| Current Conditions | ||
| Temp |  | 7.0 C |
| RH | | 7 % |
| Wind | | NE 19 mph |
| Road | | Open (4x4) |
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Hawaiian Islands Synoptic Discussion and Guidance 633 FXHW60 PHFO 211941 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 941 AM HST Sun Apr 21 2019 .SYNOPSIS... Locally breezy trade winds will continue through Friday, bringing periods of clouds and showers to windward areas, while leeward areas remain mostly dry. Lighter winds are in the forecast for next weekend, which may allow afternoon clouds and showers to form over interior and leeward areas. && .DISCUSSION... A surface high will remain nearly stationary far NE of the islands through Tuesday before weakening and moving E on Wednesday. A new high pressure cell will pass far N of the area around midweek, and the pressure gradient over the islands will change little, with locally breezy trade winds persisting into Friday. As this high moves into the NE Pacific by the end of the week, its associated ridge will be shunted toward the islands by an approaching front. Winds will weaken and shift to the SE or S, potentially bringing an increase in low-level moisture next weekend. A mid-level ridge will be near or over the islands through the upcoming week, then shift E by next weekend as height falls over the islands are supported by the development of a closed low aloft to the NW. A subsidence inversion based near 6000-7000 feet will change little as the ridge persists, thus maintaining a stable island atmosphere. The inversion will be high enough however to allow trade wind showers to occasionally dampen windward areas, most likely during nights and mornings. Little in the way of leeward rainfall is expected, except for leeward Big Island, where a few afternoon and evening showers will be possible. Low cloud coverage upstream of the islands has decreased over the past 6 to 12 hours, and fewer windward showers are expected today as compared to yesterday, with rain chances expected to be quite low over windward Big Island, where upstream low cloudiness is minimal. The short term forecast will be updated to account for the latest satellite trends. && .AVIATION... A ridge of high pressure will remain far northeast of Hawaii and drive fresh trade winds over the next few days. AIRMET Tango remains in effect for moderate turbulence below 060 over and downwind of the terrain due to the trade winds. These conditions are expected to hold in place today and possibly through Monday. Trade winds will carry in periodic clouds and showers that will focus over windward and mauka sections. Brief MVFR ceilings and visibilities, and mountain obscurations may occur within the showers. && .MARINE... For the most part, a ridge north of the state will maintain breezy to occasionally strong trade winds through Thursday. A front passing well north of the state today will weaken the ridge slightly and will cause the winds to ease across select windward zones and channels later this afternoon. A Small Craft Advisory (SCA) is in effect for most of the waters near Maui County and the Big Island through today, and for the typically windy areas around Maui and the Big Island through Monday. The SCA for these latter areas will likely be extended due to the strong trades. Surf along all shores is expected to remain below advisory levels for this week. A small west-northwest swell will provide small surf along north and west facing shores for the first half of the week. A series of small south swells will provide small surf starting Monday and will likely continue through most of the week and into the weekend. Surf along east facing shores will hold steady in the small to moderate range through Thursday due to the breezy to locally strong trades. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST Monday for Maalaea Bay-Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. Small Craft Advisory until 6 PM HST this evening for Kaiwi Channel- Maui County Windward Waters-Big Island Windward Waters. && $$ DISCUSSION...Birchard AVIATION...Foster MARINE...Kinel Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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