Photo Credit: Tyler Rooke

West Side

Today: Isolated showers. Mostly sunny, with a high near 83. Light and variable wind. Chance of precipitation is 20%.

Tonight: Isolated showers. Partly cloudy, with a low around 67. Light and variable wind. Chance of precipitation is 20%.

Thursday: Scattered showers. Partly sunny, with a high near 83. East northeast wind around 8 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

South Side

Today: Isolated showers after 1pm. Mostly sunny, with a high near 83. Light and variable wind becoming west around 5 mph in the afternoon. Chance of precipitation is 20%.

Tonight: Isolated showers before 1am. Partly cloudy, with a low around 65. West wind around 5 mph becoming light and variable after midnight. Chance of precipitation is 20%.

Thursday: Scattered showers after 7am. Partly sunny, with a high near 83. Light north wind becoming northeast 6 to 11 mph in the morning. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

North Shore

Today: Scattered showers. Partly sunny, with a high near 81. East wind 11 to 14 mph, with gusts as high as 18 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 66. East wind around 11 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Thursday: Scattered showers. Mostly cloudy, with a high near 81. East northeast wind around 14 mph, with gusts as high as 18 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Central Maui

Today: Scattered showers. Partly sunny, with a high near 81. Northeast wind 7 to 9 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 64. Northeast wind around 7 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Thursday: Scattered showers. Mostly cloudy, with a high near 81. Northeast wind around 11 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Upcountry

Today: Isolated showers after noon. Mostly sunny, with a high near 68. Light and variable wind. Chance of precipitation is 20%.

Tonight: Isolated showers before midnight. Mostly cloudy, with a low around 54. Northwest wind around 6 mph becoming light and variable after midnight. Chance of precipitation is 20%.

Thursday: Showers likely, mainly after noon. Mostly cloudy, with a high near 68. East wind 9 to 13 mph. Chance of precipitation is 60%. New precipitation amounts between three quarters and one inch possible.

East Maui

Today: Scattered showers. Partly sunny, with a high near 79. Southeast wind 5 to 8 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely. Mostly cloudy, with a low around 62. East wind around 10 mph. Chance of precipitation is 70%. New precipitation amounts between a quarter and half of an inch possible.

Thursday: Showers likely. Mostly cloudy, with a high near 79. East wind around 11 mph. Chance of precipitation is 70%. New precipitation amounts between a quarter and half of an inch possible.

Lanai City

Today: Scattered showers, mainly after noon. Mostly sunny, with a high near 73. Northeast wind 5 to 9 mph becoming light in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers after midnight. Mostly cloudy, with a low around 65. North northeast wind 3 to 6 mph. Chance of precipitation is 30%. New precipitation amounts between a tenth and quarter of an inch possible.

Thursday: Scattered showers. Partly sunny, with a high near 75. East northeast wind 7 to 10 mph. Chance of precipitation is 40%. New precipitation amounts between a half and three quarters of an inch possible.

Kaunakakai

Today: Isolated showers. Mostly sunny, with a high near 80. East wind 7 to 11 mph. Chance of precipitation is 20%.

Tonight: Isolated showers. Partly cloudy, with a low around 70. East northeast wind 5 to 8 mph. Chance of precipitation is 20%.

Thursday: Scattered showers. Partly sunny, with a high near 80. Breezy, with an east wind 13 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Detailed Forecast

Synopsis

A front just northwest of Kauai this morning will continue to bring heavy rain and thunderstorms to Kauai for the next few days. Wet trade wind weather is expected for the rest of the state into the weekend.

Discussion

Little change in the forecast with the morning package. Did boost the PoPs and associated fields have been adjusted over the western half of Kauai this morning to better reflect the trends on radar overnight.
The front is just northwest of Kauai early this morning, but plenty of showers and thunderstorms have been noted ahead of the front overnight. For the first half of the night, most of the rain stayed just off shore, but within the last couple of hours, rain has moved onshore, and we are seeing rises on a number of streams, mainly along the northern half of the island.
An upper level trough associated with the front is helping upper level temperatures to fall below normal, indicating an unstable atmosphere. The Lihue sounding reported -12.5 C for a 500 mb temperature overnight, while Hilo had -11.1 C. Precipitable water (PW) at Lihue was 1.53 inches, which is above normal, while Hilo had a slightly drier airmass overhead with 1.15 inches, which is near normal. The most unstable air is expected to remain over Kauai through tomorrow as the models continue to show the front stalling overhead, before beginning to weaken. Expect the front to pushing over Kauai later today and then stall. As such, thunderstorms and heavy rain remain only over Kauai and the adjacent waters. A Flash Flood Watch continues for Kauai County through Thursday as a result.
While the front gets caught up over Kauai, the rest of the state is expected to continue with easterly winds, which will focus shower activity over the windward slopes. Wetter than normal precipitable water along and ahead of the front is expected to reach over the central islands. Meanwhile, the colder temperatures aloft could spark some afternoon thunderstorms over the Big Island slopes during the next couple of afternoons. Wet conditions looks to remain into the weekend before tapering off Sunday into next week.

Aviation

The aviation hazard of note in the near term is the vigorous convective response and widespread lightning over much of Kauai. These thunderstorms developed as breezy northerly winds reached the north-facing slopes of the island during the last 90 minutes or so, and they will continue to evolve southward toward PHLI. Thunderstorms will remain possible over and around Kauai through most or all of the forecast period as the front exhibits little movement.
Prevailing VFR will continue for Oahu through Big Island today while moderate easterlies tend to focus showers over windward and mauka sections. In addition, improved moisture quality will again lead to thunderstorm potential over Big Island during peak heating, particularly the leeward side.
AIRMET Sierra for mountain obscuration remains in effect for Kauai.

Marine

A front just west and northwest of the area has been nearing Kauai, where it will stall and dissipate over the next couple of days. Light east to southeast flow will prevail ahead of the front through today, with breezy to locally strong northeast winds filling in behind the front. (Winds and seas may reach Small Craft Advisory (SCA) levels in the areas with the stronger winds.) Strengthening high pressure will be passing by north of the area later in the week and on through the weekend. Winds and seas are expected to reach SCA levels across more areas by Thursday night or Friday, with these conditions continuing through the weekend.
The current medium period northwest swell will get reinforced by a new swell today. This swell will linger but lower gradually through Friday. A small, but long-period, northwest swell is expected to fill in Friday night and Saturday, with a slightly larger northwest swell expected Monday and Tuesday. Surf heights are forecast to remain below High Surf Advisory (HSA) levels.
With the expected strengthening of the trade winds over the weekend, short-period choppy surf will gradually increase over that time frame and into early next week. Surf heights may eventually approach HSA levels. Small, mainly background southerly swells will continue throughout the forecast period.

HFO Watches/Warnings/Advisories

Flash Flood Watch through Thursday afternoon for Niihau, Kauai.

Data Courtesy of NOAA.gov