Last Updated on Thursday, 06 March 2014 07:19
Winds Statewide in a glance ...just go HERE(this link is also the 4th drop down under weather)
Mar 06, 2014 4:00 AM HST
Light winds will become southwest and strengthen into Friday as showers increase ahead of a front approaching from the northwest. The front itself will bring heavier rain and northerly winds from Friday into Saturday. Trade winds will return briefly after the front passes, focusing showers onto windward slopes into Monday. A second, weaker front will bring another round of showers from Monday into Tuesday. Trades will diminish slightly Monday, but then will persist through the middle of the week.
Observations reported southeasterly winds starting to turn southwesterly across the main Hawaiian islands. Diurnal circulations also may be significant early today, but will be overwhelmed increasingly by the accelerating southwest flow. The inversion actually lowered overnight at Kauai, and the air mass there remained very much on the dry side of average, but moister air moved in from the east and southeast, as recorded by the Hilo sounding. Most cloud cover was stable, and precipitation sparse over land, but batches of showers persisted offshore to the east of the state, and sprung up to the west of the Big Island.
Aloft, extremely broad troughing prevailed over most of the eastern north Pacific ocean just north of the islands, though the deeper low remained much further to the north. Guidance agreed reasonably well that the trough will sharpen modestly into Friday as a massive ridge builds over the west coast of north America, providing increased, if unremarkable, support for the front approaching the islands from the northwest at the surface.
Southwest winds will increase ahead of the front from today into Friday, and pre-frontal showers are expected to do likewise. Thus, pops and related grids have been increased accordingly for today. The front itself will spread more organized, and perhaps locally heavy, rain southeast across the state from Friday into Saturday. Northerly winds following the front will become northeasterly fairly soon, carrying lingering moisture onto windward slopes through the rest of the weekend, especially over the Big Island, close to the dissipating boundary.
Brief mid-level ridging aloft will pass overhead from Sunday into Monday, and then a trough aloft will dig down toward the state from Monday into Tuesday, providing support for another approaching front. Although this feature is expected to be weaker than the one arriving over the weekend, pre-frontal showers may be more active in the easterly flow ahead of it. Winds behind this second front should become northerly, and then northeasterly again, fairly quickly. The resulting trade winds are expected to last through the middle of next week.
The NW swell diminished enough overnight so that the advisory was no longer necessary, and has been cancelled. Surf will remain below advisory levels today, but another large NW swell arriving Friday is expected to produce warning-level surf once again through Saturday, and then advisory-level surf on Sunday. Another long-period NW swell expected around Tuesday will produce advisory-level surf that may approach warning levels. The Oahu surf discussion has additional details that can be applied loosely statewide.
Seas will continue to diminish through tonight, before building to advisory levels in many zones on Friday from the increasing NW swell. This small craft advisory likely will be dropped on Sunday, though seas will increase again with the next NW swell on Tuesday.