Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
307 FXHW60 PHFO 120650 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 850 PM HST Tue Jun 11 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... A moderate to breezy, stable, and rather dry trade wind flow remains in place this afternoon. Broad surface high located about 900 miles north of Kauai is driving the trades, and a mid-level ridge is maintaining an inversion around 5000 to 6000 feet. Minimal rain has fallen over windward slopes during the past 24 hours, and with the exception of a few showers over the Kona slopes of the Big Island, leeward areas have been dry. Some increase in trade wind showers is expected tonight and Wednesday as the trades hold near current strength. The cloud field just upwind of the island chain has changed from mostly stable stratocumulus to be more dominated by shower bearing, open celled cumulus with precipitable water in the 1.3 to 1.6 inch range. Persistent mid-level ridging will maintain stability, so rainfall totals will not be significant. Thus, expect a more typical pattern of windward rainfall to develop overnight and persist through at least Wednesday and possibly into Thursday. 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. && .AVIATION... Moderate to breezy trade winds will periodically deliver clumps of showery low clouds that will primarily focus over windward coasts and slopes, producing 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