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Your exclusive Observations for Saturday April 19th at 7am update
Skies a little cloudy at times today but moderate trades at 10-20+ filling in. Only isolated light windward and mauka shower activity.
Quote of the Week "I need to feel it as an education to put myself in the zone" Pete Mel on Mavericks Invitational 2014.
THE WHERE, WHEN & WHY OF HAWAII’S WAVES & WEATHER: A VIDEO PRESENTATION BY SNN
Winds Statewide in a glance ...just go HERE(this link is also the 4th drop down under weather)
Apr 17, 2014 3:30 AM HST
High pressure north of the area will keep moderate trades across the islands through the next couple of days. Winds are expected to increase during the upcoming weekend and into early next week as reinforcing high pressure develops north of the island chain. Clouds and showers will continue to favor windward and mountain areas. Leeward areas of the Big Island will see increased clouds and showers each afternoon and early evening.
Strong surface high pressure centered far N of the main Hawaiian islands is keeping the area under a trade wind weather regime. In the meantime, water vapor imagery still depicts a persisting weak upper level trough over the area, which may keep enhancing the trade showers especially at night.
Short range model solutions indicate a gradual reduction of pressure gradients during the next couple of days as the high N of the area migrates E and weakens. This will likely bring a decrease in trade wind speeds, which will remain moderate through the rest of the work week. The long range model solutions suggest an even stronger high pressure system building behind the current one, which intensifies as it moves N of the islands by Saturday. This should bring back stronger trades with breezy conditions returning during the upcoming weekend.
In general, expect trade wind showers to continue through the rest of the forecast period with rainfall focusing over windward and mountain areas. Only exception will be the leeward side of the Big Island where afternoon clouds and showers are expected as onshore develops each day.
A small swell from the west northwest will peak below advisory levels later today. No other significant swells are expected.
BIG SURF PICTURE 4/12/14 Saturday update
The Jet has a 150mph trough inbetween Japan and HI at 30-40N latitude or 600-1200 miles north of us. There's lotsa of broad weak Jet winds from the dateline to over Hawaii thus the wetter weather. A strong High bounces the Jet up and over HI Sunday into next week. Also a new trough moves our way of Japan again Monday allowing for slight potential for continued storm development. By Friday the 18th its very weak tho' extended across the NPAC to the west coast. Hinting of a long term quite period.
Currently, we have a nice sized high surf advsry level 15 second NW reaching heights of solid 8' or triple overhead for Pipe and Sunset. Winds are NE sideshore but hey its got power. The source of Saturday's peaking event was a broad gale near the Kurils last Sunday moving east making for 28' seas. This swell will drop a lot to about 3-4' maybe 5' Sunday morning.
Next: A Low pops on the charts Friday 4/11 near the Kurils Is again but this ones smaller and farther away (2200 miles). Winds are stronger but wont make up for the afore mentioned factors. She'll build Wed nite the 16th peaking 5-7' Thursday from the WNW.
Last: The Jet goes zonal mid April with quick eastbound Lows bring short lived smaller spring like/small NNW surf next Saturday. Keep you posted. Better shot of NW possible on Thursday the 24th.
Long range models love to fantasize. Meaning they run 'hot' making promises they can't always keep.
SPAC: The Jet is weak and zonal or west to east from Sat to Wed. the 16th when a weak NE flow shows esp by Friday-Sunday. The main push for swell will move out of our window.
Currently: Distant past sources make for background 14 seconds with just 1' swell...this leads to 2' surf for most spots thru next weekend. Below average.
Next: If long range outlook stands the test of time we'll get a 2' SSW Thursday the 24th from a marginal NE bound Low Thursday the 17th.
Last: Friday the 18th shows a large Low far south of Tahiti ramping to 35' seas by Saturday as it tracks ENE out of our window; maybe some long period 2-3' sideband SSE surf Saturday the 26th.
The Windward side see’s small 2' ENE wind swell at 8 seconds ramping to 2-4' this weekend esp Sunday into Monday the 14th from increasing trades from the building strong High. Chance of high surf advsy surf. Model hint of Trade fetch weakening Tuesday thus a weakeing windwave swell esp by Wednesday. Typical spring.
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|