Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
923 FXHW60 PHFO 270153 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 353 PM HST Wed Jun 26 2024 .SYNOPSIS... A stable trade wind pattern will persist through Thursday with breezy to locally windy trades. Periodic light showers will focus over windward and mauka areas during this time. An increase in shower activity and isolated thunderstorms will be possible over portions of the state from Friday into the weekend as an upper- level disturbance approaches and moves over the region. && .DISCUSSION... This afternoon, breezy to locally strong easterly trade winds continue to prevail across the islands, steered by high pressure that remains centered approximately 900 miles north-northeast of Kauai. Latest radar imagery shows mostly dry conditions statewide, other than a few light showers over windward locations and across the Kona slopes of the Big Island where low-level convergence has increased cloud cover this afternoon. Trades will remain breezy to locally windy through Thursday as the high pressure remains in place to the north. Impulses of moisture embedded in the trade wind flow will continue to favor windward and mauka areas, though rainfall accumulation will be limited. Aside from some brief afternoon and evening showers over Kona slopes of the Big Island, leeward areas will remain mostly dry. Guidance continues to show an upper-level disturbance moving near the islands Friday and then passing near the western end of the state this weekend. This disturbance will help increase instability and enhance our trade wind showers, particularly on Saturday night or early Sunday morning. Isolated thunderstorms will be possible over the slopes of the Big Island on Friday and Saturday afternoons, and over the far western end of the state on Saturday and Sunday as temperatures aloft cool. However, with precipitable water forecast to be near the seasonal normals, the amount of moisture available will be a limiting factor. Conditions return to a more typical summertime trade wind pattern by early next week. && .AVIATION... Breezy trade winds will persist across the island chain through Thursday. Showers and low clouds riding in on the trades will bring brief periods of MVFR conditions over windward and mauka locations. Otherwise, VFR conditions will prevail. AIRMET Tango remains in effect for moderate low-level turbulence over and downwind of island terrain due to breezy trade winds under the tradewind inversion. No other AIRMETs are in effect at this time. However, AIRMET Sierra for tempo mountain obscuration may be needed again tonight if shower coverage increases overnight. && .MARINE... High pressure to the north of the state will gradually weaken and shift eastward. A second stronger high will build to the northwest of the state over the weekend and hold into the coming week. Moderate to locally strong easterly trades will persist through Thursday then weaken slightly to the gentle to fresh range on Friday and hold through the weekend. A Small Craft Advisory (SCA) for the typically windier waters around Maui County and the Big Island will likely be dropped Thursday night, but SCA conditions may redevelop on Saturday or Sunday. An upper level low moving in from the east may bring unsettled weather to the area on Saturday and Sunday. Isolated thunderstorms are possible, especially over the western half of the state, and should be assumed to trigger locally higher winds and seas. Meanwhile, surf along east-facing shores will gradually ease over the next few days, but will pick back up on Monday as winds both local and upstream re-intensify. Along south facing shores, a small, medium- to long- period south swell will fill in tonight, peak Thursday night, then gradually ease into the weekend. Near to below average surf along south facing shores is expected into the coming week as well. A small, medium period, northwest swell is expected to fill in tonight and peak Thursday night. This will provide a small bump along north facing shores that will persist through Friday then virtually disappear over the weekend. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST Thursday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...Vaughan AVIATION...TS MARINE...Birchard/Bedal