Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly cloudy. Scattered showers in the morning, then numerous showers in the afternoon. Highs around 82 near the shore to around 70 above 3000 feet. Southwest winds 10 to 15 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows around 67 near the shore to around 57 above 3000 feet. Southwest winds around 10 mph. Chance of rain 70 percent.

Wednesday: Mostly cloudy with scattered showers. Highs around 81 near the shore to around 69 above 3000 feet. Southwest winds 10 to 15 mph. Chance of rain 50 percent.

South Kaua’i

Today: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 81. Southwest winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows around 67. Southwest winds 10 to 15 mph. Chance of rain 70 percent.

Wednesday: Mostly cloudy with scattered showers. Highs around 80. Southwest winds 10 to 15 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Mostly cloudy. Breezy. Scattered showers in the morning, then numerous showers in the afternoon. Highs 72 to 79 in the valleys to around 64 above 4000 feet. Southwest winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with numerous showers. Lows around 61 in the valleys to around 53 above 4000 feet. Southwest winds 10 to 15 mph. Chance of rain 70 percent.

Wednesday: Partly sunny with scattered showers in the morning, then cloudy with numerous showers in the afternoon. Highs 70 to 77 in the valleys to around 63 above 4000 feet. Southwest winds 10 to 15 mph. Chance of rain 70 percent.

North Kaua’i

Today: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 74 to 82. Southwest winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 60 to 69. Southwest winds 10 to 15 mph. Chance of rain 50 percent.

Wednesday: Mostly cloudy with scattered showers. Highs 73 to 80. Southwest winds 10 to 15 mph. Chance of rain 50 percent.

East Kaua’i

Today: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 75 to 83. Southwest winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers. Lows 59 to 70. Southwest winds around 10 mph. Chance of rain 50 percent.

Wednesday: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 72 to 81. Southwest winds 10 to 15 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Kauai and Oahu can expect a boost in showers today and Wednesday as a front passes just north of the islands. Otherwise, light to moderate southerly winds will focus showers over the leeward areas of Kauai and Oahu through the week, while mostly dry conditions continue for Maui County and the Big Island. A developing upper- level trough west of the islands this weekend could send another front with enhanced showers towards portions of the state early next week.

Discussion

As expected, no major changes to the forecast with the morning package. The winds at the summits of the Big Island have continued to trend downwards through the night, and have fallen below advisory criteria. As such, the Wind Advisory for the Big Island Summits has been cancelled. In general, the forecast has been tweaked towards the latest data from the National Blend of Models (NBM). The NBM solution is not as aggressive as some of the other models, and seems to be more in line with what we are seeing on satellite and radar at this time.
An upper level zonal flow remains north of the islands, and this is helping to usher low pressure systems and their fronts from west to east. The zonal flow will help keep these systems north of the islands, however the front will brush the northern islands, resulting in an uptick in showers over Kauai and to a lesser extent Oahu through tomorrow. During this time, and persisting into the weekend, southerly winds will remain over the region. During the second half of the week the southerly winds will help to focus limited shower activity over the leeward areas of Kauai and Oahu. Throughout the week there remains a chance for some briefly heavier showers over the Big Island slopes during the afternoon hours with the lighter winds.
Satellite shows layered clouds north of the main Hawaiian Islands, with some high clouds streaming over Kauai and Oahu this morning. Expect some of the lower clouds with showers to move over Kauai later this morning and lingering into tomorrow. At times some of these clouds and showers could reach Oahu. That being said, the front associated with these clouds is expected to remain just north of the islands.
Heading into Saturday, the global models show changes in the upper levels as an upper level trough digs southward to the northwest of islands. An associated surface low passes north of the islands, but the upper level trough would help to drive an associated cold front towards the islands early next week. The ECMWF and GFS both develop an upper level low along the trough, with the ECMWF being more aggressive than the GFS. Will continue to monitor the development of this situation over the coming days.

Aviation

A surface low pressure system located north-northwest of Kauai will continue to move toward the east-northeast today. In addition, a weak surface ridge will remain in the vicinity of the southern Big Island. The close proximity of these features to the state is maintaining light to locally moderate south to southwest background winds across most of the island chain.
Convergence bands and topographic lift associated with the south to southwest flow are expected to cause low clouds and showers to increase in coverage over the western islands this morning. Therefore, expect brief periods of MVFR conditions to occur as these clouds and showers move over parts of Kauai and Oahu. MVFR ceilings may also continue over portions of Molokai and Lanai this morning. Otherwise, VFR conditions will likely prevail over most areas.
No AIRMETs are currently in effect. AIRMET Sierra may be needed for mountain obscuration on Kauai or Oahu later today if the low clouds and showers become widespread.

Marine

Ridge will meander over and south of the islands through the rest of the week as a series of lows move through from west to east along a frontal boundary positioned nearby to the north. This pattern supports periods of gentle to moderate south to southwest winds. Expect the strongest of these winds and choppier seas over the Kauai and Oahu waters, closer to the lows passing through to the north. The eastern end of the state will remain near the ridge axis, which will translate to land and sea breeze conditions near the coasts with a background southerly flow prevailing.
Seas will remain on the small side this week for all Hawaiian waters with minimal swell energy expected. This quiet period will persist until the blocking pattern that has setup over the far northwest Pacific shunting the jet stream northward breaks down. Long-range guidance does, however, depict a short- to medium- period north swell arriving early next week, which could drive the seas up toward the 10 ft advisory level if it materializes.
Limited swell translates to small surf prevailing for all shores this week with mainly a mix of background north and south swell energy moving through. For the long range, decent sized area of strong southerly breezes setting up within our swell window southeast of New Zealand overnight is forecast to nose northward keeping the winds focused as the islands down the 190 degree directional band over the next day or two. This pulse should reach Pago Pago this weekend according to WW3, then our southern shores next week from Tuesday through midweek.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov