Hilo

Today: Showers likely, mainly before noon. Partly sunny, with a high near 83. Calm wind becoming east 5 to 9 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely. Mostly cloudy, with a low around 63. Calm wind becoming west southwest around 6 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Monday: Showers likely, mainly before noon. Mostly cloudy, with a high near 83. Light and variable wind becoming east 5 to 8 mph in the afternoon. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Kona

Today: Scattered showers after noon. Mostly sunny, with a high near 84. West northwest wind 5 to 7 mph becoming calm in the afternoon. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Isolated showers. Partly cloudy, with a low around 63. Calm wind becoming east northeast around 5 mph. Chance of precipitation is 20%.

Monday: Scattered showers, mainly after noon. Mostly sunny, with a high near 83. Light and variable wind becoming west 5 to 10 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Waimea

Today: Scattered showers, mainly before noon. Partly sunny, with a high near 76. Breezy, with a northeast wind 15 to 21 mph, with gusts as high as 29 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Scattered showers. Mostly cloudy, with a low around 52. Breezy, with an east northeast wind 7 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.

Monday: Scattered showers. Partly sunny, with a high near 75. North northeast wind 5 to 10 mph becoming light and variable in the afternoon. Chance of precipitation is 50%. New precipitation amounts between a tenth and quarter of an inch possible.

Kohala

Today: Showers likely, mainly before noon. Mostly cloudy, with a high near 69. Breezy, with an east northeast wind 15 to 22 mph, with gusts as high as 31 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Tonight: Showers likely, mainly before midnight. Mostly cloudy, with a low around 44. Breezy, with an east wind 11 to 16 mph becoming light. Winds could gust as high as 22 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

Monday: Showers likely, mainly after noon. Mostly cloudy, with a high near 67. East wind around 6 mph becoming light and variable. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

South Big Island

Today: Isolated showers before noon. Mostly sunny, with a high near 84. Windy, with an east wind 21 to 26 mph decreasing to 15 to 20 mph in the afternoon. Winds could gust as high as 34 mph. Chance of precipitation is 20%.

Tonight: Isolated showers after midnight. Partly cloudy, with a low around 69. Breezy, with an east wind 11 to 16 mph, with gusts as high as 21 mph. Chance of precipitation is 20%.

Monday: Isolated showers. Mostly sunny, with a high near 83. Breezy, with an east wind 11 to 16 mph, with gusts as high as 21 mph. Chance of precipitation is 20%.

Puna

Today: Showers likely, mainly before noon. Mostly cloudy, with a high near 80. Northwest wind 7 to 11 mph becoming east northeast in the afternoon. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

Tonight: Showers likely. Mostly cloudy, with a low around 61. East northeast wind 5 to 7 mph becoming calm after midnight. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

Monday: Showers likely. Mostly cloudy, with a high near 81. Light and variable wind becoming east 5 to 10 mph in the afternoon. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

Waikoloa

Today: Sunny, with a high near 81. Breezy, with an east southeast wind 7 to 15 mph becoming northeast in the morning. Winds could gust as high as 21 mph.

Tonight: Mostly clear, with a low around 62. East wind 5 to 9 mph becoming light after midnight.

Monday: Scattered showers after noon. Mostly sunny, with a high near 81. Light and variable wind becoming west northwest 5 to 8 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.

Detailed Forecast

Synopsis

Moderate to locally breezy trade wind weather will continue today as a high pressure ridge lingers north of the state. Clouds and passing showers will favor windward and mountain areas. Winds will weaken to light and variable on Monday as a cold front approaches the islands from the northwest. Lighter large scale winds will allow local scale land and sea breezes to develop through Wednesday. The cold front is forecast to stall and dissipate near Kauai during this period. A new high pressure system moving into the region will cause trade winds to gradually strengthen from Thursday onward.

Discussion

A high pressure system north of the state will keep moderate to locally breezy trade winds in the forecast for one more day. Passing clouds and showers shown on satellite and radar imagery will tend to favor windward and mountain slopes of all islands. An upper level low just south of the islands and cold temperatures aloft will keep these passing showers in the forecast for one more day.
A weakening cold front approaching the islands from the northwest on Monday will break down the high pressure ridge north of the state and causing wind speeds to weaken. Lighter winds are forecast from Monday through Wednesday as this weak frontal trough stalls out near Kauai. Showers will persist along this dissipating frontal band. These lighter large scale winds will allow local scale land and sea breezes to develop over each island. Weather patterns will shift with converging sea breezes and day time island heating building clouds and a few showers over island mountain and interior sections. The upper low south of the islands will be drawn northeastward from Monday night into Tuesday, producing a slight increase in shower activity during that time period.
There remains a bit of uncertainty on where this frontal shower band will land in next week’s forecast. Long range models continue to show significant run to run differences on the final location of this dissipating frontal trough. However, both the American and European global models are showing prefrontal shower bands developing over the smaller islands from Kauai to Maui in the Tuesday and Wednesday time periods. Rainfall amounts along the either the frontal or pre-frontal shower bands remain modest in all our forecast guidance tools.
A migratory high drifting from west to east across the Central Pacific basin will cause trade winds to gradually return to the region from Thursday onward. Brief passing showers and clouds will favor windward and mountain slopes of each island into next weekend.

Aviation

High pressure north of the state will keep moderate to breezy trade winds in place today, before beginning to ease tonight as a front approaches from the west. Clouds and showers will favor windward slopes and coasts, with a few showers spilling leeward from time to time. Occasional MVFR cigs/vsbys will be possible in showers over windward locales, otherwise prevailing VFR conditions are expected.
AIRMET Sierra is in effect for mountain obscuration across windward sections of Oahu, Molokai, Maui and the Big Island. Conditions should improve here later this morning.
AIRMET TANGO remains in effect for low level turbulence over and downwind of the terrain of all islands. This AIRMET will likely continue through the day. AIRMET Tango is also in effect for moderate upper level turbulence between FL270 and FL450. This AIRMET will likely continue through the day as well.

Marine

Surface high pressure centered far northeast of Oahu is producing a tight enough pressure gradient back toward the islands to maintain moderate to locally strong trade winds today. A recent ASCAT satellite pass observed Small Craft Advisory (SCA) level winds across the Kaiwi Channel and leeward Maui waters. Thus, the SCA has been expanded in area and extended in time to include these waters through this afternoon along with those windier waters surrounding Maui County and south of the Big Island into Monday morning. Trades will weaken and veer more southerly Monday in response to an approaching front from the northwest of the island chain. The surface ridge northeast of the state will move further east of the islands Tuesday and Wednesday with the weakening front dissipating and stalling near the western islands. This will result in gentle and variable mid week breezes. High pressure passing north of the state Thursday will reestablish trades that will strengthen back to moderate to fresh magnitudes Friday.
Surf along all Hawaiian shores will be well under high surf advisory thresholds the next several days. North facing shore surf will remain very low through Monday with only a small background north swell. The next appreciable west northwest swell will arrive Monday night and Tuesday and this will peak surf in the moderate range. This swell will transition to more northwest Wednesday and then north northwest on Thursday. As this swell diminishes, another potentially larger late week northwest swell may peak weekend surf into the double digits (face values in feet) along northern and western exposures. Multi short and long period south southwest swell energy along southern coasts will continue to support near to slightly under seasonable south shore surf today. Eastern shoreline surf will also remain around spring season averages through Monday but will drop off through mid week as trade winds weaken over and upstream of the state.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Monday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 PM HST this evening for Kaiwi Channel, Maui County Leeward Waters.

Data Courtesy of NOAA.gov