Photo Credit: James Grenz

Hilo

Today: Scattered showers, mainly before 1pm. Partly sunny, with a high near 84. Light and variable wind becoming east 5 to 9 mph in the afternoon. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers, mainly after 7pm. Mostly cloudy, with a low around 63. East wind 5 to 8 mph becoming light and variable. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Scattered showers. Partly sunny, with a high near 83. Light and variable wind becoming east southeast 5 to 8 mph in the afternoon. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Isolated showers after noon. Partly sunny, with a high near 79. Light and variable wind becoming west northwest 5 to 9 mph in the morning. Chance of precipitation is 20%.

Tonight: Isolated showers. Partly cloudy, with a low around 62. West northwest wind 5 to 7 mph becoming calm. Chance of precipitation is 20%.

Wednesday: Isolated showers after noon. Partly sunny, with a high near 79. West wind 5 to 7 mph becoming calm in the afternoon. Chance of precipitation is 20%.

Waimea

Today: Isolated showers. Partly sunny, with a high near 78. Breezy, with a northeast wind 14 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 20%.

Tonight: Scattered showers, mainly after midnight. Mostly cloudy, with a low around 55. Breezy, with a northeast wind 11 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Scattered showers. Partly sunny, with a high near 78. Breezy, with a northeast wind 10 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Kohala

Today: Isolated showers. Partly sunny, with a high near 64. Windy, with an east wind 20 to 23 mph, with gusts as high as 32 mph. Chance of precipitation is 20%.

Tonight: Scattered showers, mainly after midnight. Partly cloudy, with a low around 50. Windy, with an east wind 20 to 25 mph decreasing to 13 to 18 mph after midnight. Winds could gust as high as 36 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Scattered showers. Partly sunny, with a high near 64. East wind 7 to 13 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Mostly sunny, with a high near 84. Windy, with an east wind 21 to 25 mph, with gusts as high as 32 mph.

Tonight: Partly cloudy, with a low around 71. Windy, with an east wind 22 to 24 mph, with gusts as high as 31 mph.

Wednesday: Isolated showers after noon. Mostly sunny, with a high near 84. Windy, with an east wind 20 to 24 mph, with gusts as high as 31 mph. Chance of precipitation is 20%.

Puna

Today: Scattered showers. Partly sunny, with a high near 83. Northwest wind 7 to 11 mph becoming east northeast in the afternoon. 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 61. East northeast wind 5 to 9 mph becoming light and variable. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Showers likely, mainly after noon. Partly sunny, with a high near 82. Light and variable wind becoming east 6 to 11 mph in the afternoon. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

Waikoloa

Today: Mostly sunny, with a high near 84. East northeast wind 5 to 11 mph becoming west northwest in the afternoon.

Tonight: Isolated showers before midnight. Partly cloudy, with a low around 63. West northwest wind 5 to 11 mph becoming east northeast after midnight. Chance of precipitation is 20%.

Wednesday: Isolated showers after noon. Mostly sunny, with a high near 84. East northeast wind 6 to 11 mph becoming light and variable in the afternoon. Chance of precipitation is 20%.

Detailed Forecast

Synopsis

High pressure north of the state will keep moderate to locally breezy trades in place through Friday, with the trades easing into the light to moderate range Saturday through Monday as a front approaches and stalls well northwest of the islands. The remnants of an old front will bring an increase in shower coverage and intensity to Kauai and Oahu later this morning through Wednesday, with rain chances expected to be the highest over windward areas, particularly on Kauai. A more typical trade wind pattern will return Wednesday night and hold through early next week, with showers favoring windward and mauka areas and a few showers reaching leeward communities from time to time.

Discussion

Currently at the surface, a 1027 mb high is centered around 950 miles north-northeast of Honolulu, and is driving moderate trade winds across the island chain early this morning. Infrared satellite imagery shows quite a bit of high cloud moving overhead, while the leading edge of a roughly 100 mile wide cloud band (the remnants of an old front) are evident around 50 miles north of Kauai and Oahu. Radar imagery shows scattered showers moving into windward sections of Kauai and over the coastal waters to the east and northeast of Oahu. Very little shower activity is noted elsewhere at the moment. Main short term concern revolves around rain chances associated with the old frontal remnants moving through during the next couple days.
High pressure will build eastward well to the north of the islands during the next few days, while a weak disturbance slides westward well to the south of the state. This will keep moderate to locally breezy trades in place through Friday. A front is expected to approach from the northwest Friday night and Saturday, then stall out several hundred miles northwest of the islands Sunday through early next week. As a result, we should see the trades ease into the light to moderate range Friday night and Saturday, and hold at similar levels Sunday into early next week.
As for the remaining weather details, the old frontal remnants are expected to bring an increase in showers particularly to windward sections of Kauai and Oahu beginning later this morning, with fairly wet trade wind weather then holding through Wednesday, particularly for Kauai. Showers will favor windward and mauka areas, but a few showers will also reach leeward communities. Drier trade wind weather will prevail over Maui County and the Big Island, with mainly windward showers.
A disturbance aloft will move southward over or just north of the state Wednesday night and Thursday, then meander in the vicinity of the islands through early next week. Overall, this should bring an increase in trade wind shower coverage and intensity Thursday through early next week. Showers will continue to favor windward and mauka areas, but the elevated inversions will likely send a few more showers into leeward areas as well. Additionally, a thunderstorm or two could develop over the Big Island Thursday afternoon.

Aviation

High pressure north of the state will continue to bring moderate east northeast trades across the islands for the remainder of the day. Isolated to scattered showers will be mainly limited to windward locations with brief periods of MVFR ceilings and visibility possible. Expect VFR conditions and partly cloudy skies elsewhere.
Enhanced low level moisture approaching from the north will bring increased cloud cover and a chance of showers for Kauai and Oahu by this afternoon.
No AIRMETS are currently in effect.

Marine

High pressure north of the islands will maintain moderate to fresh trade winds through the week. Showers will increase over the northern waters today and tonight. Winds will reach Small Craft Advisory thresholds today around the windier waters near Maui and the Big Island. Trade winds may decrease over the weekend as a front develops well northwest of the state.
Surf along south facing shores will remain small through Wednesday, then slowly rise, approaching High Surf Advisory levels over the weekend. A short-period north swell will produce small surf along north facing shores today and diminish tonight and Wednesday. Surf along north facing shores will be minimal through the rest of the week, but a small northwest swell is possible early next week. Trade winds upstream of the islands will produce only small and choppy surf along east facing shores.

HFO Watches/Warnings/Advisories

Small Craft Advisory from noon today to 6 PM HST Wednesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov