Hawaii County climate forecast is September 22, 2021

Hilo

Today: Partly sunny with a few showers. Highs from 80 to 86 near shore to 68 to 73 at 4000 feet. Northeast winds up to 15 miles per hour. Chance of rain 40 percent.

Tonight: Mostly cloudy with showers likely. Lows of around 68 near the shore to around 54 at 4000 feet. West winds up to 10 km / h. Chance of rain 70 percent.

Thursday: Partly sunny. Showers probably in the morning, then scattered showers in the afternoon. Highs from 80 to 86 near shore to 68 to 73 at 4000 feet. In the afternoon, the north wind blows at up to 24 km / h to the northeast. Chance of rain 70 percent.

Kona

Today: Mostly sunny in the morning, then partly sunny in the afternoon with a few showers. Highs from 86 near shore to 73 near 5000 feet. West winds up to 10 km / h. Chance of rain 20 percent.

Tonight: Mostly cloudy with a few showers in the evening, then partly cloudy with a few showers after midnight. Lows of 68 to 74 near shore to about 54 near 5000 feet. Breeze. Chance of rain 40 percent.

THE ARTICLE CONTINUES BELOW THE ADVERT

Thursday: Mostly sunny in the morning, then partly sunny in the afternoon with a few showers. Highs from 86 near shore to 73 near 5000 feet. Breeze. Chance of rain 40 percent.

Waimea

THE ARTICLE CONTINUES BELOW THE ADVERT

Today: Mostly sunny in the morning, then partly sunny. Airy. Isolated showers. Heights from 82 near shore to 73 to 80 near 3000 feet. East winds 10 to 20 miles per hour. Chance of rain 20 percent.

Tonight: Mostly cloudy with a few showers. Lows of 67 near shore to 54 to 61 near 3000 feet. East winds 10 to 15 miles per hour. 50 percent chance of rain.

Thursday: windy. Partly sunny with a few showers. Heights from 82 near shore to 73 to 80 near 3000 feet. East winds 10 to 20 miles per hour. 50 percent chance of rain.

Kohala

THE ARTICLE CONTINUES BELOW THE ADVERT

Today: Mostly sunny in the morning, then partly sunny. Airy. Isolated showers. Heights from 82 near shore to 73 to 80 near 3000 feet. East winds 10 to 20 miles per hour. Chance of rain 20 percent.

Tonight: Mostly cloudy with a few showers. Lows of 67 near shore to 54 to 61 near 3000 feet. East winds 10 to 15 miles per hour. 50 percent chance of rain.

Thursday: windy. Partly sunny with a few showers. Heights from 82 near shore to 73 to 80 near 3000 feet. East winds 10 to 20 miles per hour. 50 percent chance of rain.

Southern big island

Today: Mostly sunny. Airy. A few showers in the afternoon. Altitudes around 85 near shore to 74 near 5000 feet. East wind up to 25 km / h. Chance of rain 20 percent.

Tonight: Partly cloudy. Airy. Isolated showers in the evening. Lows of about 68 near shore to about 53 near 5000 feet. Northeast winds up to 20 miles per hour. Chance of rain 20 percent.

Thursday: windy. Mostly sunny in the morning, then partly sunny in the afternoon with a few showers. Altitudes around 85 near shore to 74 near 5000 feet. East wind up to 20 km / h. Chance of rain 20 percent.

feedback

Today: Partly sunny with a few showers. Highs from 80 to 86 near shore to 68 to 73 at 4000 feet. Northeast winds up to 15 miles per hour. Chance of rain 40 percent.

Tonight: Mostly cloudy with showers likely. Lows of around 68 near the shore to around 54 at 4000 feet. West winds up to 10 km / h. Chance of rain 70 percent.

Thursday: Partly sunny. Showers probably in the morning, then scattered showers in the afternoon. Highs from 80 to 86 near shore to 68 to 73 at 4000 feet. In the afternoon, the north wind blows at up to 24 km / h to the northeast. Chance of rain 70 percent.

Waikoloa

Today: Mostly sunny. Airy. A few showers in the afternoon. Heights from 85 near shore to 69 to 75 over 4000 feet. Northeast winds up to 25 miles per hour. Chance of rain 20 percent.

Tonight: airy. Partly cloudy with a few showers. Lows of 69 to 74 near shore to 50 to 57 over 4000 feet. Southeasterly winds up to 20 miles per hour. Chance of rain 20 percent.

