Hawaii County Weather Forecast for July 18, 2024
Hilo
Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 78 to 87 near the shore to 66 to 71 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.
Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 63 to 71 near the shore to 54 to 59 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.
Friday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 79 to 87 near the shore to around 70 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.
Kona
Today: Mostly sunny with isolated showers. Highs 82 to 89 near the shore to around 67 near 5000 feet. Light winds. Chance of rain 20 percent.
Tonight: Partly cloudy with isolated showers. Lows around 73 near the shore to 49 to 54 near 5000 feet. Light winds. Chance of rain 20 percent.
Friday: Mostly sunny with isolated showers. Highs 82 to 90 near the shore to around 68 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.
Waimea
Today: Mostly sunny with isolated showers. Highs around 80 near the shore to 67 to 79 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.
Tonight: Partly cloudy with isolated showers. Lows 63 to 71 near the shore to 54 to 62 near 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.
Friday: Mostly sunny with isolated showers. Highs 65 to 85. East winds up to 15 mph. Chance of rain 20 percent.
Kohala
Today: Mostly sunny with isolated showers. Highs around 80 near the shore to 67 to 79 near 3000 feet. East winds up to 15 mph. Chance of rain 20 percent.
Tonight: Partly cloudy with isolated showers. Lows 63 to 71 near the shore to 54 to 62 near 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.
Friday: Mostly sunny with isolated showers. Highs 65 to 85. East winds up to 15 mph. Chance of rain 20 percent.
South Big Island
Today: Mostly sunny. Highs around 85 near the shore to around 67 near 5000 feet. East winds up to 15 mph.
Tonight: Partly cloudy. Lows around 74 near the shore to around 53 near 5000 feet. Northeast winds up to 10 mph.
Friday: Mostly sunny. Highs around 86 near the shore to around 69 near 5000 feet. East winds up to 15 mph.
Puna
Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 78 to 87 near the shore to 66 to 71 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.
Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 63 to 71 near the shore to 54 to 59 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 50 percent.
Friday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 79 to 87 near the shore to around 70 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.
Waikoloa
Today: Sunny. Highs 83 to 89 near the shore to 65 to 72 above 4000 feet. North winds up to 15 mph.
Tonight: Mostly clear. Lows around 73 near the shore to 50 to 56 above 4000 feet. East winds up to 15 mph.
Friday: Sunny. Highs 84 to 90 near the shore to 65 to 73 above 4000 feet. North winds up to 10 mph.
Detailed Forecast
Synopsis
Moderate trades will continue over the next few days with breezy trades returning early next week. Dry and stable air over the state should limit windward showers over most islands into Friday. Isolated afternoon showers may develop with the sea breezes over the lower slopes of leeward Big Island. A weak disturbance riding in on the trade winds from the east will increase clouds and shower activity from Friday night into Sunday. Another weak disturbance will move into the Hawaii region by next week Tuesday and Wednesday.
Discussion
Satellite imagery this morning shows a weak trough roughly 400 miles east of Hilo drifting towards the islands on the trade winds. Trade wind temperature inversion heights were measured by upper air soundings this morning at 2 AM HST around 5,000 feet above Mean Sea Level (MSL) at Lihue and around 6,500 feet MSL at Hilo. These low inversion heights indicate fairly strong subsidence (downward moving air) and stable conditions over the western and central islands, which tend to limit vertical cloud growth and reduce shower activity. Brief passing showers will likely continue over the windward Big Island and East Maui as easterly trade winds drive trade wind clouds and moisture up the mountain slopes. Short range global model guidance continues to show this strong subsidence inversion will continue into Friday due to the high pressure ridge over the island chain.
The weather pattern changes slightly from Friday evening into Saturday morning as a weak low level trough moves from east to west down the island chain over the weekend. The low level forcing with this trough and added moisture advection into the islands will push back on the large scale subsidence, raising the temperature inversion to higher heights, allowing for higher cloud tops and increasing shower activity. Windward and mountain areas will see more shower activity than the drier terrain sheltered leeward slopes. The Big Island and Maui may see slight increases to cloud and shower trends with the afternoon leeward sea breezes as wrap around moisture is driven up and convects along the mountain slopes. Statewide drying trends return from Sunday through Monday. Then a slightly stronger low level trough spreads another round of increasing moisture and shower trends from east to west across the islands next week, from Tuesday morning into Wednesday.
Aviation
Moderate to locally breezy trades will continue through the end of the week. SHRA and low cigs will favor windward and mauka areas and could bring brief periods of MVFR. Otherwise, VFR should prevail.
No AIRMETs are currently in effect.
Marine
Moderate trade winds will persist into the weekend as a weak high remains north of the state. Moderate to locally strong trades may return late into the weekend as a weak trough northeast of the state dissipates and the high strengthens north of the state. Small Craft Advisory conditions may return to typically windy areas around Maui County and the Big Island during this time. The high will further develop northeast of the state early next week, strengthening trades across the state.
Near average surf along south facing shores will persist today before easing to below average Friday. Background southerly swells is then expected Friday through the remainder of the forecast period, maintaining below average surf along south facing shores.
Small, choppy surf is expected for east facing shores for the next few days as trades remain in the moderate range locally and upstream. Rough, choppy is expected to gradually return late in the weekend into early next week as strong trades return. No significant swells are expected elsewhere.
Local tide gauges show water levels are gradually rising more and more above model guidance across the state, due to spring tides peaking this weekend during the afternoon high tide cycle. Water levels may reach or exceed the 1 foot Mean Higher High water (MHHW) threshold as early as Friday afternoon, causing minor flooding along low lying coastal zones and prompting the issuance of a Coastal Flood Statement (CFS). The likelihood of water levels exceeding the 1 foot threshold is high around Maui and the Big Island Saturday into Monday, however there is a chance water levels could reach the 1 foot threshold around Oahu and Kauai as well.
HFO Watches/Warnings/Advisories
None.
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Data Courtesy of NOAA.gov