Photo Credit: Jason Weingardt

West Kaua’i

Today: Breezy. Mostly sunny with scattered showers. Highs around 88 near the shore to around 76 above 3000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Lows 69 to 74 near the shore to around 60 above 3000 feet. East winds up to 15 mph.

Thursday: Mostly sunny. Highs around 89 near the shore to around 77 above 3000 feet. East winds up to 15 mph.

South Kaua’i

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs around 85. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows 67 to 73. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Thursday: Mostly sunny. Breezy. Isolated showers in the morning. Highs around 86. East winds 10 to 20 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Partly sunny. Breezy. Occasional showers in the morning, then scattered showers in the afternoon. Highs 75 to 82 in the valleys to around 66 above 4000 feet. East winds up to 20 mph. Chance of rain 90 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 60 to 65 in the valleys to around 55 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Thursday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 76 to 83 in the valleys to around 67 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

North Kaua’i

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 78 to 87. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 63 to 73. Southeast winds up to 15 mph. Chance of rain 20 percent.

Thursday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 79 to 88. East winds up to 15 mph. Chance of rain 20 percent.

East Kaua’i

Today: Partly sunny with scattered showers. Highs 78 to 86. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 61 to 75. East winds 10 to 15 mph. Chance of rain 20 percent.

Thursday: Partly sunny in the morning then becoming mostly sunny. Isolated showers. Highs 79 to 87. East winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate to locally breezy trades will maintain a relatively dry pattern into early next week. Windy conditions and some wet weather could potentially develop around the middle of next week as tropical cyclone Calvin nears the islands from the east.

Discussion

Currently at the surface, a 1033 mb high is centered around 1550 miles north-northwest of Honolulu, and is driving moderate trade winds in unsheltered areas across the island chain early this morning. Infrared satellite imagery shows partly cloudy conditions across the state, with a bit more cloud cover in some windward areas as well as much of Kauai. Radar imagery shows isolated to scattered showers moving into windward areas, with mainly dry conditions in leeward locales. Main forecast attention is on the potential for a tropical cyclone Calvin or its remnant low to affect the island weather during the middle part of next week.
A ridge of high pressure north of the islands will keep moderate to locally breezy trade winds blowing through Monday. The trades could potentially get really windy next Tuesday as the tropical cyclone Calvin or its remnant low nears the island chain. Rather dry trade wind weather is expected to prevail today through Friday as precipitable water values remain well below normal and inversion heights hover around 5 kft. The airmass is expected to moisten up over the weekend, bringing a return of more typical trade wind weather to the island chain. Subsidence in advance of tropical cyclone Calvin could lower shower coverage on Monday into Tuesday, with some wet weather potentially affecting the state in association with this system around the middle of next week.

Aviation

The high pressure ridge far north of the islands will continue to produce moderate to breezy easterly trade winds through the week, with clouds and showers favoring windward and mauka areas. Expect mainly VFR conditions, with brief periods of MVFR conditions possible in showers.
AIRMET Tango remains in effect for moderate turbulence over and in the lee of island mountains due to breezy trade winds. Conditions will continue through at least tonight.

Marine

Easterly trade winds have surged back overnight, which has led to the Small Craft Advisory being expanded to most waters around Maui County and the Big Island, including Kaiwi Channel. Guidance depicts fresh to strong easterly trades continuing into the weekend. Tropical Storm Calvin in the far eastern Pacific is forecast to enter the Central Pacific basin Sunday night as a Tropical Storm, then move into the far eastern portion of the offshore waters early next week. Although confidence in any details is low being this far out in time, all interests should monitor the latest advisories issued by the National Hurricane Center in Miami, Florida under WMO header WTPZ33 KNHC.
Surf along south facing shores will remain up into Thursday as a south-southwest swell moves through. A return of background level south-southwest and southeast swell energy moving through is anticipated Friday through the weekend.
Surf along east facing shores will remain rough and choppy each day through the weekend. Long-period forerunners from Calvin are forecast to arrive early next week and build up the island chain. This will likely translate to building surf, especially for east facing shores of the eastern end of the state. More details will follow as the week continues and confidence improves.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Thursday for Kaiwi Channel, Maui County Windward Waters, Big Island Windward Waters.
Small Craft Advisory until 6 PM HST Friday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov