Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
004 FXHW60 PHFO 041924 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 924 AM HST Thu Jul 4 2024 .SYNOPSIS... Moderate trade winds and a stable pattern of mainly light windward showers will prevail through much of the week. && .DISCUSSION... A moderate to locally breezy trade wind flow is pushing through an area of slightly active showers. Overnight rainfall totals mainly ranged from a quarter to a half inch over the wetter windward stations, and aside from a handful of sites on Oahu, most leeward areas were dry. The shallow moisture fueling the showers is only about 9,000 to 10,000 ft deep and contains precipitable water slightly above the seasonal average of around 1.3 inches. Drier air can be seen pushing westward over the islands on satellite imagery this morning. As a result, a decrease in rainfall is due this afternoon. A very stable trade wind weather pattern will dominate tonight into early next week. The broad surface ridge to the north that is driving the trade winds will weaken tonight and Friday, leading to a slight decline in winds that will hold through the weekend. A strong mid- to upper-level ridge parked over the region will produce stable conditions with an inversion fluctuating between 5,000 to 8,000 feet, and precipitable water will likely fall below seasonal average. As a result, expect modest windward rainfall, and aside from a few afternoon showers on the Kona slopes of the Big Island, leeward areas will be rather dry. No big changes are noted 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 showing a possible increase in showers around Tuesday and Wednesday. && .AVIATION... Moderate to locally breezy trades will continue for the next couple of days. Showers and brief MVFR conditions will generally be confined to windward and mauka locations, but a few showers may make it over to leeward areas at times. Otherwise VFR conditions should prevail. No AIRMETs are currently in effect. && .MARINE... The pressure gradient over the state will weaken over the next couple of days as troughing develops over the eastern Pacific. Moderate to locally strong trades will hold through today then ease slightly to gentle to fresh Friday then hold through the weekend. A Small Craft Advisory (SCA) remains in effect for windy waters around Maui County and the Alenuihaha Channel through today. Borderline SCA conditions may persist for the Alenuihaha Channel into Friday. Will continue to monitor all available observations and make a decision with the next package. Moderate to locally strong trades will build back over the state next week as the disturbance weakens and dissipates. 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 small fetch of strong northeast winds off the U.S. Pacific Northwest coast will generate a very small, medium period northeast swell that is scheduled to arrive over the weekend along with a small, medium period northwest swell. Higher than normal water levels, in tandem with new moon tides, has produced higher than normal water levels around Big Island. Water levels have exceeded 3 feet above Mean Lower Low Water (MLLW) during the past few afternoon`s high tides. This will continue to create minor coastal flooding issues through the weekend. Peak water levels of around 3.5 feet are expected during periods of high tides. Therefore, a Coastal Flood Statement highlighting this flooding will remain in effect for Big Island`s coastal zones for the remainder of the week. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST this evening for Maalaea Bay- Pailolo Channel-Alenuihaha Channel. && $$ DISCUSSION...Wroe AVIATION...Farris MARINE...Almanza