Thursday: Mostly sunny. Airy. A few showers in the afternoon. Heights from 85 near shore to 69 to 75 over 4000 feet. Northeast winds up to 20 miles per hour. Chance of rain 20 percent.

summary

The high pressure in the north of the state will keep moderate to stormy trade winds in place until early next week. Rather dry conditions are expected this morning, with more typical trade winds with windward and mauka showers and occasional sloshing down leeward, which will return later this through Saturday. A low pressure valley sliding in the south of the state could bring choppier conditions in windward areas, particularly over the Big Island and Maui, Saturday night through early next week.

discussion

Currently on the surface, a high pressure ridge about 650 miles north of Kauai continues to drive moderate to breezy trade winds across the island chain in the early morning. Infrared satellite images show partly to mostly cloudy conditions in windward areas with clear to partly cloudy skies in most of the leeward areas. Radar images show some light showers moving into windward sections of the Big Island with very little or no shower activity in the rest of the state. The top short-term concerns revolve around trade wind trends and the likelihood of rain for the next few days.
The high pressure ridge north of the islands should keep breezy trade winds in place today, with the trade winds tending to moderate levels tonight and Thursday as a cold front approaches and grinds to a halt in the far northwest. Moderate trade winds should then stop Friday and Saturday before they possibly get breezy again on Sunday and Monday as a low pressure valley passes by in the south of the state.
As for the remaining weather details, the UW-CIMSS images of Total Separable Water (PW) show dry air mass over the smaller islands with PW values ​​of 0.9 to 1.1 inches. Slightly higher PW values ​​of 1.1 to 1.3 inches are present over and upstream of the Big Island. That should translate into fairly dry conditions across much of the state this morning. The breezy trades will likely bring a few light showers to the windward areas, with coverage being highest over the windward Big Island. The air mass upstream of the islands should humidify by late afternoon, which means a return to the more typical trade wind weather. Bands of clouds and showers then move across the islands from tonight to Saturday, with showers favoring the windward and mauka areas, especially at night and in the early morning hours, with some showers at times also affecting the communities downwind.
A surface trough sliding by in the south of the state could bring somewhat more troubled weather to windward areas from Saturday night through Monday, especially over the windward stretches of the Big Island and Maui. The newest 00Z ECMWF has evolved further south with the surface trough position and is now closely linked to the 00Z GFS solution. This suggests that the deepest moisture associated with the trough and the potential for heavier rain will remain in the south of the island chain. We will continue to monitor model trends closely, however, as just a slight shift to the north towards the end of the weekend and early next week could bring heavy rain to the windward stretches of the eastern islands.

aviation

The high pressure in the north of the area is slowly moving east. The feature is sustained to this day and beyond moderate to stormy trade winds across the island chain. Advancing showers on the voyages occasionally produce short MVFR in lower ceilings and visibility, mainly in windward and mauka sections across the state.
An AIRMET for the darkening of the mountains remains in effect for parts of the Big Island on the windward side. This AIRMET may need to be extended until late morning as more clouds and showers are approaching from the east of the island. In addition, an AIRMET has been expanded for moderate turbulence at a low level in the lee of the mountains and will probably remain in place until this afternoon.

marine

The North Pacific has left its summer mode and is showing two storm lows this week driving overlapping swells towards the islands. The first north-northwest swell peaked this early this morning at the coastal PacIOOS buoy near Hanalei, above the predicted level. Expect this trend to continue into the morning hours along the island chain today before gradually subsiding tonight through Thursday.
A major north-northwest swell, associated with a storm force low and currently centered about 2,000 miles northwest, should fill up by Thursday night, Friday’s high (surfing can be done near reference levels along exposed north and west coasts of the smaller islands), then slowly fade into the weekend. Recent satellite data reflected this with a decent area of ​​hurricane / storm winds concentrated in the area within the 315-330 degree band (better energy focused northeast of the state). Altimeter data and SOFAR drifter buoys inside / near the fetch showed a sea state of 28 to 34 ft (slightly larger than the target) last night and this morning.
Surfing along the south-facing coasts will continue into the second half of the week as there is a long south swell. This event should peak around / by Thursday before it turns into the weekend.
Surfing along the east facing coastlines remains small and choppy due to the fresh / heavy trade on-site and just upstream of the state.
The Small Craft Advisory wind will continue throughout the day today (may need to be extended to tonight) across the windier areas and channels from the Kaiwi Channel to the Big Island. The seas will be approaching the advisory level of 10ft on Friday due to a combination of the long-lasting north-northwest swell mentioned above and the seas associated with the voyages.

Fire weather

A dry air mass in combination with the gusty trade winds and dry fuels will lead to critical fire weather conditions today. As a result, the lee areas of most of the islands will have a red flag warning until 6:00 p.m. tonight.

HFO watches / warnings / notices

Red flag warning until 6:00 p.m. HST tonight for Kauai Leeward, Oahu South Shore, Waianae Coast, Oahu North Shore, Olomana, Central Oahu, Waianae Mountains, Molokai Leeward, Lanai Makai, Lanai Mauka, Maui Leeward West, Maui Central Valley, Leeward Haleakala, Kona, South Big Island, Kohala.
Small Craft Advisory until 6:00 p.m. HST tonight for Kaiwi Channel, Maui County Windward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.

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Data courtesy of NOAA.gov

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