Hawaii County climate forecast is Might 18, 2021

Hilo

Today: single showers. Partly sunny with a high near 83. Light and changeable winds blowing 5 to 10 miles per hour from east-northeast. The probability of precipitation is 20%.

Tonight: Showers likely, mostly after midnight. Mostly cloudy, with a low of about 66. After midnight a calm wind blows from the east at about 10 km / h. The probability of precipitation is 70%. New rainfall levels of less than a tenth of an inch possible.

Wednesday: Showers likely, mostly before noon. Partly sunny, with a high near 82. East winds 5 to 8 mph. The probability of rainfall is 70%. New rainfall levels of less than a tenth of an inch possible.

Kona

Today: Mostly sunny, with a high near 78. Light and changeable wind blowing from west-southwest 5 to 9 miles per hour.

Tonight: A few showers, mostly before midnight. Mostly cloudy, with a minimum value of around 65. Light and changeable wind, blowing at around 10 km / h from the north-northwest. The probability of precipitation is 40%. New rainfall levels of less than a tenth of an inch possible.

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Wednesday: A few showers after noon. Partly sunny, with a peak near 79. Light and changeable wind from the northwest with 5 to 11 km / h. The probability of precipitation is 30%. New rainfall levels of less than a tenth of an inch possible.

Waimea

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Today: single showers. Mostly sunny, with a high near 73. Windy, with northeasterly winds of 21 to 24 mph, with gusts of up to 54 mph. The probability of precipitation is 20%.

Tonight: A few showers, mostly after 1am. Mostly cloudy, with a low of around 56. East winds around 23 km / h, with gusts of up to 30 km / h. The probability of precipitation is 40%. New rainfall levels of less than a tenth of an inch possible.

Wednesday: A few showers. Mostly sunny, with a peak near 72. East-northeast winds 11 to 23 km / h, with gusts of up to 32 km / h. The probability of precipitation is 40%. New levels of precipitation between a tenth and a quarter of an inch are possible.

Kohala

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Today: single showers. Partly sunny, with a peak near 67. Windy, with easterly winds of 20 to 40 km / h, with gusts of up to 60 km / h. The probability of precipitation is 20%.

Tonight: Showers likely, mostly after midnight. Mostly cloudy, with a minimum of about 54. Breeze, with an easterly wind of 16 to 32 km / h, with gusts of up to 45 km / h. The probability of precipitation is 70%. New rainfall levels of less than a tenth of an inch possible.

Wednesday: Showers likely, mostly before noon. Partly sunny, peaking near 66th breezes, with an easterly wind of 11 to 25 miles per hour, with gusts of up to 35 miles per hour. The probability of precipitation is 70%. New rainfall levels of less than a tenth of an inch possible.

Southern big island

Today: A few showers after noon. Mostly sunny, with a high near 79. Windy, with an easterly wind of 22-25 mph, with gusts of up to 32 mph. The probability of precipitation is 20%.

Tonight: A few showers before midnight. Partly cloudy, with a low of 72. Windy, with an east-northeast wind of 21 to 23 mph, with gusts of up to 45 mph. The probability of precipitation is 20%.

Wednesday: A few showers after noon. Mostly sunny, with a peak near 79. Windy, with easterly winds of 21 to 23 mph, with gusts of up to 48 km / h. The probability of precipitation is 20%.

Feedback

Today: single showers. Mostly sunny, peaking near 80. West-northwest winds 8 to 24 miles per hour turning east-northeast in the afternoon. Gusts of wind can reach up to 18 miles per hour. The probability of precipitation is 20%.

Tonight: Showers likely, mostly after midnight. Mostly cloudy, with a low of about 63. North-northeast winds 8 to 11 mph. The probability of precipitation is 70%. New levels of precipitation between a tenth and a quarter of an inch are possible.

Wednesday: Showers likely, mostly before noon. Partly sunny, with a high near 79. Northeasterly winds 10 to 21 mph. The probability of precipitation is 70%. New levels of precipitation between a tenth and a quarter of an inch are possible.

Waikoloa

Today: Mostly sunny, with a peak near the 81st breeze, with an east-northeast wind of 17 to 35 km / h, which decreases to 5 to 16 km / h in the afternoon. Winds can blow up to 31 miles per hour.

Tonight: A few showers before midnight. Partly cloudy, with a low of about 66. East winds about 10 km / h. The probability of precipitation is 20%.

Wednesday: A few showers after noon. Mostly sunny, with a peak near 82. North wind around 10 km / h. The probability of precipitation is 20%.

