Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
497 FXHW60 PHFO 050649 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 849 PM HST Thu Jul 4 2024 .SYNOPSIS... Moderate trade winds and a stable pattern of mainly light windward showers will prevail through much of the next week. && .DISCUSSION... A broad surface ridge far north of the islands continues to drive moderate trade wind flow, while a deep mid- to upper-level ridge parked overhead maintains very stable conditions with an inversion based around 6500 ft. A narrow, low-level dry slot is moving into the islands this evening, which should decrease shower activity through the first part of the night. Small pockets of moisture are forecast to move through later tonight into Friday morning, though the stability will keep any rainfall amounts on the modest side. This stable, summertime trade wind weather pattern will dominate into early next week with only minor fluctuations in moisture levels and wind speeds. The surface ridge north of the state will weaken slightly tonight and Friday, leading to a small decline in winds through the weekend. The ridge aloft will remain anchored over the region, keeping stable conditions in place and a temperature inversion fluctuating between 5000 to 8000 feet. Precipitable water will be below the seasonal average, so rainfall will remain modest and windward-focused. Aside from a few afternoon showers on the Kona slopes of the Big Island, leeward areas will be rather dry. No big changes to the overall pattern are noted through the remainder of next week. Trades look to pick up Monday or Tuesday as the ridge to the north strengthens. Stable conditions will persist, but the GFS and ECMWF are hinting at a possible increase in showers around Tuesday. && .AVIATION... Moderate to locally breezy trades will continue through the next couple of days. SHRA and brief MVFR conds will generally be confined to windward and mauka locations, but a few SHRA may make it over to leeward areas. Otherwise VFR conds should prevail. No AIRMETs are in effect. && .MARINE... The pressure gradient over the local waters will remain weak the next couple of days in response to lower pressure over the eastern Pacific. As a result, moderate trades will remain below Small Craft Advisory thresholds the next several days. Trades will gradually strengthen to more fresh magnitudes the middle of next week as high pressure reestablishes itself northeast of the state and re- tightens the upstream pressure gradient. Sea heights will remain in the 4 to 6 foot range through early next week. No significant swells are expected from any direction for the remainder of the week. A series of small, medium period south southeast swells will keep south-facing shores from going completely flat through the weekend. A recent small fetch of strong northeast winds off the U.S. Pacific Northwest coast has generated a small, medium period northeast swell that is scheduled to arrive Sunday. Higher than normal water levels, in tandem with new moon tides, has increased water levels around Big Island and Maui County. Peak water levels of between 3.0 to 3.5 feet above Mean Lower Low Water (MLLW) are expected during periods of high tides. This will continue to create minor coastal flooding issues through the weekend. A Coastal Flood Statement highlighting this flooding threat remains in effect for both Big Island and Maui County. && .HFO WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...TS AVIATION...Walsh MARINE...Blood