The National Weather Service has issued a High Surf Advisory for our south facing shores. Wave heights should come in at overhead levels at many south shore breaks, potentially coming in at well overhead levels at the best locations. This advisory is in effect through 6pm Friday evening but the surf will continue to slowly drop throughout the weekend. Sloppy small to moderate windswell should also return to our east and northeast facing shores in the waist to chest-high range. The north shore will stay more or less flat aside from some wrapping windswell at tiny to small levels. The area east of New Zealand is active with a long fetch of mediocre winds but it should provide us with plenty more small to low-end moderate south swell in about a week. A building low well east of the northern island of New Zealand should provide a larger bump to this energy over the next several days. It’s still a bit too early for any confidence but the models are showing a favorable southern storm track through the forecast period which should allow even more summer surf to develop. More details as this unfolds. The tropical east North Pacific will continue to churn out strong tropical storms and it looks like another strong hurricane is likely to develop south of Baja California early next week. It does not look like this will have any threat to the islands but perhaps we’ll see a little easterly swell out of it.
Today’s Surf Summary
South facing shores should rise into the 4-7+ foot range today depending on where you paddle out. Some lesser exposed breaks may not offer much while select breaks pull in well overhead sets. Windswell along the east and northeast facing shores should also rise into the 2-4 foot range but it will be sloppy and choppy. North and northwest facing shores won’t have any action to mention at 0-3 foot but some wrapping windswell may allow some tiny to small surf in select areas. Upper West shores will stay flat at 0-2 foot but select breaks may pull in some surf from the south if you know where to look.
Wind and Tide Information
High tide at Kahului was 1.4 foot at 1:18 AM late last night, dropping to a low of 0.1 foot at 7:28 AM this morning, then rising to a high of 2.4 foot at 2:35 PM early this afternoon, before once again dropping to a low of 0.7 foot at 8:58 PM early this evening
The sunrise was at 06:06 am this morning and will set at 06:50 pm this evening. The Moon is currently 27 days old, and is in a Waning Crescent phase. The next New Moon will occur at 2:13 PM on Monday, August 25th.
Moderate northeast to east-northeasterly tradewinds will continue around 19-20 mph today and should remain at similar levels through Saturday before slowly decreasing Sunday into the upcoming week. Wind speeds should stay rather light through much of next week.
Sunset: 6:49 PM
Weather Outlook for Friday
Trade winds will continue with minor changes in speed into next week. Showers generally will be light, and limited to slopes of the Big Island each afternoon, and windward slopes across the state all day. However, showers may be slightly more active from Sunday night into Monday.
Although satellite measurements still detected a bubble of moist air around and west of the smaller islands, a drier air mass with more stable low clouds moved in from the northeast. Subsidence from a mid-level ridge expanding over the state from the northeast also helped to suppress shower development. The stable low clouds may yet produce a few showers when forced up windward slopes, but accumulation should remain on the light side.
Solutions largely agreed that the expansion of the ridge aloft will be brief, and that broad, shallow troughing then will expand over the state from the southwest into the weekend. The resulting reduction in subsidence will tend to counter a decrease in precipitable water upwind, so the practical change in trade showers likely will be, subtle. The shallow trough and weak ridge then will alternate expanding over the state and retreating, resulting in little net effect locally.
From Sunday into Monday, guidance still agreed that a moister air mass may pass over the islands. However, the phase of the alternating weak ridging and weak troughing aloft will determine whether showers can utilize the full potential of this precipitable water. As is typical during trade-wind weather, solutions probably exaggerated the amplitude of these changes.
By around the middle of next week, some models predicted a more longer-lived mid-level trough to develop over the state from east to west, .or from northeast to southwest. This development appeared to be linked in some way with the unusual tropical cyclone activity in the east Pacific, so confidence in this outcome was not high.
Otherwise, guidance predicted the subtropical ridge to the north to remain mostly in place through the forecast period, keeping the trade winds blowing over the islands. Similarly, precipitation will focus over slopes where orographic forcing is strongest.
Central Valley (Kahului, Spreckelsville):
HIGH SURF ADVISORY IN EFFECT UNTIL 6 PM HST THIS EVENING. Mostly sunny. Highs 85 to 90. Northeast winds 10 to 20 mph.
Leeward West (Lahaina, Ka`anapali):
HIGH SURF ADVISORY IN EFFECT UNTIL 6 PM HST THIS EVENING. Mostly sunny. Isolated showers in the morning. Highs 81 to 88. Northeast winds 10 to 15 mph. Chance of rain 20 percent.
Windward West (Wailuku, Waiehu):
Mostly cloudy with scattered showers. Lows 58 to 74. East winds 10 to 15 mph. Chance of rain 50 percent.
Windard Haleakala (Hana, Haiku, Makawao):
Mostly cloudy with scattered showers. Lows around 72 at the shore to around 53 at 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.
Leeward Haleakala (Kihei, Wailea, Makena):
HIGH SURF ADVISORY IN EFFECT UNTIL 6 PM HST THIS EVENING. Mostly sunny. Isolated showers in the afternoon. Highs around 85 at the shore to around 68 at 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.
Partly cloudy with isolated showers. Lows around 50 at 7000 feet to around 47 at the summit. Northeast winds around 15 mph. Chance of rain 20 percent.
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