Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
501 FXHW60 PHFO 140155 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 355 PM HST Fri Sep 13 2024 .SYNOPSIS... Gradually strengthening trade winds will become locally breezy by the weekend, delivering just a few showers, mainly to windward areas. An increase of showers are expected on Monday especially over windward Big Island, where periods of locally heavy showers will be possible. && .DISCUSSION... As the weak trough far north of the state continues to move west, high pressure will build over the area. This will allow trade winds to pick up a notch this evening into Saturday. Breezy trade wind weather is expected for the weekend with scattered showers over windward areas primarily during the night and morning hours. Leeward areas should remain mostly dry with the exception of the kona slopes of the Big Island, where scattered showers are expected each afternoon. Starting Sunday night, a weak trough should move in from the east and will likely bring an increase of showers mainly over the Big Island. Latest GFS model is showing over 2 inches of precipitable water moving into the Big Island on Monday. Although details are uncertain, windward areas of the Big Island could see some heavy showers late Sunday night through Monday. For rest of the state, the windward side should see an increase of showers, but rainfall amounts should stay moderate. Although showers will be focused over windward and mountain areas, dewpoints should increase to the low 70s across the state. This will make temperatures feel warmer than usual on Monday. As the plume of moisture moves away from the state Monday night, our typical moderate to locally breezy trade wind weather should return on Tuesday and hold through most of the week. && .AVIATION... Moderate to locally breezy trade winds with VFR conditions expected in most areas across Hawaii through the forecast period. Brief periods of MVFR conditions are likely for low ceilings and showers over localized windward and mountain locations. Through this evening, AIRMET Sierra is posted for tempo mountain obscurations across portions of the Big Island. No other AIRMETs are currently in effect. AIRMET Sierra may need to be expanded for portions of the smaller islands overnight. && .MARINE... Fresh to locally strong trades continue into next week as broad high pressure develops over the NE Pacific. The Small Craft Advisory remains posted for the typical windier waters of Maui County and the Big Island through Sunday night may eventually require an extension. Flat conditions return to N shores tonight into next week as the existing tiny N swell fades. Short period surf trends up for E facing shores due to returning trades. Nearshore PacIOOS buoys at Barber`s Point off of Oahu and Kaumalapau off of Lanai indicate tiny long period S swell dominating the medium to longer period bands. This swell will generate small surf along S facing shores over the weekend with a downward trend expected early next week. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 AM HST Monday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...Kino AVIATION...Shigesato/Farris MARINE...JVC