Photo Credit: James Grenz

Hilo

Today: Cloudy. Showers and isolated thunderstorms in the morning, then numerous showers and isolated thunderstorms in the afternoon. Highs around 84 near the shore to 68 to 73 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 80 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 66 near the shore to around 52 at 4000 feet. Light winds. Chance of rain 40 percent.

Thursday: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 84 near the shore to 68 to 73 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Kona

Today: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers and isolated thunderstorms in the afternoon. Highs 81 to 86 near the shore to around 68 near 5000 feet. Southwest winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows 67 to 73 near the shore to around 53 near 5000 feet. Light winds. Chance of rain 20 percent.

Thursday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 81 to 86 near the shore to around 68 near 5000 feet. Light winds. Chance of rain 40 percent.

Waimea

Today: Mostly cloudy. Numerous showers and isolated thunderstorms in the morning, then scattered showers and isolated thunderstorms in the afternoon. Highs around 82 near the shore to 68 to 79 near 3000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 66 near the shore to 54 to 60 near 3000 feet. Light winds. Chance of rain 40 percent.

Thursday: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 82 near the shore to 68 to 79 near 3000 feet. Light winds. Chance of rain 50 percent.

Kohala

Today: Mostly cloudy. Numerous showers and isolated thunderstorms in the morning, then scattered showers and isolated thunderstorms in the afternoon. Highs around 82 near the shore to 68 to 79 near 3000 feet. East winds up to 10 mph. Chance of rain 70 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 66 near the shore to 54 to 60 near 3000 feet. Light winds. Chance of rain 40 percent.

Thursday: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 82 near the shore to 68 to 79 near 3000 feet. Light winds. Chance of rain 50 percent.

South Big Island

Today: Mostly sunny in the morning, then partly sunny with scattered showers and isolated thunderstorms in the afternoon. Highs around 85 near the shore to around 72 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Isolated showers after midnight. Lows around 68 near the shore to around 51 near 5000 feet. Light winds. Chance of rain 20 percent.

Thursday: Sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 85 near the shore to around 72 near 5000 feet. South winds around 10 mph. Chance of rain 40 percent.

Puna

Today: Cloudy. Showers and isolated thunderstorms in the morning, then numerous showers and isolated thunderstorms in the afternoon. Highs around 84 near the shore to 68 to 73 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 80 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 66 near the shore to around 52 at 4000 feet. Light winds. Chance of rain 40 percent.

Thursday: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 84 near the shore to 68 to 73 at 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Waikoloa

Today: Mostly sunny in the morning then becoming mostly cloudy. Scattered showers and isolated thunderstorms. Highs around 85 near the shore to 69 to 75 above 4000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.

Tonight: Mostly clear. Lows 68 to 73 near the shore to 49 to 56 above 4000 feet. Light winds.

Thursday: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 85 near the shore to 69 to 75 above 4000 feet. Light winds. Chance of rain 50 percent.

Detailed Forecast

Synopsis

Moderate to breezy trade winds from a high pressure system far north of the islands will become blocked by a passing disturbance moving through the region this week. Lighter winds over the next three days will allow local scale land and sea breezes to develop. A few showers will form over island mountain and interior sections each afternoon. Trade winds will restrengthen from Friday into the weekend as the disturbance weakens and drifts northward, and the high pressure ridge builds back in over the region. A remnant trough associated with former Tropical Cyclone Georgette will drift westward through the islands enhancing shower activity from Monday morning into Tuesday.

Discussion

The water vapor satellite imagery continues to show an upper level low just north of the Big Island this morning. Satellite cloud tops temperature estimates near the center of this cold core low are around 20,000 feet and a few thunderstorms are already developing around this system. The 2 AM HST upper air balloon sounding from Hilo this morning shows the temperature inversion height has lifted to around 11,000 feet. Isolated thunderstorms remain in the forecast for the Big Island and Maui region through this afternoon. A combination of colder temperatures aloft and upper level forcing from the passing low will continue to allow deeper clouds to form today across the state. Local radar imagery also supports this forecast with scattered to numerous showers drifting into each island on the waning trade winds in a more unstable environment.
The large scale picture remains the same with a large and strong high pressure center located far north of the Hawaiian Islands through the seven day forecast period. The unstable upper level low near Maui and the Big Island will continue to enhance shower activity for all islands today. A surface trough, induced by the upper level low, will weaken the trade winds through early Friday morning. Light large scale winds will allow local scale land and sea breezes to strengthen over each island during this time period. Sea breeze winds will move cloud cover and shower activity into island mountain and interior sections each day through Friday. Land breezes will develop around sunset and clear out cloud cover each night. Isolated thunderstorms are possible near Maui and the Big Island through this afternoon.
Friday is the transition day with the high pressure ridge building back into the region as the upper low weakens and lifts northward. Moderate trade winds are forecast to return with lingering sea breezes by Friday afternoon. Trade winds will strengthen into the moderate to breezy range on Saturday and Sunday. Cloud and shower coverage will return to the more typical windward and mountain areas. Stronger winds and drying trends may produce near critical fire weather conditions for some leeward areas by Sunday. Otherwise trade winds continue to blow through the first half of next week.
An easterly wave, the remnants of former Tropical Cyclone Georgette, will drift westward into the Hawaii region starting Monday morning over the Big Island and Maui. Additional clouds and enhanced showers will spread westward across the state reaching Kauai on Tuesday.
Long range guidance continues to show a tropical low passing south of the Big Island around the middle of next week. If this low continues to pass south of the islands, as the global models suggest, then we could see increasing trade winds due to stronger surface pressure gradients during this time period.

Aviation

The trade winds will continue to gradually ease through this evening. An upper-level low northeast of the Big Island will lift slowly northward through tonight, and produce unstable atmospheric conditions over the eastern end of the island chain. The close proximity of this feature may allow isolated thunderstorms to develop near east Maui and the Big Island through this afternoon. Otherwise, low clouds and showers carried by the low-level trade wind flow will favor windward and mauka areas. There may be brief periods of MVFR cigs/vis in low clouds and showers along some windward facing slopes and coasts.
By this afternoon, the weaker trade winds may allow the development of localized sea breeze circulations over many leeward and interior sections of the island chain. This may produce increasing cloud cover and a chance of brief showers across leeward and interior areas later today.
No AIRMETs are currently in effect, and none are anticipated through this morning. There is a chance that AIRMET Sierra for mountain obscuration might be needed this afternoon for portions of the Big Island or Maui.

Marine

Trade winds will remain very weak the next few days. This is in response to the approach of an upper low and associated surface trough to the east. This will relax the lower level pressure gradient as the low tracks north and west of the island chain… ultimately maintaining mid to late week gentle easterlies. This low will increase the probability of isolated thunderstorms over Maui and Big Island's windward waters today. Trades will strengthen over the weekend as high pressure builds in northeast of the area.
A fading small south swell will continue to fall through the day with just small background south swells expected during the remainder of the week. East facing shores will see a gradual increase in surf the next few days. This will be in response to the arrival and passage of a small, medium period east swell from recent eastern Pacific tropical cyclone activity.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov