| Current Conditions | ||
| Temp |  | 6.5 C |
| RH | | 8 % |
| Wind | | NNE 25 mph |
| Road | | Open (4x4) |
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Hawaiian Islands Synoptic Discussion and Guidance 345 FXHW60 PHFO 042002 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 1002 AM HST Tue Aug 4 2020 .SYNOPSIS... Moderate to breezy trade winds will continue through the week, and may get a little stronger by the weekend. The trade winds will deliver passing low clouds and showers that will primarily focus over windward areas, with a few showers occasionally spreading leeward on the smaller islands. Increased moisture and a passing disturbance aloft are expected to bring an uptick in showers from late tonight into Friday. && .DISCUSSION... No significant changes to the forecast with the morning update. Some very minor tweaks to the winds, with winds around the Big Island and Maui County today expected to be just below Wind Advisory levels. High pressure to the northeast has a ridge to the north of the islands, and is driving the moderate to locally breezy trade winds across the region. Satellite derived precipitable water (PW) shows the decrease in PW that was observed in the overnight soundings. The satellite is picking up on an increase in PW about 200 miles upstream of the islands. Infrared and visible satellite shows little change in the clouds in that area, but it could indicate more moisture available as that area interacts with the islands later tonight or tomorrow. The current forecast reflects the uptick in showers that is possible with that increased moisture. The trade winds are expected to persist through the week with a slight trend down this weekend. Dew points will likely creep up into the lower 70s, raising humidity and giving the air a warmer feel, even with the trades blowing. A mid-level trough, loosely associated with that increase in PW, will also move over the islands from the east, destabilizing the lower atmosphere. The combination is expected to lead to periods of enhanced showers, mainly over windward areas, with the trades driving a few rain drops leeward on the smaller islands. The Big Island's leeward slopes will see afternoon and evening clouds developing in response to sea breeze convergence that will drop a few showers. By the weekend, a return to a more typical trade wind pattern is expected, with mainly brief windward showers as moisture gradually diminishes. High pressure north-northeast of the islands will also strengthen, driving increased trade winds. && .AVIATION... An elongated ridge of high pressure north of the islands will allow for moderate trades to persist through the remainder of the day. This flow may lead to tempo moderate turbulence along the lee of the mountains. Expect mainly isolated showers over windward locations through this afternoon, with coverage increasing to scattered tonight. Brief MVFR ceilings and visibility remain possible with this activity. AIRMET TANGO remains in effect below 8000 feet for areas over and immediately south through west of mountains for tempo moderate turbulence. && .MARINE... Ridging positioned to the north of the islands through the weekend will support locally fresh to strong trade winds. A Small Craft Advisory remains in effect for the waters around Maui County and the Big Island over the next several days. Small, long period southerly swell will arrive through the week with surf heights remaining below advisory levels. A short period southeast swell will persist through the week and maintain slightly elevated surf along exposed shorelines. Easterly trades will continue to produce elevated surf along east facing shores. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST Wednesday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...M Ballard AVIATION...Thomas MARINE...Blood Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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