We should still see plenty chest-high to overhead surf this morning but it has peaked and is on the way down. Our next chance for anything decent won’t arrive until the weekend, so be sure to get it while it’s here. Very small south to southwesterly background swell won’t offer anything rideable along our south shores. A developing low just southeast of Kamchatka will continue to build over the next couple of days while tracking roughly east along the Aleutian Islands. At this time it looks like it will peak Wednesday just before crossing the dateline, but it should fade into the weekend while sending plenty swell in our direction. The resulting northwest swell should arrive Saturday near or exceeding advisory levels. A minor low currently near the central Aleutian Islands may precede this swell by about a day, possibly offering a small north-northwest swell arriving Friday. A deep low is developing south to southeast of New Zealand, close to the Ross Ice Shelf, that has the potential to send some enhanced background swell in our direction. Most of this energy will be well outside of our swell window but the low is modeled to veer toward Central America around mid-week. It still won’t be aimed well in our direction but the odds for us receiving an edge-pass due to angular spreading should be higher. If we’re lucky, we could see this energy reaching our shores around next Monday or Tuesday, but don’t expect it. The South Pacific will be rather active through the forecast period, but not much, if anything, will be sent in our direction aside from background swell.
North and northwest facing shore should be around 5-8 foot still this morning but will slowly fade through the day. Upper West shores won’t see much action at only 0-3 foot but some of the better breaks could pick up higher sets if you know where to go. Weak windswell and wrapping northwest surf may offer small surf along the east and northeast facing shores around 1-4 foot. South facing shores may see tiny background swell around 0-3 foot, probably not rideable.
Wind and Tide InformationHigh tide at Kahului was 2.08 foot at 1:50 AM late last night, dropping to a low of -0.12 foot at 8:05 AM this morning, then rising to a high of 2.05 foot at 2:18 PM early this afternoon, before once again dropping to a low of 0.1 foot at 8:19 PM early this evening. The sunrise was at 06:21 am this morning and will set at 06:40 pm this evening. The Moon has reached Full Moon phase and will now begin to wane gibbous until reaching Last Quarter next Tuesday.
The easterly winds will remain light to moderate around 10-15 mph today, likely swinging to a more northeasterly direction early this afternoon while increasing slightly. An increasing trend is expected over the next few days.
Weather Outlook for Tuesday
A moist and unstable air mass will remain in place over the islands for the next couple of days. A disturbance aloft passing over the islands Tuesday night through Wednesday is forecast to enhance moisture near Kaua`i and O`ahu, bringing the threat of heavy rain and flash flooding. The departure of the disturbance will bring quieter weather late Thursday and Friday, but unsettled weather is possible again next weekend.
Moisture associated with a weak surface trough near Kaua`i and O`ahu continues to focus showers and low cloud cover across the main island chain. Middle and high clouds along the eastern flank of an upper trough west of the islands continue to push northeastward across the area this evening. Afternoon soundings show our airmass is unstable, with k-index values above 20 and lifted index values between minus 0.5 and minus 3.5. In short, we have a moist unstable airmass and a lingering surface trough available to act as a low level convective trigger.
Latest guidance indicates that the passage of a pair of short wave troughs aloft will bring the threat of stormy weather as they further destabilize our pre-existing moist and unstable airmass. The first trough passage is expected from late Tuesday into Thursday, with the second expected over the weekend. Low level winds will generally be light to moderate trade winds, becoming stronger northerlies this weekend.
In spite of growing confidence in a stormy scenario this week, it remains unclear exactly how events will unfold. Clouds and showers will likely favor windward areas tonight and Tuesday morning, with light trade winds allowing afternoon clouds and showers to develop leeward in response to sea breeze convergence on Tuesday. Some of these showers could be briefly heavy. The passage of a short wave upper trough Tuesday night and Wednesday will likely bring a period of heavy rain and possibly thunderstorms. The greatest threat, at least initially, will be over Kaua`i and O`ahu and a flash flood watch is in effect for these islands. If thunderstorms develop, forecast vertical wind profiles indicate sufficient shear to support organized strong thunderstorms, potentially even severe, mainly near Kaua`i and O`ahu.
The passing short wave will also sharpen the surface trough, with northeast winds expected to increase near Kaua`i in response. As the upper trough slides down the island chain, it will pass over drier air and weaken as it goes. However, it may still trigger enhanced trade wind showers across Maui county and the Big Island Thursday. The trough is then forecast to continue weakening and move east, with weak ridging following close behind on Friday.
A second short wave trough is forecast to dig toward the islands from the northwest on Saturday. This feature may have less moisture with which to work, but could still be a significant weather maker as it swings through Saturday and Sunday. Forecast confidence remains low but this trough should support the passage of a surface front, with moderate to strong north winds spreading down the chain after the front passes, and then persisting into next week.
Although winds over the higher elevations of the Big Island have subsided and the high wind warning has been cancelled, the passage of the troughs aloft will likely bring periods of strong winds to the Big Island summits, with the first chance being from late Wednesday through Friday afternoon, and the second beginning Saturday night.
Central Valley (Kahului, Spreckelsville):
Mostly cloudy with isolated showers. Highs around 80. South winds around 10 mph shifting to the north in the late morning and afternoon. Chance of rain 20 percent.
Leeward West (Lahaina, Ka`anapali):
Mostly cloudy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 76 to 81. East winds 10 to 15 mph. Chance of rain 40 percent.
Windward West (Wailuku, Waiehu):
Mostly cloudy with scattered showers. Highs 65 to 78. Northeast winds 10 to 15 mph. Chance of rain 50 percent.
Windard Haleakala (Hana, Haiku, Makawao):
Mostly cloudy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 77 at the shore to around 61 at 5000 feet. South winds around 10 mph shifting to the east in the late morning and afternoon. Chance of rain 50 percent.
Leeward Haleakala (Kihei, Wailea, Makena):
Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 80 at the shore to around 65 at 5000 feet. Light winds becoming northeast 10 to 15 mph in the late morning and afternoon. Chance of rain 40 percent.
Mostly cloudy with isolated showers. Highs around 61 at 7000 feet to around 56 at the summit. Light winds becoming northeast around 10 mph in the late morning and afternoon. Chance of rain 20 percent.