Waves, Winds, Weather compliments of Big City Diner
Your exclusive SNN Obs for this Wednesday Oct 1st 620am Update
High Surf Advsry for the South Shores (8' face threshold or just over 4' Hawaii scale).
Clear and stablizing atmosphere. Light trades give way to cloud build up and seabreezes from about 11a for many areas. High tide 10a 2'. Low tide 6p 0.4'.
Chance of 5' bombers through Thursday. East: Makapu'u: holding the small East swell 1-2' breakin' inside and its smooth fun. Diamond Head: Up and holding on the 1ong period SSW at 3-4' and even 5' toward Black Point on sets on the take off & it's good-excellent with light offshores. (see SNN Cam). Sandy's: Up and holding on the SSW mixing with the 2' N and E with clean 3-4' sets at Generals, smaller at Full and half Pt and into the big close out shorebreak.
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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)
Oct 01, 2014 4:00 AM HST
A more stable airmass is expected to return to the islands through the next few days, though light winds and muggy conditions will prevail as a weak surface high pressure ridge stays near the state.
Mainly fair weather prevails over the islands early this morning, with isolated showers over the coastal waters. Early morning soundings from Lihue and Hilo still depict a rather unstable air mass, with little change in the moisture. Still expect to see less weather over the state through the next few days as air mass in the island vicinity will slowly become more stable. The overall synoptic surface weather pattern remains rather static in the island vicinity, as a weak high pressure ridge anchors just north of the islands at least through rest of the week. This will keep winds light in the island vicinity, allowing land and sea breezes to develop during night and day. Clouds will develop over the islands under day time heating. Since there will still be enough lingering moisture in the area, these clouds will probably bring measurable precipitation. Day time temperatures will also remain on the warm side and it may feel muggy due to the higher moisture. Showers will taper off in the evening, with clearing skies over the islands under night time cooling.
Latest forecast models still indicate the surface ridge may move south of the islands by early next week, as a surface front far northwest of the state is expected to advance more southeast. The ridge is expected to remain close enough to the islands to keep winds light. Therefore the current warm and muggy weather may persist through early next week.
Isolated TCU will continue through the early morning across the coastal waters, which are expected to diminish after sunrise. Vfr conditions with mostly sunny skies prevail over the islands this morning. Expect to see clouds and showers building over the islands by this afternoon. Airmet sierra for mtn obsc may be necessary later today as these cloud build ups occur.
The current south swell remains high enough to bring advisory level surf heights to south facing shores today, as the readings from the near shore buoy just southwest of Oahu stay rather elevated. As such, a high surf advisory remains in effect for the south facing shores of all islands until Thursday. Also a northwest swell will peak today with below advisory levels surf for north and west facing shores. A series of moderate northwest swells will arrive during the weekend and possibly lasting through early next week.
BIG SURF PICTURE
The Jet down under is still looking good for storm enhancement and steering toward the Islands. There’s a thick North branch and a decent southern branch flowing NE from off NZL the next few days. However, the high pressure are trying to squeeze out the troughs and block off NZL around Monday the 29th. Still, we get the N bound flow under Tahiti at this time allowing for more energy to come our way. Looking good.
Recent: We’ve been on the down trend to 1-2’ background SSE for awhile but that’s all going to change again for a super long round of back to back to back SW-South swell.
Next: A small bump from a Taz Sea fetch last Friday should pop 1’ 14 seconds on Barbers Buoy late Friday and rise into Saturday with long lulls of 1-3’ surf into Sunday. This will be overrun by the next source.
Next: The above Taz storm drifted east over NZL and gets out of to the NE side by Monday with a 40-45kt fetch nosing to about 3000 miles to our SSW or 1000 miles closer than the usual region of swell generation. Reinforcing SSW could hit 2-4’ Tuesday-Wednesday.
Next: Far below the above fetch is a much bigger stronger Low to the SE of NZL tracking ENE M-W and will add to the existing seas of the first Low to the NE. The apparent fetch from these two mergers gets nearly 1000 miles long creating yet another long lasting episode of fun in the sun and surf. Forerunners could pop 22 seconds Sunday night the 28th but it will be a slow rise over Monday-Tuesday. Still top reefs could see some 5’ sets Tuesday night and peak near 3-6’ on Wednesday-Thursday. We will have 2-3 days of high surf advsrys.
Next: Within the large Jet stream trough is yet another Big Low with its reinforcing broad 40-45kt fetch building 30’ seas Wed the 24th. Plus, the track is NE garnering a captured fetch (fetch points the same way as the storms center track) which helps grow the seas to their full potential. Thursday the track veers East under Tahiti so this swell will start out SSW and veer S. There’s a ton of storm activity far below French Polynesia so Tahiti’s going to score.
Next: Saturday the 27th shows a smaller compact Low tracking NE from below NZL which will bring up some 2-3’ SSW Saturday the 4th.
Last: Too early to claim but WW3 hints a whopper under Tazmania Oct 2nd…
Note: High Surf threshold for South swell is 8’ crest to trough and 15’ for NW swells. Why the large threshold difference is likely an extra safety precaution where populations are greatest.
Wednesday the Jet Stream is split 1200 miles off Japan with a larger trough looping up and down under the east Aleutians which leads to the first big NW hitting the NW coast. The fall regime change in the Jet is conducive to 3 rounds of fun NW swell. The split moves our side of the dateline by Saturday the 27th then consolidates and fattens up Sunday-Tuesday with a large dip SE near the dateline just 1200 nearing to 900 away. This will likely mean lighter winds and iffy weather early Oct. But it also spells WAVES.
Recent: It’s been tiny 2’ or less with minor pulses here and there from the NNW however, that changed today.
Currently: the surf has bumped up to 3’ Wednesday afternoon from the NW. We had a powerful Low off Kamchatka last Friday and it stayed over 2000 miles away limiting the size to max 3’. There’s also a N mixing from a nearby Low 1200 miles to our N. This is the same storm that intensifies as it tracked E toward the west coast so we’ll get N to NNE into Saturday. They’ll be 8 and even 10’ for N Cali and Oregon etc.
Next: Thursday-Friday the NPAC looks quite with only a tropical storm far off Taiwan building and tracking N to Japan. Hold on to this one.
Next: Upgrade for Saturday's storm: a Low spawns of the Kuril Islands with up to 30’ seas and a nice ESE track with a partially captured fetch; it reaches the dateline Sunday the 28th. Look for 5’ 16 seconds buoys oct. 1st refracting/shoaling swell for some 5-7' NW surf at Sunset Wed afternoon into Thursday morning. Could see some high surf advsry sets.
LAst: On Tuesday the 30th the tropical system above becomes a gender bender (warm to cold core Low) and feeds into the Jet energy near the West Aleutians intensifying Wed-Thursday as it moves N into the Bering sea. Still, tho’ distant its forecast to be powerful enough for 16 second forerunners and some more 4-6’ NW surf filling Sunday Oct 5th into Monday. Iffy confidence.
Windward side: With the return of the trades we’ve had a boost to 1-2’ ENE and we’ll also get some small N wrap from the above NPAC source. The surf should range from 2’ to maybe 3’ due also to a shear line moving South across the Island into Thursday. This is an abrupt change in wind speed and/or direction.
Tropics: A powerful system is on the charts Tues-Thu far off the Philippines moving NE. Too early for specifics but it's likely to be a typhoon. Things have calmed down off Baja.
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|