Hilo

Today: Scattered showers. Partly sunny, with a high near 84. Light and variable wind becoming east northeast 5 to 9 mph in the morning. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Occasional showers. Low around 65. Northeast wind 5 to 8 mph becoming light and variable after midnight. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Showers likely, mainly before noon. Partly sunny, with a high near 84. Calm wind becoming east northeast 5 to 9 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Isolated showers after 1pm. Mostly sunny, with a high near 80. Light and variable wind becoming west 5 to 7 mph in the afternoon. Chance of precipitation is 20%.

Tonight: Scattered showers, mainly between 7pm and 1am. Partly cloudy, with a low around 64. West wind 6 to 8 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Isolated showers before 7am, then scattered showers after 1pm. Mostly sunny, with a high near 80. Northwest wind around 7 mph becoming south southeast in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Waimea

Today: Scattered showers. Partly sunny, with a high near 79. Breezy, with a northeast wind 18 to 20 mph, with gusts as high as 28 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 57. Breezy, with a northeast wind 15 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 50%. New precipitation amounts between a tenth and quarter of an inch possible.

Wednesday: Scattered showers. Partly sunny, with a high near 79. Breezy, with a northeast wind 8 to 18 mph, with gusts as high as 26 mph. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

Kohala

Today: Scattered showers. Partly sunny, with a high near 65. Breezy, with an east wind 10 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Occasional showers. Low around 52. Breezy, with an east wind 10 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday: Showers likely, mainly before noon. Partly sunny, with a high near 65. East wind 9 to 14 mph, with gusts as high as 20 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Mostly sunny, with a high near 85. Windy, with an east wind 21 to 26 mph, with gusts as high as 34 mph.

Tonight: Isolated showers. Partly cloudy, with a low around 73. Windy, with an east wind 20 to 23 mph, with gusts as high as 30 mph. Chance of precipitation is 20%.

Wednesday: Isolated showers. Mostly sunny, with a high near 85. Windy, with an east wind 18 to 23 mph, with gusts as high as 29 mph. Chance of precipitation is 20%.

Puna

Today: Showers likely, mainly before noon. Partly sunny, with a high near 83. Northeast wind 9 to 11 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Occasional showers. Low around 63. Northeast wind 7 to 11 mph becoming northwest after midnight. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

Wednesday: Showers likely, mainly before noon. Partly sunny, with a high near 83. Northwest wind 7 to 14 mph becoming northeast in the afternoon. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

Waikoloa

Today: Isolated showers after noon. Mostly sunny, with a high near 85. Breezy, with a northeast wind 16 to 22 mph, with gusts as high as 32 mph. Chance of precipitation is 20%.

Tonight: Isolated showers before midnight. Partly cloudy, with a low around 65. Breezy, with a northeast wind 13 to 18 mph, with gusts as high as 26 mph. Chance of precipitation is 20%.

Wednesday: Isolated showers after noon. Mostly sunny, with a high near 85. Breezy, with an east northeast wind 11 to 16 mph becoming light and variable in the afternoon. Winds could gust as high as 23 mph. Chance of precipitation is 20%.

Detailed Forecast

Synopsis

Breezy trade winds will prevail today, then trend down into the light to moderate range for the tail end of the work week. The trades will ramp back up over the weekend, reaching breezy levels once again Sunday through early next week. Showers will favor windward and mauka areas through the period, with a stray shower reaching leeward areas from time to time.

Discussion

Currently at the surface, a 1035 mb high is centered around 1450 miles north-northwest of Honolulu, and is driving moderate to breezy trade winds across the island chain early this morning. Infrared satellite imagery shows mostly cloudy skies in most windward areas, with partly cloudy conditions in most leeward locales. Radar imagery shows scattered showers moving into windward areas, with a stray shower spilling leeward from time to time. Main short term concerns revolve around rain chances and trade wind trends during the next couple days.
High pressure will remain nearly stationary to the north- northwest of the islands today, keeping moderate to breezy trade winds in place. The high will merge with a new stronger high to the distant northwest tonight through the end of the work week, while a weak surface trough gradually amplifies as it slides by to the north of the state. This will diminish the trades down into the light to moderate range for the tail end of the work week, and allow for localized sea and land breeze development in the more sheltered leeward areas. As the surface trough shifts northwestward and a new strong high builds north of the islands over the weekend, the trades will ramp back up, reaching breezy levels Sunday through early next week.
As for the remaining weather details, a fairly typical trade wind shower pattern will hold in place through Wednesday night. Showers will favor windward and mauka areas, particularly at night and during the early morning hours, with a stray shower reaching leeward areas from time to time. Scattered trade wind showers will continue to affect windward areas Thursday through Saturday, with a few leeward showers possible during the afternoon hours as localized sea breezes develop. A more typical trade wind shower pattern appears to resume Sunday through early next week, with showers favoring windward and mauka areas and the occasional shower spilling over into leeward communities.

Aviation

Moderate easterly breezes will persist this morning and bring scattered showers mainly to windward areas. Expect periods of MVFR ceilings and visibility with this activity. Otherwise, isolated showers may intermittently pass over the terrain and affect the leeward side of the islands.
AIRMET Tango remains in effect below 8000 feet over and immediately south thru west of mountains of all islands due to tempo moderate turbulence.
AIRMET Sierra remains in effect for northeast through southeast sections of the Big Island from Upolu Point to Cape Kumukahi to Apua Point above 2500 feet due to mountain obscuration from low clouds and showers.

Marine

A surface ridge located far north of the islands is maintaining locally strong trade winds across the state early this morning. As a result, a Small Craft Advisory (SCA) remains in effect for the typically windier waters adjacent to the islands of Maui County and the Big Island through early Wednesday morning. The trade winds are forecast to weaken slightly from Wednesday through Friday. For the upcoming weekend, recent model guidance suggests a new surface ridge will build far north of the islands. Therefore, the latest forecast suggests that SCA conditions may redevelop over the typically windier waters as early as Saturday.
A large, long-period south-southwest swell continues to spread up over the Hawaiian Waters early this morning. Recent observations from the nearshore buoys just south of the islands indicate the swell height is 4 to 5 feet with a wave period of approximately 17 seconds. Surf along south facing shores will remain elevated due to this swell. Therefore, a High Surf Advisory is in effect for the south facing shores of all Hawaiian Islands through Wednesday afternoon. This south-southwest swell will gradually lower from Wednesday night through Friday. By this weekend, expect much smaller surf along south facing shores due to various small background south swells.
The locally strong trades will produce moderate, choppy surf along east facing shores today. A downward trend is expected in surf heights along east facing shores from late tonight and Wednesday through the second half of this week due to the weakening of the trades in the vicinity of, as well as upstream of, the islands.
Surf along north facing shores will remain just above typical summertime flat conditions today due to a small northwest swell. A return to nearly flat conditions is expected during the second half of this week along north facing shores.

HFO Watches/Warnings/Advisories

High Surf Advisory until 6 PM HST Wednesday for Niihau, Kauai Leeward, Waianae Coast, Kahoolawe, Maui Leeward West, Kona, Kauai South, East Honolulu, Honolulu Metro, Ewa Plain, Molokai Southeast, Molokai Leeward South, Lanai Leeward, Lanai South, Maui Central Valley South, Kipahulu, South Maui/Upcountry, South Haleakala, Big Island South, Big Island Southeast.
Small Craft Advisory until 6 AM HST Wednesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov