| Current Conditions | ||
| Temp |  | 2.3 C |
| RH | | 14 % |
| Wind | | NE 17 mph |
| Road | | Open (4x4) |
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Hawaiian Islands Synoptic Discussion and Guidance 321 FXHW60 PHFO 230151 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 351 PM HST Fri Jun 22 2018 .SYNOPSIS... A strong high pressure system will pass through the Central Pacific basin this weekend reinforcing the ridge north of the islands and producing breezy to locally windy trade winds through next week. Expect typical windward and mauka clouds and showers with brief periods of showers passing through leeward areas. && .DISCUSSION... Clouds and showers continue to drift through the region today favoring windward and mauka areas. A strong high pressure center far north of Hawaii will move eastward across the Central Pacific basin this weekend reinforcing the high pressure ridge roughly 1200 miles north of the Hawaiian Islands. Water vapor satellite imagery shows a weak upper level low just east of the state, this low will drift over the islands on Monday. This low center remains fairly weak with little impacts to our weather pattern. The ridge north of the islands will produce deep east to northeasterly trade winds over the state through at least next week Friday. The upper air soundings this afternoon show the trade wind subsidence inversion at around 8,000 feet, the inversion height will cap cloud heights, and periodically range up to 10,000 feet through the week. The trade wind inversion heights in the 8,000 to 10,000 foot range is high enough to support likely showers along windward an mountain slopes with brief periods of showers passing over leeward sections of each island through the week. Models are in good agreement with this high confidence summer trade wind weather pattern. Breezy trade winds will continue to push vog (Volcanic smOG) emissions south of the smaller islands. Any volcanic ash from Kilauea and the East Rift Zone vents will likely drift towards the southwest over the Kau district. && .AVIATION... Strong trade winds will continue into this weekend as high pressure builds far northeast of the state and drifts eastward. VFR will prevail over most sections of the islands, with brief MVFR conditions likely in windward and mauka areas in passing showers. AIRMET SIERRA is no longer in effect for mountain obscuration on the Big Island. AIRMET Tango remains in effect for low level turbulence over and SW of all islands. && .MARINE... A 1030 mb surface high about 1300 nm NW of the islands will move E and strengthen, passing far N of the islands as a 1035 mb high on Saturday. The high will continue to move E with little change in central pressure through early next week, and then remain in its climatological position far NE of the area for much of next week. Although the high will pass far N of the islands (moving E along 40N), and a front will lie between the islands and the high, trade winds are expected to strengthen through Saturday, and remain fresh to strong into Monday. A subtle dip in the winds early next week may precede another slight increase around the middle of the week as the high wobbles around to the distant NE. A Small Craft Advisory is in effect for the windier areas, and may need to be expanded to include other zones as winds peak this weekend. Short-period wind waves driven by the local and upstream trade winds will bring increasing surf to E facing shores into Sunday, with peak surf heights expected to approach, but remain below, advisory level heights into early next week. Persistent trade winds in the SE Pacific will send a small short-period swell toward the islands from the SE, but the Big Island tends to shadow the other islands to some degree. Otherwise not much in the way of long-period swell is expected until the middle of next week, when a new S swell is expected to arrive, producing surf near advisory levels along S facing shores around Thursday. The updated Oahu Surf Discussion (SRDHFO) contains additional details. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST Sunday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. Small Craft Advisory until 6 PM HST Saturday for Kaiwi Channel- Maui County Windward Waters. && $$ DISCUSSION...Bohlin AVIATION...TS MARINE...Birchard Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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