Waves, Winds, Weather compliments of Leahi Health Beverages
Your exclusive SNN Obs for this Saturday Aug. 30th 9am update
Light trades this morning with a mix of sea breezes and light trades starting up. Another hot, beautiful day.
Kaisers, Kewalos (check our Bowls-Courts CAM); light trade wind texture;. Diamond Head: Dropping on the SSW at 2-3'+ and so far it's good light sideoffshore ENE trades (see SNN Cam). Sandy's: Dropping on the SSW and E wrap at a good clean 2-3'+ and plenty barrels and breaking all over with closing shorebreak. East: Makapu'u: Dropping from the ENE swell the slightly bumpy 1-3'. Some waves on the outside but most on the left to Ala Moana,
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THE WHERE, WHEN & WHY OF HAWAII’S WAVES & WEATHER: A VIDEO PRESENTATION BY SNN
Winds Statewide in a glance ...go HERE (this link is also the 4th drop down under weather)
Aug 29, 2014 4:00 AM HST
Easterly swell is still forecast to build over the Hawaiian coastal waters today, and advisory-level surf also will affect south-facing shores. Interaction between the long-period east and south swells may produce strong currents in some areas. The surf from both swells will decline slowly through the weekend.
With trade wind speeds more likely to diminish than to increase through the first half of the forecast period, it is doubtful that they will approach the criterion for a small craft advisory. However, the long-period easterly and southerly swell could produce locally large and confused seas.
High surf advisory until 6 am HST Saturday for Niihau, Kauai windward, Kauai leeward, Oahu south shore, Waianae coast, Oahu Koolau, olomana, Molokai, Lanai makai, Kahoolawe, Maui windward west, Maui leeward west, Maui central valley, windward Haleakala, leeward Haleakala, Kona, south Big Island, Big Island north and east.
The trade winds will weaken further, becoming light by early next week. A trough moving over the southeast half of the state may increase clouds and showers through about noon today. Over the weekend, sea breezes will encourage cloud buildups and a few showers in island interiors by day, while land breezes bring clearing at night. The trade winds may start to return by the middle of next week, though they will remain on the light side of average for some time.
Surface observations around the main Hawaiian islands reported very light trade winds. Precipitation across the state remained sparse, with individual totals also diminishing through the night. Since the inversion stayed high, and precipitable water adequate, these dry conditions probably were supported at least in part by land breezes.
Although a mid-level ridge prevailed to the southeast of the islands, a broad trough was present to the northwest through northeast. Most likely it was this feature that encouraged active towering cumuli to develop near 30°N.
Satellite estimates showed a plume of moister air approaching Maui county from the east, and the cloud feature associated with this plume developed considerably during the past few hours. In-station analysis suggested that this feature remained a trough rather than a closed low, at least near the surface, but in any case it may enhance rainfall later today as it moves ashore over Maui and Hawaii counties. Pops and associated fields have been increased accordingly.
Guidance predicted additional moisture surges to reach the state periodically into next week, though with time the different solutions ended up following different periods, complicating a deterministic forecast. With trade winds very weak by Monday, diurnal showers produced by sea breezes may dominate weather from day to day, with the moisture surges only amplifying the magnitude of the daily event.
In any case, ridging aloft will expand over the islands from the southeast during the weekend, so by next week subsidence will start to crush down the inversion. However, a front north of 30°N will keep the surface ridge anchored near the islands well into next week, so the trade winds will recover only very slowly.
BIG SURF PICTURE 8/26/14
The Jet down under has been dominant with equatorial bound (ENE) flows leading to plenty surf, but the last few days its been zonal (west to east) with 2 branches staying the same most this week. By Thursday/Friday there’s another ENE tilt which will enhance a big storm but it'll be sending much of the energy off to our east since the equatorbound flow is far off NZL to under French Polynesia.
Recent: We’ve had nonstop surf for about 2 weeks; 2 Lows tracked SE of NZL Thursday 8/7 and these sources created surf the 1st weekend for the Dukes Oceanfest! Then a powerful Low a few days after with 55kts saw into our window SE of NZL hugging the East coast with a captured fetch. We got 18 sec forerunners Wed the 20th reaching 3’ 15 sec swells or 2-4+ SSW surf Thursday midday and the final Dukes weekend…one of the best weeks for the OceanFest in over 5 years.
Currently, we saw some 4’ sets from the SSW this past F-M from 2 sources: a gale 40kt storm east of NZL mid August. Her fetch head got to 3500 miles away which allowed for head high sets. Then a stronger system further SE of NZL with 47kts added more size over the weekend and into Monday. Some spots peaked 5’ over the weekend but these were special cases/spots. Things level off to head high Tuesday.
