| Current Conditions | ||
| Temp |  | 8.5 C |
| RH | | 21 % |
| Wind | | NE 20 mph |
| Road | | Closed |
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Hawaiian Islands Synoptic Discussion and Guidance 233 FXHW60 PHFO 251947 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 947 AM HST Sun Aug 25 2019 .SYNOPSIS... A trade wind weather pattern will continue through Monday, thanks to high pressure far north of the area. Trade winds will become lighter Tuesday through Friday as an area of low pressure develops far north of the area. Local land and sea breezes are expected to develop across some areas under this lighter trade wind regime. A new high is expected to build in far north northwest of the area next weekend with an uptick in trade winds expected. Clouds and passing showers will tend to favor windward and mauka areas with afternoon clouds and showers possible over the leeward Big Island slopes through the forecast period. && .DISCUSSION... Surface high pressure is centered far north of the state. This places the islands in a moderate to locally breezy trade wind environment. Aloft, there is a mid level ridge in place over the area. This is providing for a rather stable airmass to be in place across the state. Thus any showers that do form will tend to be on the lighter side due to inhibited cloud growth. The surface high will continue to keep moderate to breezy trade winds in place through Monday while the upper ridge will keep inversion heights low with only light windward and mauka showers expected. Afternoon and evening clouds and showers are also expected over the leeward Big Island slopes. During the Tuesday through Friday time frame, the high is forecast to weaken and move off to the northeast while an area of low pressure develops far to our north. This will cause our trade winds to weaken to the light to locally moderate range. Localized land and sea breezes may develop under this lighter trade wind regime. Meanwhile, the state is forecast to lie between a mid level ridge northwest of the state and a mid level trough just east of the state. Thus instability will be limited under this scenario. Shower activity will be highly dependent on incoming moisture availability and primarily focused over windward and mauka area. Daytime heating may allow for some afternoon shower development over interior areas as well as over the leeward Big Island slopes. As we head into next weekend, a new high is forecast to begin building in far to our north northwest while the area of low pressure moves off to the northeast. This should allow for an uptick in trade wind speeds across the area. Clouds and passing showers will tend to favor windward and mauka areas under this weather regime. && .AVIATION... High pressure north/northeast of Hawaii will continue to bring breezy trade winds to the state. So not much change from Saturday's weather except winds will tend to be a little stronger and there should be a few more showers in windward/mauka areas this afternoon and through tonight for Maui County and the Big Island. Will issue an AIRMET accordingly if necessary. The winds may also be strong enough on these islands to blow a few showers into leeward sections. AIRMET Tango continues for mechanical turbulence downwind of all the mountains below 8,000 feet. This AIRMET will likely continue through today and into tonight with little change in winds expected except the winds may be a little weaker Monday. VFR conditions are expected to prevail most of today with passing MVFR conditions in passing clouds and showers primarily over the windward slopes. There may be a more steady MVFR conditions for Maui County and the Big Island late today and overnight tonight as more moisture works into the windward areas of these islands. && .MARINE... Fresh to strong easterly trade winds will continue today as high pressure remains far north of the state. The Small Craft Advisory (SCA) has been expanded from the typically windy waters around the Big Island and Maui to briefly cover the Maui County windward and Kaiwi Channel waters today. Trades will gradually decrease through the first half of the week as the high weakens and drifts northeast. Advisory level winds will likely scale back to the usual windy areas Monday afternoon, and then drop completely by Tuesday. South shore surf will remain around the summer background level for the next few days as a southwest swell out of the Tasman Sea arrives Tuesday, peaks Wednesday and Thursday, then declines into next weekend. Though Hawaii is largely blocked by swells from this direction,some slightly higher, but inconsistent, sets are possible during the peak. Expect a slight and brief increase in east shore surf today as trades strengthen, followed by a gradual decline through the rest of the week. North shore surf will remain small through the week. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 AM 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. && $$ DISCUSSION...Burke AVIATION...Chevalier MARINE...TS Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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