Waves, Winds, Weather compliments of Surf n Sea
Your exclusive SNN Obs for this Monday Sept 2nd 630am
Another Gorgeous dawn and Super Light trades early this morning with Trades likely beating out sea breezes late morning-afternoon. High tide 1045am 1.9 drops out all day to a .6 at 615pm. New Intermittent 25 second South swell popped on buoys around midnight and our first NW hits Tuesday the 9th!
barrels and breaking over the line up; shorebreak still closing. East: Makapu'u: Down and Holding the ENE swell the relatively clean 1-2' on the left to light trade wind texture may compete with seabreezes pending land heating. Diamond Head: Down and dropping on the old S-SSW at 1-2 barely 3' with real good light sideoffshore ENE trades (see SNN Cam). Sandy's: Down and Holding on the South and ENE wrap at a nice clean 1-2' barely occ 3' and still some
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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)
Sep 02, 2014 4:00 AM HST
Synopsis Light trade winds will strengthen slightly today, and remain light to moderate for most of the upcoming week. The trade winds will deliver a few showers to windward areas, especially during nights and mornings.
Discussion Latest observations show that a light easterly flow prevails in the low levels, with winds light enough to allow localized land breezes. The winds are being supported by a distant high that is relatively weak, with weak troughs between the high and the islands contributing to a loose pressure gradient, as is the nearly stationary remnant circulation of Marie, about 1300 miles NE of the islands. Although skies immediately upstream of the islands from Kauai to Molokai contain only isolated showers, an area of showery low clouds lies over windward waters out to 200 miles E of Maui and the Big Island, moving W at 10 to 15 mph.
Today, abundant sunshine is expected over leeward areas, while windward areas will be partly cloudy with a few brief showers. Showers/clouds are expected to be a little more active through tonight over windward Maui and Big Island as the aforementioned area of moisture moves W. After this modest moisture source passes, limited moisture is expected through Thursday. Increased moisture loosely associated with the remnant of Marie passing far NE of the islands may increase windward showers from Thursday night through Saturday. A mid-level ridge near the islands will ensure that the atmosphere remains strongly capped at about 8 to 10 kft.
Trade winds are expected to be slightly stronger today as compared to the last 2 days, as the troughs NW of the islands weaken and the surface ridge to the N strengthens somewhat. The overall synoptic pattern does not support a strong trade flow this week however, but rather a light to moderate flow. Therefore, one of the biggest forecast questions over the next couple of days involves the strength of the trade winds, and whether or not afternoon sea breezes will become sufficiently strong/widespread to drive cloud and shower development over leeward and interior areas. Although a slight increase in leeward sky cover is in the forecast grids for the smaller islands today, no significant pops are indicated. Some uncertainty as to how this will verify. The leeward Big Island is the exception, where leeward clouds and showers are expected every afternoon and evening through the forecast period.
Marine Elevated surf will continue along S facing shores this week. Although surf is currently below advisory levels, forerunners of a very long period S swell /20-25 seconds' are expected to build today and tonight, although at low heights. Latest observations from buoy 51004 and the cdip buoy at Barbers Point show initial energy from this swell is beginning to arrive. As this swell fills in, it will produce surf near advisory levels along S facing shores, likely from Wednesday into Thursday. Will hold off on the issuance of an advisory to see if buoy data shows greater amplitude swell heights, but an advisory may be necessary later today for surf nearing advisory levels on Wednesday.
Forecast models are indicating that a fairly large gale low will develop NW of the islands this week, generating a NW swell that arrives around Monday. Since the low has yet to develop, too early for specifics, but resultant surf looks to remain below advisory level heights along N and W facing shores.
Winds and seas will remain below small craft advisory thresholds at least for the next several days.
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|