slightly and gradually from west to east. Because the troughing is broad, no sharp convective boundaries formed across local waters overnight. Instead, a steady and rather evenly distributed supply of showers was the rule. Radar shows scattered to numerous showers either passing through the channels or affecting mainly windward and mauka areas on the islands. Broken to overcast middle and high clouds, marking the eastern flank of an upper trough, cover skies from Molokai eastward.
East to northeast trade winds will spread westward through today, maintaining the current shower pattern through much of the forecast period. The threat of flash flooding has decreased, so the Flash Flood Watch for Kauai and Niihau has been cancelled. The upper trough straddling the state continues to destabilize our airmass. There is a slight chance of thunderstorm development across leeward Big Island slopes this afternoon. Models show the upper trough will remain through the week. Therefore, we expect a wet trade wind pattern, with rainfall maxima occurring overnight and during the early morning hours.

Aviation

The axis of a surface trough has moved into the Kauai Channel and continues to move steadily west. Areas of MVFR in lower ceilings and showers will be affecting the state through the day, mainly over windward and mauka sections. Winds will be from the east to east-northeast in the moderate to locally breezy range.
AIRMET Sierra remains in effect for mountain obscuration in low clouds and showers for Kauai.
AIRMET Tango remains in effect for low-level turbulence over and downwind of the terrain in Kauai, but will likely be cancelled later this morning as winds ease. However, AIRMET Tango remains posted for high-level turbulence over the entire island chain.

Marine

Weak surface troughing over the western end of the state is providing just enough focus for widely scattered showers and isolated thunderstorm development. This trough will further weaken as it gradually moves west through the morning hours. This will open up a period of more pronounced east trade flow that will persist over the next several days. A developing surface high located far northeast of the chain will strengthen going into the weekend. This will create a tight enough pressure gradient back across the local waters to strengthen weekend trades from fresh magnitudes Thursday and Friday to strong to near gale force over the weekend. Locally strong Small Craft Advisory (SCA) level winds through the notoriously windier channels and bays along with those waters south of the Big Island may commence as early as this afternoon. Thus, while morning seas will fall below the 10 foot SCA criteria with the subsiding north swell, an SCA for winds will remain in effect for the Pailolo Channel, Maalaea Bay, the Alenuihaha Channel and the southern Big Island waters for the foreseeable future.
The most recent XL northwest turning north swell that has been producing large, rough and disorganized surf will gradually diminish through the day. Surf will remain below advisory heights along all shores through Thursday night. A high to near XL, long period northwest swell arrives Friday and Saturday. These swells are forecast to peak surf heights around warning levels along the smaller island northern and western exposed shorelines…near advisory levels along the Big Island’s north and west shores. Strengthened east trades near and upstream of the state will deliver shorter period, choppy wind wave swell through the week along eastern-facing shores. This may generate near 8 foot advisory surf along the state’s eastern exposed coasts this weekend into early next week. Severe gale force winds associated with a Tuesday Tasman Sea storm system will provide the fetch needed to send background southwest swells toward the islands. This may provide a small bump in south-facing shoreline surf to near typical winter time averages early next week.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov