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Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
759 FXHW60 PHFO 160153 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 353 PM HST Thu Aug 15 2024 .SYNOPSIS... Gentle to low end breezy trade winds will occur through the remainder of the day. Trades will strengthen to more areawide breezy magnitudes Friday through most of next week. Showers will typically favor windward and mauka locations, particularly during the overnight into early morning hours. && .DISCUSSION... The remnant of what was once T.C. Emilia in the eastern Pacific is moving across the local western waters as a broad open wave trough. Subtle mid level cooling brought on by a lingering upper level trough, its axis orientated from the islands off to the northeast, along with higher 850-700 mb layer moisture will keep higher-end windward/higher elevation rain probabilities in place through late Friday night. Offshore showers will primarily stick and dump the highest rain amounts over better east to northeastern exposed windward and mauka locations. Heat of the day interior (leeward) thicker clouds and increased shower activity (i.e., Big Island Kona regions) cannot be ruled out where localized afternoon sea breeze boundaries set up. Breezy trade winds are expected to return Friday and persist through next week as the weak open wave trough mentioned above travels west away from the state and the subtropical high northeast of the islands fills in and regains better control. After a relatively drier Saturday, general weak mid-upper level ridging, with periodic ribbons of passing higher moisture, may result in increasing shower coverage to begin next week. Confidence is still shaky on the development of a tropical depression or cyclone southeast of the islands next week. If a system does development and move across those waters south of Big Island next Thursday or Friday, the upcoming late week forecasts will trend more wet for the eastern end of the state. && .AVIATION... Moderate to locally breezy trades will deliver low cigs and SHRA to windward and mauka areas through the forecast period. MVFR conds can be expected in any SHRA but VFR should prevail. No AIRMETs are currently in effect. AIRMET Sierra may be needed for mtn obsc for windward locations particularly overnight and in the early morning hours with increased SHRA. && .MARINE... A weak surface trough passing by north of the islands will keep the trade winds at moderate to locally fresh speeds through this evening. As the trough exits the area, the trades will begin strengthening tonight. The trades should strengthen back to locally strong speeds late tonight, then hold at these levels through early next week. A Small Craft Advisory (SCA) is in effect starting midnight tonight for the typical windy waters around Maui County and the Big Island. The current small south swell should hold through tonight then gradually decline the next few days. Small background energy from the southeast is also possible during the next few days. A more significant south swell will arrive late Sunday and Sunday night, peak above the summertime average Monday, then slowly lower through the middle of next week. Seasonally flat to tiny surf is expected through early next week for north facing shores. East shore surf will remain below normal during the next couple days, then trend higher over the weekend and rise to near seasonal levels early next week. The combination of the full moon and water levels running around 0.5 ft higher than normal should produce minor coastal flooding each afternoon along the shorelines across the state beginning 8/18 and likely continuing through 8/20. A Coastal Flood Statement will eventually be needed as we get closer to the event. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory from midnight tonight to 6 AM HST Sunday for Maalaea Bay-Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...Blood AVIATION...Walsh MARINE...Kino