Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
272 FXHW60 PHFO 250139 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 339 PM HST Mon Jun 24 2024 .SYNOPSIS... Breezy trades weaken to moderate from mid-week onward as a stable trade wind pattern persists. Periodic light showers will focus over windward and mauka zones during this time. && .DISCUSSION... Sharp trade wind inversion noted on this afternoon`s soundings out of Lihue and Hilo. Combined with shallow moisture depth at the top of the boundary layer, this supports a scattered coverage of rather shallow showers that have been repsonsible for a few hundrethds of an inch of rain over select windward and mauka sites during the last 24 hours. Similar to last night, expect little more than periodic light showers over the typical favored areas. Water vapor imagery shows mid-level ridging NW of the islands centered along 170W with more subtle troughing to the east along 150W. As the week progresses, ridging will broaden and expand in coverage while the aforementioned trough cuts off, deepens, and drifts westward over the islands. This will serve to slightly weaken the inversion, but is unlikely to have a substantial impact on shower intensity or coverage. Instead, its primary impact on local sensible weather will come in the form of pressure falls that will weaken the gradient and take the edge off of the trades beginning Tuesday and continuing into the weekend. Moderate trades are therefore expected to be firmly in place during the latter half of this week. Per extended model guidance, breezy trades return as the low is reabsorbed into the westerlies early next week. && .AVIATION... Breezy to locally windy trades will begin to ease tonight through tomorrow. SHRA and brief MVFR conds should stay confined to windward/mauka locations. AIRMET Sierra remains in effect for mtn obsc for windward slopes of most islands. AIRMET Tango remains in effect for mod low-level turb over and downwind of island terrain due to the breezy trade winds. && .MARINE... Surface high pressure far north of the state will maintain fresh to locally strong easterly trades today. The Small Craft Advisory (SCA) remains in effect until Tuesday morning for the typical windier waters around Maui County and the Big Island. Trades weaken slightly Tuesday into mid-week as the high moves east- northeastward away from the islands. Surf along east-facing shores will remain rough and choppy through Tuesday, followed by a gradual downtrend during mid-week as trades ease. Surf along south facing shores will be near or slightly below seasonal norms through Tuesday night as a small, medium-period, south swell continues to move through. Nearshore buoys showed swell energy peaking in the 2-3 foot range this morning with a 12-14 second period. This swell will fade Tuesday night. Additional small, medium- to long- period south swells will return Wednesday night through the remainder of the forecast period. A small, medium-period, northwest swell will bring a tiny boost to north shore surf tonight through mid-week. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 AM HST Tuesday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...JVC AVIATION...Walsh MARINE...TS