The long-lived High Surf Advisory along our east and northeast facing shores will remain in effect through at least 6pm Wednesday due to overhead rough windswell. A Wind Advisory has also been issued for Maui County due to strong and gusty winds out of the northeast at 30-45 mph with gusts possibly up to 55 mph in some areas. A small new northwest swell filled in yesterday and will continue today, but it won’t amount to much. Still, there could be some fun sets mixed in with the windswell at overhead levels if you know where to go. This pattern will continue through the next couple of days. A larger northwest swell is expected to arrive overnight Wednesday into Thursday with the potential to raise the advisory flags. The strong winds will conspire to rip the tops off of this surf, but we should be used to that by now. Don’t be surprised if we have to wait until Thursday to see any of this action though. The source of this new swell is still active currently approaching the dateline while tracking along the Aleutian Islands. This was a strong system but it wasn’t aimed directly toward Hawai`i which will greatly limit its potential. High pressure north of the islands will continue to provide us with good windswell but it will also prevent any lows from taking aim in our direction as well. A gale that set up well southeast of New Zealand last week aimed a small to moderate south swell toward our summer shores, likely arriving Saturday. Nothing to get excited about, but it could be fun.
East and northeast facing shores should still see windswell around 5-8+ foot. North and northwest facing shores have a series of very small northwest swells passing through combined with wrapping windswell to around 4-7 foot, smaller the closer to town you get. Upper West shores probably won’t see much at maybe 2-4 foot. South facing shores won’t see much either at only 0-3 foot.
Wind and Tide InformationHigh tide at Kahului was 2.33 foot at 2:56 AM late last night, dropping to a low of 0.08 foot at 9:13 AM this morning, then rising to a high of 1.84 foot at 3:04 PM early this afternoon, before once again dropping to a low of -0.01 foot at 9:01 PM late this evening. The sunrise was at 06:46 am this morning and will set at 06:30 pm this evening. The Moon is in a waning gibbous phase and will reach Last Quarter next Monday.
Strong northeast to east-northeasterly tradewinds will be in the 20-30 mph range in most areas today but some areas could see much stronger winds, potentially gusting to 50+ mph. This pattern will likely hold through the rest of the week and into the weekend, but a slow-down is possibly next week.
Weather Outlook for Tuesday
Windy weather is in store this week with limited rainfall focused over windward areas. Strong trades will push some brief showers over leeward locations of the smaller islands. Rainfall will increase a notch Friday night and over the weekend.
Moderate trade wind showers will continue through tonight over windward areas. Some showers will reach leeward locations of the smaller islands as gusty trade winds push the moisture over the terrain. By Tuesday, the lower atmosphere will dry considerably as trade winds push drier than normal air over the aloha state. Satellite derived precipitable water estimates show PW values dropping by 0.25 inches upstream of the state from the current value of 1.1 inches. Even with limited moisture, windward areas will still see some shower activity through the week.
The drying trend will be aided by an upper ridge bringing a stable atmosphere in from the west. The daytime upper air sounding from Lihue shows a temperature inversion building at 5 thousand feet with dry air dominating above the inversion. The Hilo sounding showed moisture up to 13 thousand feet with dry air above. Expect the stable dry air to move east tonight, and by Tuesday the stable atmosphere will blanket the state.
Wind speeds will increase as the atmosphere continues to stabilize. The ridge will provide sinking motion aloft which in turn will enhance the strong inversion over the state and remain through the week. The inversion will squeeze the boundary layer and accelerate winds through the island terrain. Gale force winds are expected over the windier coastal waters Tuesday and Wednesday, and a wind advisory will begin Tuesday morning for the windier areas of the Big Island and Maui county.
At the Big Island summits, the winds are expected to strengthen Tuesday as the pressure gradient aloft tightens between a mid-level low exiting eastward, and a mid-level high wandering in from the west. Guidance agrees with a strong pressure gradient forming Tuesday, and the high wind watch currently in place will likely be upgraded to a warning early Tuesday morning.
Some instability could return over the weekend as an upper trough tries to dig over the islands from the north. Moisture levels remain low, so only a modest increase in showers is expected.
Central Valley (Kahului, Spreckelsville):
WIND ADVISORY IN EFFECT FROM 6 AM TUESDAY TO 6 PM HST WEDNESDAY. Mostly clear with isolated showers. Windy. Lows around 64. Northeast winds 20 to 30 mph. Chance of rain 20 percent.
Leeward West (Lahaina, Ka`anapali):
Sunny with isolated showers. Windy. Highs 74 to 79. Northeast winds 20 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 WEDNESDAY. Mostly cloudy with showers likely. Windy. Lows 55 to 68. 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 WEDNESDAY. Mostly cloudy with showers likely. Breezy. Lows around 65 at the shore to around 49 at 5000 feet. East winds 15 to 25 mph. Chance of rain 70 percent.
Leeward Haleakala (Kihei, Wailea, Makena):
Sunny, breezy. Highs around 77 at the shore to around 61 at 5000 feet. East winds 15 to 25 mph with gusts to 45 mph.
WIND ADVISORY IN EFFECT FROM 6 AM TUESDAY TO 6 PM HST WEDNESDAY. Mostly clear with isolated showers. Windy. Lows around 42 at 7000 feet to around 36 at the summit. East winds around 30 mph. Chance of rain 20 percent.