Photo Credit: Brendan Stephen

West Kaua’i

Today: Sunny. Isolated showers in the afternoon. Highs 81 to 86 near the shore to around 73 above 3000 feet. Northeast winds up to 15 mph shifting to the southeast in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows 64 to 69 near the shore to around 56 above 3000 feet. Northeast winds up to 15 mph.

Wednesday: Mostly sunny. Highs 81 to 86 near the shore to around 72 above 3000 feet. East winds around 10 mph in the morning becoming light.

South Kaua’i

Today: Mostly sunny. Highs 80 to 86. Northeast winds 10 to 15 mph.

Tonight: Mostly clear. Lows around 66. Northeast winds 10 to 15 mph.

Wednesday: Mostly sunny. Highs 80 to 86. East winds around 10 mph.

Kaua’i Mountains

Today: Sunny in the morning then becoming partly sunny. Isolated light showers. Highs 73 to 79 in the valleys to around 65 above 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 58 to 64 in the valleys to around 54 above 4000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Wednesday: Mostly sunny. Isolated showers in the morning. Highs 73 to 79 in the valleys to around 64 above 4000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

North Kaua’i

Today: Sunny. Isolated showers in the afternoon. Highs 75 to 83. Southeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Lows 59 to 68. Southeast winds up to 15 mph.

Wednesday: Mostly sunny. Highs 74 to 83. East winds around 10 mph.

East Kaua’i

Today: Sunny. Isolated showers in the afternoon. Highs 73 to 83. Northeast winds up to 10 mph shifting to the east in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows 59 to 70. Northeast winds 10 to 15 mph.

Wednesday: Mostly sunny. Highs 72 to 83. East winds around 10 mph.

Detailed Forecast

Synopsis

Dry and stable conditions will limit shower chances across the islands through the upcoming weekend. Light to moderate trade winds will focus a few showers along windward areas at times this week.

Discussion

Only minor changes to the forecast package this morning. Lowered the low temperature forecast just a little, at times this week, to account for continued drying of low level moisture. Dew pts are forecast to fall into the lower and mid 60s.
Surface and upper level ridging centered over the region, will continue to generate dry and stable conditions across the islands this week. The dry and stable airmass which has already limited showers since Sunday (when moisture depths were 6-7k ft), will become even more stable this week (moisture depths 4-6k ft) in response to the deep layer subsidence anchored over the region. Light to moderate trade winds will focus clouds and a few isolated showers over windward and mauka areas this week.
A cold front will approach the area from the northwest Thursday and disrupt the trade wind flow briefly across the islands. The front will weaken and quickly exit northeast, allowing trade wind flow to develop across much of the state Friday. Light background winds Thursday will allow for a period of land sea breeze circulations, however the dry airmass will limit the potential for any afternoon sea breeze showers across leeward areas.
The weekend into early next week…the airmass remains stable and mainly dry through the period. However forecast moisture depths will increase some early next week, in advance of another front approaching Kauai from the northwest. This pattern may help increase the chance for showers by next Tuesday.

Aviation

Light to moderate easterly trades will prevail through late morning. By early afternoon, sea breeze development may affect areas along the immediate leeward coasts and help generate isolated showers over interior areas and higher elevations. Elsewhere, expect VFR conditions and partly cloudy skies.
No AIRMETs are currently in effect.

Marine

High pressure ridging at all levels is currently anchored across the region. Easterly trade winds have strengthened over the nearshore waters as a surface ridge just north of 24N continues to drift northward early this morning. Surface high pressure will center itself northeast of the state through the middle of the week. This will tighten the local pressure gradient up just enough across the islands to produce moderate to fresh east trades. Early morning ASCAT passes have shown evidence of fresh to strong trades channeling through the notoriously windier areas surrounding Maui County and Big Island. Thus, a Small Craft Advisory is in effect for these waters through early Wednesday morning. A couple of approaching fronts from the northwest will weaken the western edge of the ridge from late Wednesday through New Year's Day. These nearing fronts will veer light winds more southeasterly late this week. After a day of generally moderate east to southeast winds Wednesday, light southeast to (more western island) variable breezes will occur across many Hawaiian coastal zones Thursday. A front will wash out north of the state Friday with high pressure passing off to the north that will result in a brief shot of strengthened east trades that day. A surface ridge trailing the high will be pushed toward the islands this weekend and cause east southeast winds to ease going into the new year.
A series of northwest to west northwest swells will pass through the next several days. The most recent west northwest (310-320 degree) swell that peaked this past holiday weekend surf will be leveling off through the day. The next moderate size, medium period west to northwest (310 degree) swell on its heels will build in beginning Wednesday and potentially lift north and west-facing shore surf back up to High Surf Advisory (HSA) levels Thursday and Friday. A slightly larger northwest swell arriving around New Year's Day (Sunday) may also generate a HSA event Monday. East- facing shore wind wave chop will remain small this week. A short term boost in easterlies the next couple of days will likely add another foot or two onto east faces.

HFO Watches/Warnings/Advisories

Wind Advisory until 6 PM HST this evening for Big Island Summits.
Small Craft Advisory until 6 AM HST Wednesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov