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 19, 2013 4:00 AM HST

Synopsis
A low aloft will linger northeast of the island chain producing unsettled weather through midweek. Locally heavy rain will be possible today with a slight chance for thunderstorms on the Big Island. A sharp trough will produce light background flow resulting in a land and sea breeze pattern near the surface in the short and midterm. Trade winds will return late this week.

Discussion
A complicated weather pattern persists across the state early this morning. Water vapor imagery shows a cold upper low north of the islands digging to the southeast. Meanwhile, at the surface, a sharp inverted trough has an axis across Maui and is stationary. To the north, a cold front is located about 75 miles away from Kauai and moving south towards the state at 15 mph. The front is being overrun by breezy northerly winds associated with high pressure behind it.

Current radar shows slow moving scattered showers directed in nearly a counterclockwise motion across the island chain. This is due to that sharp trough axis focused on Maui this morning. The greatest areal shower coverage is off the windward and southeast coast of the Big Island, and the least coverage around Kauai. Soundings from this morning show weak elevation inversions at 10 kft at Lihue and 14 kft at Hilo, with precipitable water values of 1.16 inches at Lihue and 1.53 inches at Hilo.

The light background flow resulting from the presence of the surface trough will allow sea breezes to build over the islands again today. Kauai will be the exception with moderate northerly winds expected. Clouds and showers associated with the approaching front should arrive in Kauai late this morning and afternoon, before washing out over Oahu tonight. For Oahu and Maui county, the sea breezes will bring clouds and showers onto the island interiors and leeward sections this afternoon and evening. The instability aloft from the upper low will cause locally heavy rainfall on all islands except Kauai today, though chances for rain will remain high on Kauai with the frontal passage. The Big Island will also be a focus for chances of heavy rain and a slight chance for thunderstorms given the pool of nearby moisture.

Land breezes will set in tonight pushing most of the clouds and rain offshore late. Oahu could still remain wet tonight as that front stalls and falls apart. The surface trough will linger near Maui through Monday, then slowly weaken and move off to the west. Aloft, a low will persist northeast of the area through midweek. Light winds associated with the surface trough and instability from the low aloft will continue this diurnal convective pattern over all the islands through Wednesday, and into Thursday for some leeward areas. There is a possibility of locally heavy showers across island interiors Monday and Tuesday given the proximity of the upper low, but not very confident in timing and location of these showers due to the complex situation. Will hold off on putting this in the forecast for now.

Long range models are in good agreement showing the trade winds becoming well-established by Friday, and locally breezy next weekend. The convective pattern will end and the trades will bring focus lighter showers to windward and mauka areas. Another trough aloft may dig down over the area next weekend and may enhance the trade wind showers.

Marine
Winds and seas are expected to remain below small craft advisory levels statewide this week. A series of swells will keep elevated surf along south facing shores through most of the week. Surf is expected to remain above the advisory threshold through at least early Monday morning, but may be extended into Tuesday if conditions persist. A marine weather statement remains posted for waves breaking near channel entrances and possible harbor surges.

Watches/Warnings/Advisories
High surf advisory until 6 am HST Monday for south facing shores of all 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.