The National Weather Service has issued a High surf Advisory for Maui’s east facing shores effective through 6pm Monday evening due to a building short-period windswell. The current northwest swell should still offer plenty head-high surf along our north and northwest facing shores, slowly dropping through Monday and possibly into Tuesday. Another northwest swell should arrive around Wednesday. A Wind Advisory is also in effect as northeasterly winds howl in the 25-35 mph range, potentially gusting to 45 mph in some areas. This will, of course, blow out the surf at most breaks, so don’t expect much out there. The current swell is on the way down, originating from a low near the Kuril Islands that aimed a strong gale and associated fetch in our direction over several days as the low tracked toward the east. This low occluded briefly, allowing a nice long fetch to take aim toward Hawai`i. Another low developed over the Kuril Islands Friday, and it is currently tracking toward the east to east-northeast. The resulting swell won’t be as good as the current fading swell, but we should still be able to pull in a decent upper-end small to moderate swell arriving late Wednesday into Thursday. The models are suggesting a slow-down in surf production through the rest of the forecast period, so get it while it’s here. A combination of a low northeast of the islands and strong high pressure far north-northeast of the state is responsible of the rising windswell, expected to peak Monday and then slowly dropping into the middle of the week.There are no ground swells along our south facing shores nor will there be anything better than weak thigh-high background swell through the forecast period.
North and northwest facing shores should still have surf in the 4-6 foot range, mixed with wrapping windswell, potentially rising to well overhead levels in some areas. Upper West shores won’t have as much action at 1-3 foot, but select breaks may see a few larger sets. Windswell along the east and northeast facing shores should rise to 5-8 foot. South facing shores have nothing more than tiny background swell at 0-2 foot.
Wind and Tide Information
High tide at Kahului was 1.8 foot at 2:14 AM late last night, dropping to a low of -0.1 foot at 8:31 AM this morning, then rising to a high of 2.0 foot at 2:57 PM early this afternoon, before once again dropping to a low of 0.3 foot at 8:57 PM early this evening
The sunrise was at 06:06 am this morning and will set at 06:45 pm this evening. The Moon is currently 13 days old, and is in a Full Moon phase. The next Waning Gibbous will occur at 7:53 AM on Tuesday, April 22nd.
The northeast to east-northeasterly tradewinds have strengthened to strong levels of 20-30 mph. The winds are expected to peak later today and should begin to slowly drop over the next few days to stabilize at moderate to breezy levels over the second half of the week.
Sunset: 6:45 PM
Weather Outlook for Sunday
Increasing trade winds are due to a strong high pressure system passing north of the state. Clouds and showers will favor windward and mauka areas with the trade winds sufficiently strong enough to blow some showers over to leeward areas at times. Drier and less breezy weather is expected for the second half of the week as the high moves away from the islands and starts to weaken.
Winds continued above advisory levels for Lanai overnight, with portions of the Kohala area on the Big Island above from time to time. Backed by an ascat pass around 9 pm showing strong winds over the water, a wind advisory continues for Lanai, Kahoolawe and the Kohala area of the Big Island. Winds are on the increase near South Point, so have added that region to the wind advisory this morning.
Winds over some of the higher portions of Oahu are approaching advisory levels, but have left them out of the advisory at this time. Will be monitoring the situation as the day wears on.
The increase in trade winds is due to a high pressure system passing to the north of the main Hawaiian islands. This high will be the driving force for our weather for much of the week. The models are in good agreement with the strengthening through Monday as it edges to the northeast. Beyond Monday, the high lifts to the northeast and starts a slow weakening trend. The combination of a weakening system and moving away from the islands should result in a decline in winds Monday night and Tuesday.
Showers persisted over mainly windward areas of Maui county and the Big Island overnight. The Puu Kukui gage on Maui received by far the most rainfall with 2.49 inches between 8 pm and 2 am. Under an inch was received at the remaining gages on Maui county and the Big Island. The mimic total precipitable water /pw/ showed an increase in moisture in this area overnight, and the current mimic data continues to show elevated PW upstream of these areas. As such, expect showers to continue over the next couple of hours, but then start to taper off this afternoon.
An upper level trough digging down from the northwest has helped to enhance the showers mentioned above. The trough is expected to set up to the southeast of the islands tomorrow, and develop an upper level low near 26°N 145°W Monday night. This system will likely continue to enhance shower activity into the middle of the week.
By the middle of the week, the high pressure system will be moving further from the islands, allowing trades to settle down some, so expect the second half of the upcoming week to be less windy and drier.
Central Valley (Kahului, Spreckelsville):
Mostly clear with isolated showers. Breezy. Lows 63 to 69. Northeast winds 15 to 25 mph with gusts to 45 mph. Chance of rain 20 percent.
Leeward West (Lahaina, Ka`anapali):
Partly cloudy with isolated showers. Windy. Lows 62 to 71. Northeast winds 25 to 30 mph with gusts to 45 mph. Chance of rain 20 percent.
Windward West (Wailuku, Waiehu):
HIGH SURF ADVISORY IN EFFECT UNTIL 6 PM HST MONDAY. Partly sunny. Showers likely in the morning, then scattered showers in the afternoon. Windy. Highs 68 to 80. Northeast winds 15 to 30 mph. Chance of rain 70 percent.
Windard Haleakala (Hana, Haiku, Makawao):
HIGH SURF ADVISORY IN EFFECT UNTIL 6 PM HST MONDAY. Mostly cloudy. Occasional showers in the morning, then showers likely in the afternoon. Breezy. Highs around 79 at the shore to around 64 at 5000 feet. East winds 10 to 25 mph with gusts to 40 mph. Chance of rain 90 percent.
Leeward Haleakala (Kihei, Wailea, Makena):
Mostly clear. Lows around 67 at the shore to around 52 at 5000 feet. East winds 10 to 20 mph with gusts to 40 mph.
Mostly clear with isolated showers. Windy. Lows around 46 at 7000 feet to around 40 at the summit. East winds around 35 mph with gusts to 55 mph. Chance of rain 20 percent.
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