Hawaii County climate forecast is March 31, 2021

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Photo credit: James Grenz

Hilo

Today: isolated showers, thunderstorms also possible after noon. Partly sunny, with a high of nearly 77. Calm wind blowing northeast 5 to 7 miles per hour in the afternoon. The risk of precipitation is 50%. New rainfall less than a tenth of an inch, except during thunderstorms greater amounts.

Tonight: Occasional showers. Low around 64. East-northeast winds 5 to 8 miles per hour, calming in the evening. The risk of precipitation is 80%. New rainfall levels of less than a tenth of an inch are possible.

Thursday: Showers likely, mostly before noon. Partly sunny, with a high of nearly 77. Light and changing winds blowing northeast 5 to 9 miles per hour in the afternoon. The risk of precipitation is 70%. New rainfall levels of less than a tenth of an inch are possible.

Kona

Today: isolated showers and thunderstorms after noon. Partly sunny, with a high of nearly 80. Light and changing winds blowing 5 to 8 miles per hour west in the afternoon. The probability of precipitation is 30%. New rainfall less than a tenth of an inch, except during thunderstorms greater amounts.

Tonight: a few showers, mostly before midnight. Partly cloudy with a low of around 62. Northwest winds 5 to 7 miles per hour, calming after midnight. The risk of precipitation is 40%. New rainfall levels of less than a tenth of an inch are possible.

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Thursday: a few showers after noon. Mostly sunny, with a high of almost 79. Southwest winds 6-11 miles per hour that become light and changeable in the afternoon. The probability of precipitation is 30%. New rainfall levels of less than a tenth of an inch are possible.

Waimea

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Today: isolated showers, thunderstorms also possible after noon. Partly sunny, with a high of nearly 75. Breezy, with northeasterly winds of 5 to 10 mph, rising to 12 to 17 mph in the afternoon. Winds could gust up to 24 miles per hour. The risk of precipitation is 50%. New rainfall is between a tenth and a quarter of an inch, with the exception of higher amounts that are possible during thunderstorms.

Tonight: a few showers. Mostly cloudy, with a minimum of 53. Breezy, with northeasterly winds of 16 to 18 mph, with gusts of up to 25 mph. The risk of precipitation is 50%. New levels of rainfall between a tenth and a quarter of an inch are possible.

Thursday: a few showers. Partly sunny, with an altitude of nearly 74. Breezy, with northeasterly winds of 13 to 18 miles per hour, with gusts of up to 25 miles per hour. The risk of precipitation is 40%. New levels of rainfall between a tenth and a quarter of an inch are possible.

Kohala

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Today: isolated showers, thunderstorms also possible after noon. Partly sunny, with a high of almost 71. Windy, with east-southeast winds of 5 to 10 mph, turning 18 to 23 mph in the morning from east to northeast. Winds could gust up to 32 miles per hour. The risk of precipitation is 50%. New rainfall less than a tenth of an inch, except that higher amounts are possible during thunderstorms.

Tonight: Occasional showers. Low around 46. Windy, with an east-northeast wind of 22-25 mph, with gusts of up to 36 mph. The risk of precipitation is 80%. New rainfall levels of less than a tenth of an inch are possible.

Thursday: Showers likely. Partly sunny, with an altitude of nearly 70. Breezy, with east-northeast winds of 15 to 22 mph, with gusts of up to 31 mph. The risk of precipitation is 70%. New rainfall levels of less than a tenth of an inch are possible.

South Big Island

Today: isolated showers, thunderstorms also possible after noon. Mostly sunny, with an altitude of almost 80. Windy, with an easterly wind of 20 to 23 miles per hour, with gusts of up to 30 miles per hour. The probability of precipitation is 20%.

Tonight: isolated showers. Partly cloudy with a low of around 70. Windy, with east-northeast winds of 21-25 mph, with gusts of up to 32 mph. The probability of precipitation is 20%.

Thursday: isolated showers. Mostly sunny, with an altitude of nearly 79. Windy, with easterly winds of 21 to 23 miles per hour, with gusts of up to 30 miles per hour. The probability of precipitation is 20%.

Feedback

Today: isolated showers, thunderstorms also possible after noon. Partly sunny with a high of nearly 76. West winds 5 to 10 miles per hour blowing northeast in the afternoon. The risk of precipitation is 50%. New rainfall is between a tenth and a quarter of an inch, with the exception of higher amounts that are possible during thunderstorms.

Tonight: Occasional showers. Low around 62. North-northeast winds 6 to 10 miles per hour. The risk of precipitation is 80%. New levels of rainfall between a tenth and a quarter of an inch are possible.