Next: Another compact Low SE of NZL tracked east again last Monday-Tuesday and will keep us at 3’ solid before a SSW swell arrives Wednesday.
Next: The Jet set up a long wave trough from Wednesday the 20th. We also saw a big High in the Taz which created solid winds in between the High spinning counter clockwise next to the Low spinning clockwise (opposite spins from the NPAC). This allowed a huge fetch area east of NZL last Thursday-Saturday. The head of the fetch got to within 3000 miles which is about 1000 miles closer than the usual. This means less ocean swell decay over distance and another round of advsry surf filling late Wednesday peaking Thursday into Saturday and even Sunday…High Surf threshold for South swell is 8’ crest to trough which is what typical surfers look for. The NS needs 15’ or twice the size which most surfers don’t look for. Why the large difference is likely extra safety precautions where populations are greatest.
Next: : Models backed down big time on their output a week ago for a new event early Sept. A broad gale Low far east of NZL reached near Tahiti last weekend. Now, it’s going to be 1-3’ South Sunday-Tuesday.
Last couple: Low confidence of models showing a big broad storm up off the Ross Ice Shelf Wed the 27th which fades fast and followed up fast by a much bigger Low Thursday. The issue is the ENE track but side band swell should hit 3 maybe 4’ with long periods Thursday sept 4-6th. Let’s take a better look this weekend.
The weak Jet up North is continuing it’s summer position with poor potential for swell enhancement, and tho’ she’s elongated the winds are too light for anything. Most the deeper troughing occurs under the gulf toward the end of the 7 day forecast.
Recent: It’s been quite and average after the long run of Typhoon West swells and Hurricane N swells making Aug the best in memory. Reliable sources like Pat Kelly with over 40 years up there plus, a former NS Capt and SNN eye’s on the country claimed it.
Next: East wrap from hurricane Maria will send long 2-3’ 14-16 second periods producing surf up 4’ around Kahuku and less to select spots toward Haleiwa starting Thursday and into the weekend.
Next: nothing is on the models out over 10 days.
Recently, small 2’ East swell have been dominant but that’s increasing today from 2 Tropical systems: Lowell and Karina off Baja and weakening. Then it goes up big time with a rare push of 14- 17 second East surf from Cat 5 Hurricane Maria tracking ENE off of Baja (see below). Surf on the windward spots will reach as high as 7’ local scale. We also have two 1030mb High up beyond 40 north or 1200-1500 miles away keeping us in the typical trade wind pattern. So after this upcoming run its back to normal by next Wednesday.
Tropics: Cat 5 Hurricane Maria built this past weekend SSW of Baja and is expected to move NW and weaken to a Tropical Storm before Friday staying over 1200 miles to our NE. She built 40’ seas and will send off some of that High surf advsry East swell Thursday-Saturday. The main feature will be the long periods which refract and shoal off the ocean floor much more than the typical 8-10 sec windswell we usually ride. Watch for spots to break with more power and current.
FETCH: Often called the fetch length, is a term for the length of water or distance over which a given wind direction has blown. Fetch length along with the wind speed (or strength) determines the size of waves produced. The longer the fetch length and the faster the wind speed, the larger and stronger the wave will be and vice versa.
CAPTURED or FOLLOWING FETCH: Not only does the fetch length determine the power and energy of the wave. Additionally, if the winds/fetch are blowing in the same direction as during the wave's or storm's lifetime, the wave will in turn be even stronger. The fetch is related to the orbit of the wave and track of the storm.The longer the wind drags along the sea the more energy the wave will have. This can be seen not just in vertical height measurement but in wave period (the measurement of waves through time).
WAVES PERIOD:Time, in seconds, between the passage of consecutive wave crests past a fixed point. In general the longer the period the bigger the wave. Windswell or 'close interval' swells are under 10 seconds. Big 'ground swells' are 17-20+ seconds (note: a 20+ second swell needs storm force 50+kt winds blowing over a 1500 mile fetch to be fully developed' into 20-25' beasts; these 20 second waves can be felt 1000 feet down!). This is why they jack so much more, pulling large amounts of H2O off the outer reefs.
More generic marine definitions click this link http://www.prh.noaa.gov/hnl/pages/marinedef.php
....All surf height observations and forecasts are for the full face surf height, from the trough to the crest of the wave.
|North-Facing Shores||15 Feet (8')||25 Feet|
|West-Facing Shores - Big Island||8 Feet (4'+)||12 Feet|
|West-Facing Shores - Remaining Islands||12 Feet (7')||20 Feet|
|South-Facing Shores||8 Feet (4'+)||15 Feet|
|East-Facing Shores||8 Feet (4'+)||15 Feet|