FXHW60 PHFO 310344 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 544 PM HST Mon Jan 30 2023 .UPDATE... We have updated the forecast to extend the Flood Watch for Kauai through midnight tonight. The threat of flooding should steadily diminish during the next few hours. Although light to moderate showers will continue over portions of Oahu and Maui County, the threat for heavy rain has diminished. Thus the Flood Watch for Oahu and Maui County has been cancelled. Last but not least, the Wind Advisory for Kauai has been cancelled. && .SYNOPSIS... The threat for flooding continues to diminish this afternoon and we will continue to see moisture decrease from east to west through tonight. Overall weather conditions will greatly improve by Tuesday, but will remain somewhat unsettled through Wednesday with afternoon clouds and showers. Some of the afternoon showers could produce a brief downpour. Trade winds may return by the end of the week with increasing showers over windward areas this weekend. && .PREV DISCUSSION.../ISSUED 406 PM HST Mon Jan 30 2023/ This afternoons satellite imagery shows an upper level low located roughly 350 miles southwest of Kauai with a cluster of thunderstorms on the northeast side of the upper low. This upper level low combined with a surface trough near Oahu is creating unsettled weather over the state. For this afternoon and evening, moisture will be gradually decreasing from east to west as the surface trough continues to lift to the northwest. Flood Watch for the Big Island has been cancelled and the Flood Watch for Oahu and Maui County will likely be cancelled soon as the heavier showers near Oahu exit the area this afternoon. For Kauai, we may have to extend the Flood Watch depending on what happens with the ongoing heavy rain at the moment. We do expected the heavy rain over Kauai to steadily decrease this evening with mainly moderate showers overnight tonight. But until then, moderate to heavy showers will continue across Kauai during the next few hours. Tuesday morning will look quite different compared to this morning with partly cloudy skies and much less shower activity. The weather pattern will still remain somewhat unsettled due to the upper level low lingering west of the state and a surface trough north of the state. With winds expected to be light and variable, we should see sea breezes develop by mid day with clouds and scattered showers developing over interior areas during the afternoon. Although isolated, we could see some brief downpours Tuesday and Wednesday afternoons with a slight chance of thunderstorms in some areas such as the Big Island slopes. Trade wind weather may return toward the end of the week as the trough dissipates and high pressure builds north of the islands. This high may push moisture associated with a frontal boundary over the islands Friday into the weekend and could bring in showery trade wind weather for this weekend. AVIATION... An upper level low southwest of Kauai, along with a surface trough near Oahu, will continue to bring scattered to numerous showers and scattered thunderstorms over all islands through this evening. MVFR and even brief periods of IFR ceilings and visibility will likely accompany the more robust thunderstorms. By tonight, the deeper moisture will begin to lift north of the main Hawaiian islands with just scattered showers remaining. Light to moderate easterly trades will prevail through the period. AIRMET Zulu remains in effect for moderate mid-level icing from over all islands. AIRMET Tango remains in effect for the entire area between 16000 ft and 36000 ft due for tempo moderate turbulence. && MARINE... A broad surface trough over Oahu will drift westward tonight as strong high pressure holds northwest of the state, resulting in declining fresh to strong northeast winds around Kauai and locally fresh east winds elsewhere. Heavy showers and thunderstorms will could locally stronger wind gusts, with the greatest threat around Kauai through the evening. Moderate to fresh east to southeast winds will develop late tonight and Tuesday as the trough moves away to the west, followed by a decrease in winds Wednesday and Thursday. Trades may rebuild Friday. A Small Craft Advisory (SCA) is now in effect around Kauai and for waters north of Oahu to the Big Island. The SCA around Kauai covers fresh to near gale winds that are expected to decline rapidly this evening, as well as rough seas produced by the declining northwest swell and a locally generated, short period northeast swell. For the remaining areas, the SCA is in effect for seas in excess of 10 ft that will likely drop a couple of feet overnight. The SCA will be dropped sometime Tuesday and may be required again as trade winds rebuild on Friday. The current long-period northwest (310 degrees) and the locally generated, short period northeast swell around Kauai and Oahu will decline through tomorrow. Combined seas of 14 to 16 feet at the Hanalei PacIOOS buoy are dominated by the short period northeast swell, which necessitates a High Surf Advisory (HSA) being kept in place through most of tonight on north and east facing shores of Kauai. A small pulse of northwest swell is due Wednesday and Thursday, followed by a moderate north-northwest swell this weekend. An out of season south swell is building along south facing shores and will provide surf around summertime average Tuesday into Thursday. && .HFO WATCHES/WARNINGS/ADVISORIES... Flood Watch until midnight HST tonight for Niihau-Kauai- High Surf Advisory until 6 AM HST Tuesday for Niihau-Kauai North- Kauai East. Small Craft Advisory until 6 AM HST Tuesday for Kauai Northwest Waters-Kauai Windward Waters-Kauai Leeward Waters-Kauai Channel- Oahu Windward Waters-Kaiwi Channel-Maui County Windward Waters- Alenuihaha Channel-Big Island Windward Waters. && $$ UPDATE...Kino DISCUSSION...Kino AVIATION...Thomas MARINE...Wroe