Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
749 FXHW60 PHFO 301328 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 328 AM HST Sun Jun 30 2024 .SYNOPSIS... Gentle to moderate trade winds will prevail with afternoon sea breezes along terrain sheltered western slopes of each island today. Trade winds will strengthen into the moderate to breezy range as sea breezes diminish from Monday onward. Clouds and passing showers will favor the windward and mountain areas, trending higher in the overnight to early morning hours. Isolated thunderstorms are possible today near Kauai. More stable conditions are forecast from Monday onward with brief passing showers mainly forming over windward and mountain areas. && .DISCUSSION... A subtropical high pressure ridge north of the Hawaiian Islands will keep trade winds in the forecast through this week. An upper level low roughly 200 miles north of Kauai will continue to drift west today, and then weaken as it moves northward on Monday away from the region. A weak low level trough under this upper low will keep trade winds in the gentle to moderate range for one more day. Upper level forcing from this passing low will enhance shower activity over the western islands, mainly affecting windward and mountain areas in the overnight to early morning hours. Sea breezes will also develop today over terrain sheltered western slopes of each island. Large scale trades and local scale sea breeze winds will converge, producing afternoon clouds and showers over these terrain sheltered leeward locations. By Monday, the ridge will build into the islands as the upper low weakens and drifts northward away from the region. Trade winds will strengthen into the moderate to breezy range through much of next week. Stronger subsidence under this ridge will stabilize the atmosphere by lowering the trade wind thermal inversion heights and reducing cloud heights. Expect mostly brief passing showers from Monday onward as more stable conditions return to the Hawaii Region. && .AVIATION... Moderate trades expected through the rest of the weekend. SHRA and low cigs will return to windward and mauka areas. VFR should prevail, with brief periods of MVFR under heavier SHRA. No AIRMETs are currently in effect. && .MARINE... High pressure north of the state will maintain moderate to fresh trade winds today. Monday through midweek, trades are expected to strengthen back to fresh and strong levels, and a Small Craft Advisory will likely be required for the typically windy waters around Maui and the Big Island. No significant south swells are expected through this upcoming week. However, a series of small south-southwest and southeast swells will keep south facing shores from going flat. Typical mostly flat summertime conditions will continue along north facing shores. East shore surf will remain below normal on today, then trend up closer to seasonal levels early to mid this week as the trades strengthen over and upstream of the islands. && .HFO WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Bohlin AVIATION...SMW MARINE...JT