Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
538 FXHW60 PHFO 230134 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 334 PM HST Wed May 22 2024 .SYNOPSIS... Gentle to locally breezy east to southeast winds will continue to produce clouds and showers along windward and mauka areas, with a few clouds and showers that developed over sheltered interior and leeward sections of the state tapering off later this evening. Moderate to breezy easterly trade winds will spread over the state tonight into Thursday and linger through the first half of next week. Clouds and showers will favor typical windward and mauka areas. && .DISCUSSION... The latest surface analysis shows the trough of low pressure has moved westward since this morning and is now roughly 500 miles west- northwest of Kauai. The high northeast of the state has also moved westward since this morning and is now centered around 1400 miles north- northeast of Honolulu. Satellite imagery shows clouds persisting along windward locations and some clouds that have developed along leeward locations due to seabreezes. Radar shows some showers have developed over the Koolau range and interior Oahu this afternoon but has tapered off slightly. The USGS Punaluu Stream gauge record roughly a third of an inch of rainfall during this time. Otherwise relatively limited rainfall elsewhere. Little change in the forecast philosophy. Moderate to locally breezy east to southeast winds will transition to more easterly tonight into Thursday as the high pressure system continues to slowly shift north of the state through Friday. Then a series of reinforcing highs will build to our north through the first half of next week maintaining moderate to breezy easterly trade winds into much of next week. Guidance also shows drier air filtering into the region over the next couple of days with dewpoints returning to near normal by Friday. Weak upper level troughing will give way to ridging allowing for a more dry and stable trade wind pattern to develop through the weekend. Expect windward and mauka showers to increase in intensity and coverage during the overnight and early morning hours, with a few of these showers briefly spilling over into leeward areas. This pattern should hold through the first half of next week. && .AVIATION... Moderate to locally breezy east to southeast winds will strengthen slightly heading into Thursday and transition to a more typical trade wind pattern, and VFR conditions will generally prevail. However, moisture riding in on the trades will focus clouds and a few showers over windward areas, particularly over the eastern end of the state where the greatest moisture will reside. MVFR conditions will be possible in any showers that develop. Unlike today, winds will not be light enough to see much sea breeze activity tomorrow. AIRMET Sierra for mountain obscuration remains in effect for windward areas of Maui and the Big Island. Satellite imagery continues to show some more moisture upstream, so this AIRMET may be needed through tonight. && .MARINE... Strong high pressure remains nearly stationary far northeast of the state, while a trough over 400 nm northwest of Kauai drifts westward. As a result, fresh to strong easterly trade winds Big Island and and Maui waters veer out of the east-southeast around Oahu and Kauai. Due to the slightly veered flow, a Small Craft Advisory (SCA) is in effect for all waters around the Big Island, waters north of Maui, and the Pailolo Channel. As the trough drifts westward, expect the stronger easterly trades winds to spread to Oahu and Kauai on Thursday, when Maalaea Bay will be added to the SCA. Fresh to locally strong easterly trade winds will persist into the weekend, and the SCA may be limited to the typically windy waters around the Big Island and Maui Thursday night or Friday. A decrease in winds is possible on Monday. The current south swell has declined to just below 2 feet at 12 to 13 seconds at the local PacIOOS buoys this afternoon and will fade out on Thursday. Surf along south and exposed west shores is dropping below seasonal average this afternoon, and with only small inconsistent pulses of southwest swell due for the rest of the week, small surf will prevail. The next significant south- southwest swell will be nearly a week and a half away. The windward PacIOOS buoys are showing trade wind generated seas of about 6 to 7 feet at 8 to 9 seconds this afternoon, which is producing rough east shore surf around the seasonal average. Surf along east facing shores will be near current levels or slightly higher during the next two days, with a slight decrease possible this weekend. Surf along north shores will remain very small with a slight bump possible Sunday and Monday. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 AM HST Friday for Maui County Windward Waters-Pailolo Channel-Alenuihaha Channel-Big Island Windward Waters-Big Island Leeward Waters-Big Island Southeast Waters. Small Craft Advisory from 6 AM Thursday to 6 AM HST Friday for Maalaea Bay. && $$ DISCUSSION...Almanza AVIATION...Farris MARINE...Wroe