Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
951 FXHW60 PHFO 281946 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 946 AM HST Fri Jun 28 2024 .SYNOPSIS... An upper low will approach the islands and bring scattered enhanced showers and isolated thunderstorms with the focus over Kauai and afternoons over the interior Big Island. The atmosphere will stabilize early next week with weather returning to typical summertime trade winds with passing windward and mauka clouds and showers. && .DISCUSSION... Water vapor imagery shows an upper level low centered 550 miles northeast of Hawaii and approaching. At the surface, high pressure to the north is driving moderate to locally fresh trade winds. Visible satellite and radar show an area of showery low clouds over Maui and Big Island this morning with the trades focusing them over the windward slopes. Drier weather persists across Kauai and Oahu this morning with windward clouds. Soundings from early this morning show weak stability holding on. The area of clouds and showers will linger through the day over Maui and Big Island as the trades move it westward. As the Big Island heats up today, isolated thunderstorms will be possible across the interior and leeward side. The upper low will approach Saturday and Saturday night coming close to Kauai before shifting north away from the area Sunday. The instability will be present through the whole weekend with 500 mb temperatures around -10 C to -11 C near Kauai, but moisture won`t be very significant with model precipitable water values only in the 1.2 to 1.3 inches. Thus, we are forecasting scattered enhanced showers with isolated thunderstorms mainly across the northwest end of the state, and for the interior Big Island. Trade winds will weaken slightly through the weekend and Monday as the high to the north temporarily weakens. The atmosphere will stabilize early next week with weather returning to typical summertime trade winds with passing windward and mauka clouds and showers. Most rainfall will occur during the nighttime hours, but no significant accumulations are expected. && .AVIATION... Moderate trades are expected to continue across the island chain through the weekend. Showers and low clouds embedded in the trades will bring brief periods of MVFR conditions over windward and mauka locations. Otherwise, VFR conditions should prevail. AIRMET Sierra is in effect for tempo mountain obscuration across the windward portions of most of the island chain this morning as a band of low clouds and showers moves in from the east. An upper-level low is forecast to move over the islands this weekend, resulting in increased shower coverage and likely need for AIRMET Sierra periodically throughout the weekend. && .MARINE... High pressure north of the state will maintain moderate to fresh trade winds through the weekend. The trades are expected to strengthen back to fresh and strong levels early next week, and a Small Craft Advisory will likely be required for the typically windy waters around Maui and the Big Island by Monday. A series of south swells will keep south shore surf near the summertime average through Saturday. Surf will lower below normal levels much of next week. A small background south swell is possible towards the middle of next week. Typical mostly flat summertime conditions will continue along prevail north facing shores through late next week. East shore surf will remain well below normal through the weekend, then trend up and closer to seasonal levels next week as the trades strengthen over and upstream of the islands. && .HFO WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Foster AVIATION...TS MARINE...Kino