THE LATEST IN DEPTH VIDEO PRESENTATION OF HAWAII'S WAVES,WINDS & WEATHER FROM SURF NEWS NETWORK & SPONSORED BY HAWAIIAN SOUTH SHORE

Winds Statewide in a glance ...just go HERE (this link is also the 4th drop down under weather)

May 18, 2013 3:30 AM HST

Synopsis
Trade winds will weaken today, and turn toward the north on Kauai and Oahu, as a trough develops near the islands. The trough will move slowly east this weekend, and light to moderate northerly winds will spread to Maui county, while light south winds will prevail near the Big Island. With light winds, clouds and showers will favor afternoon hours, and will primarily affect leeward areas. The presence of the trough will help to intensify any showers that form over the islands the next several days.

Discussion
A somewhat unseasonable weather pattern, and low confidence forecast, are in the works for the next couple of days.

Currently, water vapor imagery shows a weakening low aloft moving slowly ESE just N of Maui county, with the low becoming increasingly ill-defined over the past few hours. At the surface, a weakening trade wind flow is being supported by a surface high about 1550 miles NE of the islands, but the latest surface analysis places a sharpening surface trough near Maui county that will become a primary player in island weather over the next several days. Despite weakening, the presence of the low aloft is maintaining a moderately unstable airmass over the islands, as seen in early morning soundings, and highlighted by the strong radar returns emanating from showers. Meanwhile, water vapor imagery shows a rapidly sharpening trough aloft N of the islands near 30°N 160°W, which will be an important player in island weather over the next several days.

Have introduced a slight chance of thunderstorms over interior and leeward Big Island for this afternoon, due to the instability and recent radar observations. In other areas, localized downpours are possible.

The forecast calls for the weakening upper low near the islands to move ESE before dissipating E of the Big Island later today, while the new trough aloft digs aggressively SE over waters N and NE of the islands. This strongly digging trough will develop into a closed low aloft by Sunday, with this low then meandering in an area about 550 miles NE of the islands into the middle of next week. The proximity of the closed low will maintain a moderately unstable island airmass, and enhance any showers that develop. The low will linger N of the islands until the middle of next week before finally dissipating.

A weak surface low is forecast to develop NE of the islands in response to the developing low aloft, with a sharp surface trough extending southward over the islands. The trough will interrupt the trade flow, and turn winds to the N and NE over Kauai and Oahu by tonight, while winds near the Big Island veer to the S. As the trough slides E tonight and Sunday, the light to moderate N winds will spread to Maui county, with this general wind flow persisting through Monday. On Tuesday the surface trough over the islands will weaken, but light E to ESE winds are expected to prevail statewide for much of next week, as the trough lingers N of the islands.

BIG SURF PICTURE Wednesday 5/13/13 

NPAC  Looking above average from Saturday through next Saturday.

Currently: lingering N swell at up to 0-2' for Laniakea and 1.5' for other spots.

Next: A marginal gale floats east off the Kurils all week crossing the dateline Wednesday up above 40 degrees north or about 1000 miles away. We can expect a fun spring time 11 second, 2-3+ NW filling Saturday and holding 3' Sunday before fading next week.

Last: Models keep supporting a unseasonal Low off Japan tonight which will stall then track ENE about 2000 miles away; she fades near the dateline Sunday but not before pushing out some 14 second NW swell with easy 4-6' surf Wednesday afternoon. We may give it an upgrade as buoy forecast currently show 6' 15 seconds which is enough for "almost" 8' at focal reefs like Sunset. Long range fantasys need focus.

(See HERE)

SPAC  It has been a really good spring with half a dozen swells aready but now it's really 'up there' in the ratings.

Currently: its cranking 4-6 from the S to SSW with higher sets and buoys 5' 17 seconds. So some reefs hit 8' today.

Buoys popped Wednesday nite at  20 sec forerunners from a rare run of SSW to S swell. Ascat wind measurements confirm a big storm with a good ''following fetch' on its NE track up and then out from the east coast of NZL this past Thursday-Saturday. Seas are about 35-40' and winds were solid 45kts over a wide area. We'll see our 1st of 4 advisory SSW swells filling late Thursday to solid 4' and even 6' at 'select reefs; a peak of 5' open ocean 16-18 second event (country hits 8' with this kind of reading). Our guesstimate peak on Friday afternoon is 4-7' surf (2.5 times overhead) into Saturday and even Sunday since the system stalled.

Next: This giant storm stalls or occludes over the weekend of the 18th more to our South allowing for another shot of lasting South swell in the 3-6' range but with 15 seconds.

Next: Another Low has its fetch off to the SE of NZL Monday-Tuesday 5/14 pushing up some solid 3-5+' South by Monday-Tuesday 5/20-21. She'll be a notch smaller than the 1st pulses.

Next: The final shot from this 4 swell series is filling late Tuesday peaking Wednesday at 3-5' then down 2-4' Thursday....

Last: we go into a relatively quite period till further notice. But models have a more background 1-3' South surf  with 15 seconds (2' open ocean) from Friday afternoon into Monday; this is from more distant zonal storms.

East Shores: Strong 1028 mb High to out NE fixes out weather and waves. Up to 3' is the trend from the fresh NE winds and N swell.

Tropics: This past Thursday model have a storm moving west under Baja . She dies off this Sunday as soon as she hits cooler water.

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.