Hilo

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 84 to 90 near the shore to around 74 at 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 67 to 74 near the shore to around 56 at 4000 feet. Southwest winds up to 10 mph. Chance of rain 70 percent.

Sunday: Cloudy with showers. Highs 81 to 87 near the shore to around 71 at 4000 feet. East winds up to 10 mph. Chance of rain 80 percent.

Kona

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 82 to 87 near the shore to around 70 near 5000 feet. Light winds. Chance of rain 30 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows 70 to 75 near the shore to around 57 near 5000 feet. Light winds. Chance of rain 20 percent.

Sunday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 82 to 87 near the shore to around 70 near 5000 feet. Light winds. Chance of rain 50 percent.

Waimea

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs around 84 near the shore to 76 to 81 near 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows around 69 near the shore to 57 to 64 near 3000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Sunday: Mostly cloudy. Numerous showers in the morning, then showers in the afternoon. Highs around 82 near the shore to 73 to 80 near 3000 feet. East winds 10 to 15 mph. Chance of rain 80 percent.

Kohala

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs around 84 near the shore to 76 to 81 near 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows around 69 near the shore to 57 to 64 near 3000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Sunday: Mostly cloudy. Numerous showers in the morning, then showers in the afternoon. Highs around 82 near the shore to 73 to 80 near 3000 feet. East winds 10 to 15 mph. Chance of rain 80 percent.

South Big Island

Today: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 86 near the shore to around 74 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy in the evening then becoming mostly clear. Isolated showers. Lows around 72 near the shore to around 55 near 5000 feet. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Sunday: Mostly sunny with isolated showers in the morning, then mostly cloudy with numerous showers in the afternoon. Highs around 86 near the shore to around 75 near 5000 feet. East winds 10 to 15 mph. Chance of rain 70 percent.

Puna

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 84 to 90 near the shore to around 74 at 4000 feet. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Scattered showers in the evening, then numerous showers after midnight. Lows 67 to 74 near the shore to around 56 at 4000 feet. Southwest winds up to 10 mph. Chance of rain 70 percent.

Sunday: Cloudy with showers. Highs 81 to 87 near the shore to around 71 at 4000 feet. East winds up to 10 mph. Chance of rain 80 percent.

Waikoloa

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 83 to 88 near the shore to 69 to 76 above 4000 feet. Light winds becoming northwest up to 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows around 74 near the shore to 53 to 61 above 4000 feet. Southeast winds up to 10 mph in the evening becoming light. Chance of rain 20 percent.

Sunday: Sunny in the morning then becoming partly sunny. Scattered showers. Highs 83 to 89 near the shore to 69 to 76 above 4000 feet. Light winds. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Light trade winds will allow sea breezes to develop starting later this morning, which will produce clouds and showers over most interior and leeward sections this afternoon. Moderate trade winds are expected to return across the state starting Sunday. A surface trough combined with an area of enhanced moisture moving from east to west across the island chain will likely cause an increase in trade showers on Sunday, especially along windward facing slopes and coasts. Expect a more typical pattern of brief trade showers along windward sections during the late night and early morning hours from Monday through Wednesday. The trade winds are expected to weaken again starting late Thursday.

Discussion

A 1008 mb surface low is evident near 34N 159W, or about 875 miles north of Honolulu. A weak surface trough, which is associated with this low, extends down to within 270 miles northwest of Lihue. Elsewhere, a weak northeast to southwest oriented surface ridge is about 360 miles north of Hilo. The areas of lower pressure continue to disrupt the pressure gradient across the main Hawaiian Islands early this morning, which is keeping our usual trade wind flow much weaker than normal. This allowed local land breezes to develop across each of the individual islands last evening, which resulted in the dissipation of most low clouds and showers over the state overnight. The main exception is some low clouds and isolated showers lingering near the coast of the leeward Big Island north of Kailua-Kona. Note that an upper-level jet in the vicinity of the islands is transporting patches of high clouds rapidly from west to east across portions of the island chain this morning.
Aloft, there is an upper-level trough just north of the state. This feature likely enhanced the coverage and intensity of showers across portions of Oahu and Molokai Friday afternoon. The forecast guidance shows that the upper-level trough will shift north-northwestward away from the western islands later today. However, the upper-level jet is expected to remain in the area, and will likely transport some high clouds across portions of the island chain this weekend.
The weak background trade wind flow will once again allow the local sea breezes to develop this afternoon. There may be fewer showers today, since the influence of the upper-level trough will likely diminish as it departs the area. We still expect clouds and some showers over leeward and interior sections of the islands where convergence of sea breeze circulations occurs. The nighttime land breezes will then clear out most of the clouds and showers over most of the smaller islands tonight. Trade showers may begin to increase over the windward Big Island later tonight.
By Sunday, the forecast guidance shows the surface trough, which is currently northwest of Kauai, will push west. The subtropical ridge will build north of the area and will allow moderate trade winds to return through early next week. The guidance also shows that a weak surface trough and a slightly enhanced area of moisture will move into the area from the east as the trade winds return. This may increase the coverage of low clouds and showers, especially over windward and mauka areas from Sunday through early Monday morning. The enhanced showers associated with this surface trough are expected to move west of all islands sometime after dawn Monday morning. After that, expect mainly brief trade showers through Wednesday in this moderate trade wind pattern, primarily affecting windward and mauka areas in the overnight to early morning hours. Leeward areas of the smaller islands will likely see fairly dry conditions from Monday through Wednesday, while afternoon clouds and showers are expected over the upslope sections of the leeward Big Island.
Another front approaching Hawaii from the north is forecast to weaken the surface ridge again, with lighter trade winds expected starting late Thursday. This front may move down to a position just northwest of the state next weekend, which may cause the light background flow to be from a southeast to south direction.

Aviation

Weak trade wind flow continues through the forecast period. Clouds and showers will tend to favor windward and mauka locations this morning. Sea breeze clouds and isolated showers look to redevelop across sheltered leeward areas this afternoon/evening then diminish shortly after sunset.
Expect mainly VFR conditions through the forecast period, with brief MVFR conditions possible under passing showers later today. The exception to this remains portions of the Big Island where scattered MVFR cigs continue to linger this morning resulting in tempo mountain obscuration. AIRMET Sierra is currently in effect for these areas, but as cigs continue to lift and scatter this morning will likely cancel it with the upcoming issuance.

Marine

No significant changes to the forecast this morning. Winds are expected to trend upwards early next week, with some of the typical windier areas approaching Small Craft Advisory levels.
A ridge to the northeast and a weak front to the north through northwest will help to keep trade winds light this morning. As the front dissipates today, the high pressure system will strengthen. This will allow the trade winds to return to moderate levels by Sunday. Models show the strongest winds will be Monday and Tuesday.
A small, short-period southeast swell will linger through Sunday. A series of small, mid to long period south swells will move across the area through Monday night with a slightly larger long period south swell expected Tuesday through Thursday. A slightly larger short-period north swell is expected today and tomorrow, with a longer period northwest swell filling in late Monday through Tuesday. Expecting that swell to then lower gradually Wednesday and Thursday with the period becoming rather short. Short period choppy surf will remain rather small through the forecast period as trade winds over and upwind of the state remain on the lighter side.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov