Hilo

Today: Showers likely, mainly before noon. Mostly cloudy, with a high near 74. West wind 5 to 9 mph becoming north in the morning. Winds could gust as high as 18 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 62. North northeast wind around 8 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Scattered showers, mainly before noon. Mostly sunny, with a high near 74. Northeast wind 8 to 10 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Scattered showers after noon. Widespread haze. Mostly sunny, with a high near 78. East wind 5 to 10 mph becoming west southwest in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Widespread haze. Mostly cloudy, with a low around 60. Light and variable wind. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Isolated showers after noon. Widespread haze. Mostly sunny, with a high near 78. West northwest wind 5 to 7 mph becoming calm in the afternoon. Chance of precipitation is 20%.

Waimea

Today: Scattered showers. Widespread haze. Partly sunny, with a high near 73. Windy, with a northeast wind around 25 mph, with gusts as high as 40 mph. Chance of precipitation is 30%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Isolated showers after midnight. Widespread haze. Partly cloudy, with a low around 51. Windy, with an east wind 21 to 24 mph, with gusts as high as 34 mph. Chance of precipitation is 20%.

Tuesday: Isolated showers before noon. Widespread haze. Mostly sunny, with a high near 73. Windy, with an east wind 18 to 24 mph, with gusts as high as 34 mph. Chance of precipitation is 20%.

Kohala

Today: Showers likely, mainly before noon. Mostly cloudy, with a high near 69. Very windy, with an east wind around 31 mph, with gusts as high as 50 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Partly cloudy, with a low around 44. Windy, with an east wind 26 to 30 mph, with gusts as high as 43 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday: Scattered showers. Partly sunny, with a high near 69. Windy, with an east wind 24 to 30 mph, with gusts as high as 43 mph. Chance of precipitation is 50%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Scattered showers, mainly before noon. Widespread haze. Mostly sunny, with a high near 78. Very windy, with an east northeast wind around 31 mph, with gusts as high as 40 mph. Chance of precipitation is 30%.

Tonight: Scattered showers, mainly before midnight. Widespread haze. Partly cloudy, with a low around 66. Windy, with an east northeast wind 26 to 29 mph, with gusts as high as 38 mph. Chance of precipitation is 30%.

Tuesday: Isolated showers after noon. Widespread haze. Mostly sunny, with a high near 78. Windy, with an east northeast wind 26 to 29 mph, with gusts as high as 38 mph. Chance of precipitation is 20%.

Puna

Today: Showers likely, mainly before noon. The rain could be heavy at times. Mostly cloudy, with a high near 73. Northeast wind around 11 mph, with gusts as high as 22 mph. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 60. Breezy, with a north northeast wind around 16 mph, with gusts as high as 23 mph. Chance of precipitation is 50%. New precipitation amounts between a quarter and half of an inch possible.

Tuesday: Scattered showers, mainly before noon. Mostly sunny, with a high near 73. Breezy, with a north northeast wind 15 to 17 mph, with gusts as high as 23 mph. Chance of precipitation is 40%. New precipitation amounts between a quarter and half of an inch possible.

Waikoloa

Today: Widespread haze. Mostly sunny, with a high near 79. Very windy, with an east northeast wind around 31 mph, with gusts as high as 50 mph.

Tonight: Widespread haze. Mostly clear, with a low around 60. Very windy, with an east wind 21 to 31 mph decreasing to 11 to 21 mph in the evening. Winds could gust as high as 50 mph.

Tuesday: Widespread haze. Sunny, with a high near 79. Breezy, with a northeast wind 9 to 15 mph, with gusts as high as 20 mph.

Detailed Forecast

Synopsis

Windy trade winds will persist through Tuesday before a softening trend begins. This comes about as the strong surface high far north of Kauai starts weakening Tuesday. A new surface high may usher in breezy trades to the western part of the region during the second half of the week. A more stable air mass is forecast to build over the islands today as the upper level trough weakens and drift south of the Big Island. A boost in trade wind showers will come during the second half of the week with a front settling near the islands, aided by another upper level disturbance.

