Waves, Winds, Weather compliments of Leahi Health Beverages
Your exclusive SNN Obs for this Wednesday Aug. 27th 635am
Much clearer today. Light NE trade winds fill to moderate paces. Predawn 1.5' High tide @ 5am dropping out to a .3' Low tide @ 11am pushing up the rest of the day to 1.8' at 5pm.
Kaisers, Kewalos (check our Bowls-Courts CAM); super clean straight light NE offshores. Diamond Head: Up Holding on the new SSW at 1-2.5' mostly (chest) occ 3' with nice lines and so far it's clean light NE offshores (see SNN Cam). Sandy's: Holding on the SSW and alittle more E wrap at a good clean 2-3' and plenty barrels and breaking all over. East: Makapu'u: Up a notch and holding the slightly bumpy 1-3' on generic local trades and now on the longer period 12 second East (T Storm Lowell). Waves 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 27, 2014 3:35 AM HST
Trade showers continue this morning with rainfall focusing over windward and mountain areas. The trades will gradually weaken Thursday through Saturday and allow for sea breezes to develop each day. This will bring periods of clouds and showers over leeward and interior areas through the weekend. Then the trades will strengthen again early next week with showers focusing back over windward and mountain areas.
Water vapor satellite imagery show an upper lvl low about 580 miles WNW of Kauai. The circulation on the E side of this low is pulling some of the scattered layered/high clouds near the ITCZ into the islands. Meanwhile, sfc high pressure remains centered far NNE of the aloha state and keeping a moderate trade wind regime across the island chain today.
At 3 am HST, radar data was showing showers just e/ne of the islands, bringing periods of rain over most windward and mountain areas, which will continue through the mid morning hours today. 12Z sounding data and mimic moisture analyses show pwats in general of 1.20 to 1.45 inches around the main Hawaiian islands, and a dryer airmass further upstream. Therefore, expect trade showers to continue this morning with rainfall focusing over windward areas, the Koolau range in Oahu, the W Maui mountains and windward Haleakala.
A brief drying trend will take place later today and tonight as the aforementioned drier airmass moves into the area. Then for the second half of the week, despite the arrival of the drier airmass, the global models show fair agreement regarding the passage of the remnants of former tropical cyclone Lowell far NW of the islands. This will temporarily weaken the trade wind flow and allow for sea/land breeze circulations to develop each afternoon Thu through Sat. Expect possible periods of afternoon and early evening showers, especially over interior and leeward areas.
For the long range forecast, the sfc high strengthens NNE of the aloha state with the trades gradually return to moderate lvls Sun into Mon. This will bring back a trade wind weather regime early next week with showers favoring windward and mountain areas, especially at night.
An increasing easterly long-period swell from hurricane Marie is expected to begin arriving later today and continue to build through Thursday night. This swell will bring advisory level surf to east facing shores by Thursday. Also, an increasing south-southwest swell is anticipated for tonight and into Thursday, bringing near advisory level surf over south facing shores through Friday. Strong currents could also develop with the arrival of these swells. The surf should begin subsiding Saturday and continue to decline through early next week.
With winds expected to diminish further, no small craft advisory conditions are expected through the holiday weekend. However, the long period easterly swell mentioned above could produce unusual conditions in east facing channels and harbors.
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|