Summary

The trade winds will continue for the remainder of the week, although a slight weakening is expected today and over the weekend. Rain showers favor windward and mountainous areas with short rainfall compared to leeward locations. This weekend, wetter conditions and an increase in rainfall are possible.

discussion

The breezy trade winds will ease slightly today as a wide surface of 1029 mb drifts to the east far northeast of the islands. Trades can also weaken further at the weekend. According to the GFS, the mid-level ridge will maintain a stable air mass over the islands through Friday, with an inversion at approximately 8k feet. Rainwater will float from just under an inch to a height of 1.20 by Friday. With this in mind, we expect a typical trade wind pattern with showers that favor the windward and mountainous areas, especially the nights and mornings. There will be a day or two when it gets a little rainier and or a day or two when it won’t be as rainy. But there will be plenty of sunshine along the leeward beaches.
After Friday, the GFS and ECMWF models disagree on certain points. To cut a long story short, the JRC has a mid-low southwest of the Big Island on Saturday, where the circulation brings deep tropical humidity of less than 45,000 feet over the islands from the east and south-east as of Saturday night. The ECMWF, on the other hand, has a middle to upper valley floor over the eastern part of the island chain during the weekend. This stationary trough holds the deep tropical moisture east of the Big Island. A slight influence is expected thermodynamically with the cold air pocket with the mean low / low, where only minus 9 or minus 10 degrees C are determined. However, should the JRC fail, a thunderstorm may break into the high-lying terrain of the Big Island on Sunday afternoon, along with a few spotty, heavy trade wind showers. The surface wind field differs between the GFS and the EC over the weekend where the GFS has a surface trough over the islands between Saturday night and Sunday night. This trough will lighten the wind field and produce a hybrid mix of light easterly winds and a pattern of ocean breezes during the day and land breezes at night, particularly on the windswept islands of Maui and the Big Island. Should the EC solution succeed, the trade winds on the islands will continue and expand, although the trade winds could be slightly lighter in the moderate range due to a front northwest of Kauai.
Current satellite and radar show a scattered field of cumulus clouds and embedded showers. This field is concentrated from Oahu to the east. Windward Kauai is going to see a few showers this morning, and that’s about it. It is mostly dry against the wind. Overall, the windward and mountainous areas of the larger islands will absorb most of these trade showers. As the day progresses, some of these clouds and showers will dissipate under a strong and stable mass of air, resulting in plenty of sunshine, especially on the south and west facing beaches. We expect the lee side of the Big Island to see more clouds this afternoon and evening.

aviation

High pressure northeast of the area will hold moderate to locally strong trade winds over the islands and adjacent waters until tonight. VFR conditions will prevail, with short periods of MVFR conditions over windward slopes possible as low clouds and SHRA pass by.
AIRMET Tango will remain in effect during moderate turbulence from south to west of the mountains and will likely continue until tonight.

marine

High pressure northeast of the islands, relative to lower pressure south of the state, maintains moderate to locally strong trade winds. In general, these moderate to fresh trades will last for most of the week. For today and this weekend there is potential for a slight weakening of the winds, the latter referring to an approaching frontal border to the north. A Small Craft Advisory (SCA) is in effect until this afternoon for select coastal waters around the islands of Oahu, Maui and Hawaii, largely due to the acceleration of the northeast around these islands. The Oahu zones are expected to shut down at 6:00 p.m. HST tonight, leaving a Tuesday evening and Wednesday SCA for the normally windier southern waters of Maui County and the Big Island through Wednesday afternoon. An extension of this SCA is likely.
A little higher surf is expected along the north and west coasts until Wednesday, as some small north-west swells move around the islands in the late season. Today’s swell is more north-westerly and will have maximum surf below normal height. A secondary, further west-northwest, small swell is coming into Wednesday tonight. This swell sustains the northbound surf, but it can also be just north enough to avoid shadowing the upstream islands and create a small bump to the westerly coastal surf of Kauai and Oahu on Wednesday. Several days of intensive trading have created fully developed seas. As a result, conditions will be choppy along the east-facing coastlines throughout the week. The south-facing bank surf will remain small for the next few days or be slightly below seasonal norms. In the long run, a slightly larger, long-period pulse could arrive from the southern hemisphere early next week. These waves can raise the surf on the south coast to almost typical summer heights at the end of May.

HFO clocks / warnings / notices Ad

Small Craft Advisory until Wednesday 6:00 p.m. HST for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6:00 p.m. HST tonight for Oahu Leeward Waters, Kaiwi Channel, Maui County Windward Waters, Maui County Leeward Waters.

Data courtesy of NOAA.gov

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