Photo Credit: Pamela Goguen Lynch

West Side

Today: Sunny, with a high near 85. East northeast wind around 8 mph.

Tonight: Mostly clear, with a low around 69. East northeast wind around 11 mph.

Thursday: Isolated showers after noon. Mostly sunny, with a high near 85. East northeast wind 5 to 8 mph becoming southwest in the afternoon. Chance of precipitation is 20%.

South Side

Today: Isolated showers after 2pm. Mostly sunny, with a high near 82. East southeast wind around 7 mph. Chance of precipitation is 20%.

Tonight: Isolated showers before 9pm. Mostly clear, with a low around 64. East northeast wind 5 to 7 mph. Chance of precipitation is 20%.

Thursday: Isolated showers after noon. Sunny, with a high near 82. East northeast wind 5 to 8 mph becoming light and variable in the afternoon. Chance of precipitation is 20%.

North Shore

Today: Isolated showers. Mostly sunny, with a high near 83. Breezy, with an east wind 14 to 16 mph, with gusts as high as 22 mph. Chance of precipitation is 20%.

Tonight: Isolated showers. Partly cloudy, with a low around 66. East wind around 14 mph, with gusts as high as 18 mph. Chance of precipitation is 20%.

Thursday: Isolated showers. Mostly sunny, with a high near 83. Breezy, with a northeast wind 15 to 21 mph, with gusts as high as 30 mph. Chance of precipitation is 20%.

Central Maui

Today: Isolated showers. Mostly sunny, with a high near 84. East northeast wind 10 to 13 mph. Chance of precipitation is 20%.

Tonight: Scattered showers, mainly after 9pm. Partly cloudy, with a low around 66. East northeast wind around 11 mph. Chance of precipitation is 30%.

Thursday: Scattered showers. Partly sunny, with a high near 84. Breezy, with a northeast wind 18 to 20 mph, with gusts as high as 28 mph. Chance of precipitation is 30%.

Upcountry

Today: Sunny, with a high near 70. East wind 9 to 13 mph.

Tonight: Mostly clear, with a low around 53. East wind 9 to 13 mph.

Thursday: Isolated showers after 1pm. Sunny, with a high near 70. East wind 5 to 13 mph becoming west in the afternoon. Chance of precipitation is 20%.

East Maui

Today: Scattered showers. Partly sunny, with a high near 78. East southeast wind around 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 69. East northeast wind around 8 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Thursday: Scattered showers. Partly sunny, with a high near 78. East southeast wind 10 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.

Lanai City

Today: Sunny, with a high near 75. Breezy, with an east northeast wind 10 to 15 mph, with gusts as high as 21 mph.

Tonight: Mostly clear, with a low around 61. Breezy, with an east northeast wind 11 to 16 mph, with gusts as high as 22 mph.

Thursday: Isolated showers after noon. Mostly sunny, with a high near 75. East northeast wind 5 to 9 mph becoming light and variable in the afternoon. Chance of precipitation is 20%.

Kaunakakai

Today: Isolated showers between 9am and 2pm. Mostly sunny, with a high near 85. Breezy, with an east northeast wind 16 to 18 mph, with gusts as high as 26 mph. Chance of precipitation is 20%.

Tonight: Mostly clear, with a low around 70. Breezy, with an east northeast wind around 18 mph, with gusts as high as 25 mph.

Thursday: Isolated showers after noon. Sunny, with a high near 85. Breezy, with an east wind 10 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 20%.

Detailed Forecast

Synopsis

Trade winds will continue into the weekend except for a brief respite on Friday with light winds. This short break is due to a front nearing Kauai from the northwest, which falls apart north of Kauai and Oahu Friday night and Saturday. Trade winds will be locally strong today through Thursday, and showers the trade winds bring in will favor the windward and mountain areas, with a few showers drifting leeward of the smaller islands.

Discussion

A new surface high is in the process of taking over as the dominant source for the trade winds. Noted on satellite imagery is a slight hint of a low level trough over Maui County as the northeast winds merges with the easterly trades. Clouds and showers increased considerably in the past few hours just about everywhere. Models dry things up across the island chain this afternoon, supported by an upper level ridge. Not so sure this will happen since there is quite a bit of cloudiness on satellite imagery to be rid off. A wet morning up ahead for most islands, especially the windward and mountain areas. The Puna and Hilo districts looks showery as well that will likely last into the afternoon hours.
The forecast is on track for the moderate to locally strong trade winds turning light Thursday night. A light northwest flow takes over on Friday while a front starts to fall apart while approaching Kauai. The light northwest winds and a stable air mass will allow for only limited afternoon clouds and showers. On Saturday, the trade winds will be filling across the area. But with the upper level disturbance working down the island chain from the northwest, the disturbance may enhance the moisture not only from the front but moisture already in the area. Saturday and Saturday night could be a little showery with brief heavier showers. Won’t rule out an isolated thunderstorm for the higher elevations of the Big Island Saturday, but will hold off on this for now. Sunday appears much drier with mainly moderate trades.

Aviation

Low clouds and showers have expanded in coverage from Molokai through Kauai early this morning. Observations within this corridor still indicate prevailing VFR with brief periods of MVFR possible, particularly over Windward Kauai. Mid-level ridging building across the area from the west combined with diurnal trends will then cause a reduction in shower activity by mid to late morning. Moderate trades will become locally strong this morning into tonight. This will likely prompt issuance of AIRMET Tango for Molokai through Big Island this morning with potential expansion to remaining areas later today.
No AIRMETs are in effect.

Marine

A series of powerful low pressure systems passing well N of the islands will generate NW swells that will propagate through island waters through the next week, with a High Surf Advisory (HSA) posted for exposed N and W facing shores. Generally speaking, peak open ocean swell heights in island waters will be between 10 and 12 feet, resulting in solid advisory-level surf. There remains the potential that these swells will be larger than forecast, which could push surf heights close to warning levels, possibly as early as Thursday.
The fast forward motion of the source lows complicates the surf forecast with respect to both the timing and size, but a peak in surf heights is currently expected tonight and Thursday as a new swell train arrives over the next 12-24 hours. Other peaks are tentatively anticipated on Saturday (with a more northerly component to the swell) and again on Monday/Tuesday. Fine tuning of the short-term surf and sea forecast will be required, driven strongly by observations from offshore NDBC buoys and nearshore PacIOOS buoys. No other significant swells are expected, with relatively small short-period E shore surf diminishing over the weekend.
A Small Craft Advisory (SCA) was scheduled to begin for most waters this morning as the aforementioned rising NW swell combines with shorter-period wind waves to drive an increase in combined seas. However, the swell has been slow to build, and the onset time of the SCA has been pushed back to this evening. A fast- moving high passing N of the area will support a short-term increase in trade winds that will last into Thursday, and a SCA is posted for the windier zones around Maui and the Big Island. Winds will weaken and veer to the SE late Thursday as an approaching front pushes the surface ridge southward over the islands. A new high building NW of the area may push moisture associated with the dissipating front over the area late Friday and Saturday, while also supporting a period of light N to NE winds. A return to moderate E trade wind flow is anticipated by Sunday.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST Thursday for Niihau, Kauai Windward, Kauai Leeward, Waianae Coast, Oahu North Shore, Oahu Koolau, Molokai, Maui Windward West, Maui Central Valley, Windward Haleakala.
Small Craft Advisory until 6 PM HST Thursday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory from 6 PM this evening to 6 PM HST Thursday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Kaiwi Channel, Maui County Windward Waters, Big Island Windward Waters.

Data Courtesy of NOAA.gov