Thursday: Showers likely, mostly before noon. Partly sunny with a high near 76. North-northeast winds 8 to 13 miles per hour. The risk of precipitation is 70%. New levels of rainfall between a tenth and a quarter of an inch are possible.

Waikoloa

Today: 20 percent chance of showers and thunderstorms after noon. Mostly sunny, with a high of nearly 81. Breezy, with east-southeast winds of 7 to 16 miles per hour going north in the morning. Winds could gust up to 22 miles per hour.

Tonight: isolated showers before midnight. Partly cloudy, with a low of around 62. Airy, with a northeast wind around 16 mph, with gusts as high as 22 mph. The probability of precipitation is 20%.

Thursday: a few showers after noon. Mostly sunny, with a high of nearly 80. Breezy, with a northeast wind of 13 to 18 mph that drops to 7 to 12 mph in the afternoon. Winds could gust up to 25 miles per hour. The probability of precipitation is 20%.

Summary

A typical trade wind pattern will persist across the island chain for the next 7 days. Moderate trade winds are expected until Friday, with trades rising to windy levels over the weekend and becoming windy early next week. Passing showers favor wind and mauka areas during the period, especially at night and early in the morning, with a stray shower spreading downwind from time to time. Masses could get more active Sunday through Monday as some old frontal remains move through the island chain.

discussion

Currently, at the surface, an elevation of 1046 mb is centered about 2000 miles north-northwest of Honolulu, while another elevation of 1030 mb is centered about 2200 miles northeast of the state. Between these two heights there is a low pressure trough which effectively limits the trade wind reaction to the high heights. As a result, moderate trade winds prevail throughout the island chain this morning. Infrared satellite imagery shows a mix of high and low clouds, resulting in partially cloudy conditions in most areas, with some pockets of larger cloud cover in windward areas. Radar images show scattered showers moving to windward areas, with a decaying shower, or a few sprinkles that get to leeward areas from time to time. The main short term concern revolves around the potential for thunder on the Big Island this afternoon.
Model solutions show that a short-wave trough runs across the Big Island this afternoon. Combined with a mid-level rise in humidity and persistent instability, a thunderstorm or two cannot be ruled out. As a result, there will be a slight probability of thunderstorms over the Big Island this afternoon. Otherwise there will be quite typical trade wind weather throughout the country in the forecast period. Passing showers favor wind and mauka areas, especially at night and early in the morning, with a stray shower spreading leeward from time to time. Masses could get more active Sunday through Monday as some old frontal remains move through the island chain.
Trades are expected to remain at moderate levels through Friday with only minor fluctuations in strength. A new strong high north of the state will gradually become more dominant over the weekend as it builds up to the south and closer to the island chain. This is expected to take weekend trades to airy levels, with even windier conditions possible early next week.

aviation

Moderate to locally strong trade winds will develop today as high pressure builds up far north of the area. AIRMET TANGO for tempo-wise turbulence at a low level above and immediately in front of the wind of the terrain of all islands is effective at 20Z.
Trade winds carry passing showers along exposed eastern slopes and coasts, resulting in short periods of visibility and coverage of the MVFR. The Big Island and Maui have the highest chances when the offshore moisture gets into this area. A slight probability of thunderstorms is forecast for the Big Island this afternoon. There are currently no AIRMETs in effect for mountain cover as there are areas of low coverage this morning. However, they could be on display later today when the cloud cover fills in a little more.
Only a few to scattered high clouds along the subtropical jet will move over the islands today.

marine

Fresh to strong trade winds from northeast to east will persist throughout the weekend as high pressure builds up in the north. The Small Craft Advisory has been expanded to cover the typically windier waters around Maui County and the Big Island and may need to be expanded to other areas over the weekend.
Surfing along the south-facing coast will be just below the advisory level today and then slowly relax until Friday tonight when the south wind picks up. Over the weekend, a mix of southern background swell and brief southeast energy should be enough to keep the surf from flattening along southern exposures.
Surfing along the north and west facing coast will be trendy today when a small, northwest swell hits and builds up along the chain of islands. This source should last through Friday and then through the weekend. The guide shows a decent gradient that forms over a large area north of the islands between 1035 mb high and low pressure over the northeast Pacific on weekends. Strong to nearly stormy northeast winds concentrated on the islands within the 020-040 directional bands will be sufficient to produce a decent north-northeast swell for north-facing exposures up to or early next week.
Trade winds will keep the surf stable on the east-facing banks until Friday. Surfing along the east-facing coast will spike over the weekend through early next week due to a combination of strong local eastern trades and the north-northeast surge mentioned above. Highs could hit an advisory level early next week if this scenario occurs.

HFO watches / warnings / notices

Small Craft Advisory until 6 a.m. HST Thursday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, and Big Island Southeast Waters.

Data courtesy of NOAA.gov

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