Discussion

The widespread heavy showers that occurred across the northern section of the Big Island, including the Hilo and Puna districts during the evening, continues to trend down. There will be showers moving onshore but they are no where close to what occurred earlier in the evening. As conditions start to improve, stars are beginning to appear on the web cams atop Mauna Kea, with a nice layer of snow on the ground. It is difficult to tell how deep this layer of snow is, however. The Winter Advisory has been extended to 10 am HST for the icy and snow covered roads.
Forecast models are suggesting this stable air mass to spread south across the Big Island through out today, reaching near South Point this afternoon. So, it is safe to say that the threat of widespread heavy showers has ended across the flood watch area, and thus, the Flash Flood Watch for parts of the Big Island and for windward Maui is canceled. Should there be any flare ups, they will be short-lived and be dealt with a Flood Advisory.
We are currently seeing a east to west band of scattered showers cutting through the smaller islands. So, it will be a little bit showery this morning, but it should be rather nice and drier this afternoon, especially along the leeward beaches. It will also be rather windy. The balloon sounding out of Lihue this morning and weather radar derived winds from south Kauai is showing 30 to 35 knots at 25 hundred feet already. It is also rather windy across Oahu with winds blowing just below advisory criteria at a couple of locations. With the trades forecast to strengthen through the coming hours and peaking this afternoon, the Wind Advisory is extended to Oahu and Kauai. This Wind Advisory is good to until 6 pm HST this afternoon. Further extension of the advisory is highly possible, through tonight. The weather system responsible for the windy trades, a strong 1043 mb surface high, is located 1250 miles north-northeast of Kauai this morning. In the next 24 hours, this high is forecast to drift south, closer to the islands, but weakening slightly as well. By Tuesday night, this high will be taken over by another strong high that will be drifting southeastward through Thursday. This may bring a shift to the breezy trades from Maui and the Big Island to the western part of the island chain.
During the second half of the week, models are in agreement for a band of showers to move through the islands Wednesday evening. Wetter conditions moves in Thursday through at least Friday due to a front settling near the islands from the north. This front will be aided by an upper level trough.

Aviation

Strong high pressure to the distant N will support very strong trade winds while a weakening trough aloft keeps the island atmosphere somewhat unstable in the short term, most notably near Maui and the Big Island. The recent steady stream of windward showers is expected to diminish through the day as the trough aloft slides S of the islands, and incoming moisture diminishes.
AIRMET TANGO for moderate lee turbulence remains posted, and now includes a mention of isolated areas of severe turbulence. TANGO also includes mention of localized sustained strong surface winds of 30 kt. AIRMET SIERRA is posted for mountain obscuration on the windward slopes of Maui and the Big Island.

Marine

Strong high pressure to the north of the state will produce areawide strong to local gale force trade winds across our near- shore waters. Persistent, strong trades over the past several days have generated fully- developed, rough seas around the islands and this rough sea state will hold through Tuesday. Trades achieving or frequently gusting to gale through the windier channels and bays surrounding Maui County and the Big Island has a Gale Warning posted for the Pailolo and Alenuihaha Channels, Maalaea Bay and those waters south of the Big Island. A Small Craft Advisory (SCA) remains in effect for all of the remaining coastal waters due to the combination of strong trades and high seas. These hazardous maritime conditions will persist into Tuesday as high pressure dominates north of the islands. This high will be weakened by the passage of a North Pacific cold front late Tuesday and Wednesday. This will result in a short term decline in both trades and seas and lead to an anticipated cancellation of this long running SCA over most, if not all, coastal waters by Wednesday evening. As high pressure moves in from the west and travels north of the islands later this week, trades will restrengthen to moderate to locally strong magnitudes from late Thursday into the weekend.
Trade wind-driven rough seas will maintain high surf along east- facing shores for another couple of days. Although east swell is subtly lowering, these swells in tandem with easterly wind waves will continue to justify the ongoing High Surf Advisory (HSA) for the east-facing shores of Kauai, Oahu, Molokai, Maui and the Big Island. Areawide trades will remain strong to near gale force magnitudes within the windier channels and bays through Tuesday. The HSA will be in effect to account for greater than 8 foot surf heights along most eastern exposures through Tuesday evening or early Wednesday morning.
Surf will remain below HSA criteria on all other shores through much of the week. Sunday’s small, moderate period northwest swells are on the decline today and Tuesday. A larger, long period northwest swell arriving late Wednesday will lift recent well below average north and west-facing shoreline surf back to near advisory levels Thursday and Friday. These swells will shift more north and decline through next weekend. Surf along south-facing shores will remain at or slightly above winter averages through Tuesday due to a combination of both small south-southwest swells and trade wind wave and swell wrap.

HFO Watches/Warnings/Advisories

Wind Advisory until 6 PM HST this evening for Kauai, Oahu, Molokai, Lanai, Kahoolawe, Maui Windward West, Maui Leeward West, Maui Central Valley, Windward Haleakala, Leeward Haleakala, South Big Island, Big Island North and East, Kohala.
High Surf Advisory until 6 PM HST Tuesday for Kauai Windward, Oahu Koolau, Olomana, Molokai Windward, Maui Windward West, Windward Haleakala, South Big Island, Big Island North and East.
Winter Weather Advisory until 10 AM HST this morning for Big Island Summits.
Gale Warning until 6 PM HST Tuesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 PM HST Tuesday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters, Big Island Windward Waters.

Data Courtesy of NOAA.gov