Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
209 FXHW60 PHFO 121329 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 329 AM HST Wed Jun 12 2024 .SYNOPSIS... Broad high pressure north of the state will drive moderate to breezy trade winds for the next few days with a slight decrease expected by the weekend. Stable conditions will focus showers over windward areas, and leeward areas will be rather dry, though leeward Big Island will experience clouds and showers each afternoon and evening. && .DISCUSSION... High pressure remains situated to the north of Hawaii driving stable trade wind weather expected over the next week. Current infrared satellite and radar show scattered showers tracking over the islands from the trade wind flow. 12Z soundings show a weaker and more elevated inversion than previous ones with inversion height between 6 to 7 kft. Precipitable water values skipped a bit higher to around 1.5 to 1.6 inches. Persistent mid-level ridging will maintain stability, so rainfall totals will not be significant. Thus, expect a more typical pattern of windward rainfall to persist through midday, and possibly filling in again tonight into Thursday. Leeward areas should stay mostly dry, but upper leeward slopes will see occasional passing showers. Leeward Big Island will continue to see typical afternoon cloud build ups and showers, then clearing at night, into next week. A slight decrease in trade winds is expected heading into the weekend. The ridge to the north will be pushed southward on Friday and Saturday, then meander about 400 to 600 miles north of Kauai into early next week. With the ridge a little closer to the islands, we should experience a slight decrease in the trades. A typical distribution of trade wind showers over mainly windward slopes will prevail. A typical summertime upper low will move over the islands over the weekend and may provide a little bit of enhancement to the incoming clouds and showers. && .AVIATION... Moderate to breezy ENE trade winds will deliver clumps of showery low clouds that will primarily focus over windward coasts and slopes, producing periods of relatively short-lived MVFR VIS/CIG in SHRA. Otherwise, VFR conditions will prevail. && .MARINE... Fresh to strong easterly trades will continue through the weekend, as the surface ridge remains north of the area. This supports the Small Craft Advisory continuing for the windier channels and waters around Maui County and the Big Island each day. Surf along south facing shores will slowly ease through Thursday as the current south-southwest swell fades. Expect a mix of this the fading south-southwest swell and a small, medium-period southeast swell through Thursday. A fresh, long-period south swell is expected to arrive Thursday night into Friday, then peak late Friday into Saturday. This swell will hold through early next week as it slowly fades. Surf along north-facing shores will remain up above the summertime average (flat) through a good portion of the week as small, short-period north to north-northwest swells move through. Surf along east-facing shores will remain small and choppy over the next several days due to limited trade wind fetch upstream of the islands. && .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...Foster AVIATION...Birchard MARINE...Gibbs