Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 87 near the shore to around 75 above 3000 feet. East winds up to 15 mph shifting to the southeast in the afternoon. Chance of rain 40 percent.

Tonight: Partly cloudy with isolated showers. Lows 68 to 73 near the shore to around 59 above 3000 feet. Northeast winds up to 15 mph. Chance of rain 20 percent.

Friday: Mostly sunny. Isolated showers in the afternoon. Highs around 86 near the shore to around 74 above 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny with isolated showers. Highs around 84. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Isolated showers in the evening, then scattered showers after midnight. Lows 66 to 72. Northeast winds 10 to 15 mph. Chance of rain 40 percent.

Friday: Partly sunny in the morning then becoming mostly sunny. Breezy. Isolated showers. Highs around 83. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Partly sunny with scattered showers. Highs 74 to 81 in the valleys to around 65 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 59 to 64 in the valleys to around 54 above 4000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Friday: Partly sunny with scattered showers. Highs 73 to 80 in the valleys to around 64 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

North Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 77 to 86. Southeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows 62 to 72. Southeast winds up to 15 mph. Chance of rain 40 percent.

Friday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs 76 to 85. East winds up to 15 mph. Chance of rain 40 percent.

East Kaua’i

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 77 to 85. Northeast winds up to 15 mph shifting to the east in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows 60 to 73. Northeast winds around 10 mph. Chance of rain 50 percent.

Friday: Partly sunny with isolated showers in the morning, then mostly sunny with scattered showers in the afternoon. Highs 76 to 84. East winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

A weak cold front passing east of the Hawaii Region will allow the high pressure ridge to build north of the island chain. Trade winds will strengthen into the moderate to locally breezy range today and hold into the weekend. Local scale land and sea breezes will diminish with strengthening trade winds. Any rain shower activity will be brief in this stable environment and favor windward and mountain areas during the overnight to early morning hours. The next chance for enhanced rain showers will occur on Monday as clouds from an old frontal band drift into the islands from the north.

Discussion

The satellite imagery this morning continues to show a fairly stable environment across the region. Cirrus clouds associated with the subtropical jet stream are outlining a stable upper level ridge over the main Hawaiian Islands. Scattered stable cumulus clouds upstream of the state will yield little rainfall as they drift across island mountain ranges through the upcoming weekend. Upper air weather balloon soundings from Lihue and Hilo at 2 AM HST this morning, show temperature inversion base heights at 6,500 and 5,500 feet respectively, which means very stable conditions for all islands.
The weak cold front passing to the east of the Hawaii Region today will allow high pressure will build in, keeping a fairly stable weather pattern in place with a slight increase to easterly trade wind speeds reaching the moderate to locally breezy range through Friday and then holding at these levels through the upcoming weekend. Local scale afternoon sea breezes will diminish as the large scale trade winds strengthen.
A high pressure ridge aloft will keep weather conditions on the stable side through the upcoming weekend. Subsidence temperature inversion heights will remain in the 5,000 to 7,000 foot range through Sunday. These low inversion heights are caused by downward motions under the stable ridge aloft and will limit vertical cloud growth and any rain shower production will be brief.
There is hope for a brief period of increasing shower trends on Monday as both the American (GFS) and European (ECMWF) models suggest a cloud band from an old cold front will drift through the islands starting early Monday morning. Passing showers may develop once again favoring early Monday morning, and Monday night into Tuesday morning. The eastern slopes of the Big Island may see a more sustained period of enhanced rainfall as these clouds are driven up the mountain slopes and produce scattered to numerous showers along the Hilo side from Monday night through Wednesday morning.

Aviation

Moderate to locally breezy trade winds will push clouds and a few showers over the islands through tomorrow with the focus of these showers over windward and mountain areas. Leeward areas could see some additional clouds and showers develop this afternoon.
No AIRMETs are currently in effect.

Marine

A front passing far north of the main Hawaiian Islands will weaken the subtropical ridge to our north, keeping trade wind speeds below advisory strength. Trade winds will increase from tonight onward as the ridge rebounds with the departure of the front. Locally strong winds will likely return for the typical windy areas around Maui County and the Big Island. A Small Craft Advisory is in effect for these waters beginning tonight.
Small surf will continue along south facing shores as a mix of long period south and southwest (170-220 degree) swells continues into next week. Surf along exposed north and west facing shores may increase slightly today as a west-northwest to northwest (300-320 degree) swell fills in from former Typhoon Mawar. Surf along east facing shores will remain small today due to weaker trade winds. A slight increase is expected Friday into the weekend as trade winds strengthen.

HFO Watches/Warnings/Advisories

Small Craft Advisory from 6 PM this evening to 6 AM HST Saturday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov