Photo Credit: James Grenz

Hilo

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 78 to 84 near the shore to 65 to 71 at 4000 feet. Light winds becoming southeast up to 10 mph in the afternoon. Chance of rain 40 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 61 to 69 near the shore to around 55 at 4000 feet. Southwest winds up to 10 mph. Chance of rain 20 percent.

Saturday: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 77 to 83 near the shore to 64 to 71 at 4000 feet. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 50 percent.

Kona

Today: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 84 near the shore to around 68 near 5000 feet. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Lows 68 to 73 near the shore to 48 to 54 near 5000 feet. Light winds.

Saturday: Mostly cloudy. Isolated showers in the afternoon. Highs 81 to 86 near the shore to around 68 near 5000 feet. Light winds becoming west around 10 mph in the afternoon. Chance of rain 20 percent.

Waimea

Today: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 66 to 83. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Lows 61 to 68 near the shore to 54 to 61 near 3000 feet. Light winds.

Saturday: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 65 to 83. Light winds. Chance of rain 50 percent.

Kohala

Today: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 66 to 83. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Lows 61 to 68 near the shore to 54 to 61 near 3000 feet. Light winds.

Saturday: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 65 to 83. Light winds. Chance of rain 50 percent.

South Big Island

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs around 82 near the shore to around 67 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Lows around 71 near the shore to around 50 near 5000 feet. Northeast winds up to 10 mph.

Saturday: Mostly cloudy. Isolated showers in the afternoon. Highs around 82 near the shore to around 66 near 5000 feet. East winds up to 10 mph shifting to the southeast in the afternoon. Chance of rain 20 percent.

Puna

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 78 to 84 near the shore to 65 to 71 at 4000 feet. Light winds becoming southeast up to 10 mph in the afternoon. Chance of rain 40 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 61 to 69 near the shore to around 55 at 4000 feet. Southwest winds up to 10 mph. Chance of rain 20 percent.

Saturday: Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 77 to 83 near the shore to 64 to 71 at 4000 feet. Light winds becoming east up to 10 mph in the afternoon. Chance of rain 50 percent.

Waikoloa

Today: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 81 to 86 near the shore to 65 to 72 above 4000 feet. Light winds. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Lows around 71 near the shore to 48 to 54 above 4000 feet. Light winds.

Saturday: Mostly cloudy. Isolated showers in the afternoon. Highs 80 to 87 near the shore to 66 to 71 above 4000 feet. Light winds becoming northwest up to 10 mph in the afternoon. Chance of rain 20 percent.

Detailed Forecast

Synopsis

A stable land and sea breeze pattern will continue in a weak background east to southeasterly wind flow through Saturday. A weak cold front will approach the islands from the northwest this weekend increasing moisture and instability from Saturday night through Sunday. Expect higher chances for showers across the state as background winds become more southerly, increasing the potential for heavy rainfall and isolated thunderstorms from Saturday evening into Monday morning. Drying trends are forecast from late Monday through Wednesday as more stable trade winds return to the region.

Discussion

Satellite and radar imagery this morning continues to show fairly stable conditions across the region with a few showers drifting into the eastern and southeastern slopes of each island on the weak background east to southeast winds. A subtropical jet stream north of the state continues to produce high level cirrus clouds, enhancing sunrise and sunset colors through the weekend.
Weak background easterly winds are becoming more southeasterly this morning with local scale land and sea breeze winds expected over each island. An upper level ridge will keep weather conditions fairly stable, minimizing shower potential into Saturday afternoon. Weather conditions start to change from Saturday evening onward as a weak cold front approaches the islands from the northwest direction.
South to southwest winds aloft will help bring increasing moisture and instability from the deeper tropics into the area from Saturday evening through Monday morning. The weakening front will diminish into a trough as it drifts into the western islands from late Sunday into Monday. An upper level trough associated with the weak front will pass through the region enhancing shower activity, with periods of heavy showers and isolated thunderstorms possible for the Saturday evening to Monday morning time period. The highest threat for heavy rainfall and thunderstorms are forecast on Sunday and Sunday night. Chances for heavy rainfall will diminish from west to east on Monday as the upper level trough passes through the islands.
Drier trends are forecast as light to moderate northeast to east trade winds return from Monday through Thursday. High pressure building in aloft during this time period will tend to minimize shower activity through much of next week.

Aviation

Land breezes have brought about clearing of low clouds beneath an extensive canopy of high cirrus. Light SSE flow may allow a few low clouds or isolated showers to drift onshore along the immediate coastline, but prevailing VFR is expected throughout the forecast period. Sea breezes will bring renewed inland cloud development with very isolated shower activity.
AIRMET Tango is in effect for moderate upper level turbulence between FL250 and FL400.

Marine

A ridge axis, extending southwest from high pressure centered off the California coast, is laying across the far northern offshore waters. A cold front moving towards this ridge is becoming stationary approximately 500 miles north northwest of Oahu. Thus, near calm to gentle east southeast breezes are in place north of 20N. The pressure gradient is tight enough toward the ITCZ to result in stronger moderate to fresh northeast to easterly trade flow across waters south of 20N. A cold front will be approaching the area from the northwest today and Saturday that will generally veer gentle to moderate breezes more southeasterly out ahead of the boundary. This front will weaken as it enters our northern waters and is forecast to reach the central Hawaiian waters as a diffuse boundary Sunday. The weekend weather pattern associated with this stalling front may become more unsettled as there will be higher probabilities for areas of heavy rain and isolated thunderstorms. Light winds will become north northeast behind the front into early next week and then transition back to primarily gentle trades by Tuesday.
An upward trend in surf will occur today along the smaller island exposed north and west facing shores with the arrival of a moderate size, medium period northwest swell. This swell is being picked up by the northwest offshore buoys early this morning. The north and west shores of Kauai and Oahu should begin experiencing elevated surf by late morning and late afternoon, respectively. Surf will peak along north and west shores later today through Saturday and then hold on Sunday. On the heels of this swell will come another similar moderate size, medium period north swell late Saturday and early Sunday due to it originating from a more local short north fetch source behind a proximity cold front. This should peak north and west facing shore surf near to just shy of High Surf Advisory levels Sunday and Monday. Very small, long period background energy will keep surf along south facing shores on the small side throughout the forecast period. Eastern shore chop will remain small through the rest of the week due to these lighter winds over and upstream of the islands.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov