Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
959 FXHW60 PHFO 150125 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 325 PM HST Wed May 14 2025 .SYNOPSIS... Moderate to breezy trades will continue to focus showers over windward and mauka areas through next week. A developing low aloft could increase trade wind showers this weekend into early next week. && .DISCUSSION... Current radar and satellite imagery show isolated to scattered showers moving into windward areas on the breezy trades this afternoon, along with some high clouds streaming over the area from the west. These high clouds are associated with the subtropical jet to our south and are expected to stream across portions of the island chain through tomorrow before gradually clearing out this weekend as the subtropical jet shifts eastward. High pressure currently centered about 1500 miles northeast of the state will gradually sag a bit south this weekend as a series of lows traverse across the northern Pacific. The movement of this feature will have little affect on the local weather as moderate to breezy trade winds are expected to persist across the area. However, one of those northern Pacific lows will drag a front that will stall well to the northwest of Kauai and turn into a trough early next week. Model guidance suggests that the interaction of this distant front/trough with the surface high to our northeast will weaken the local pressure gradient and reduce trade wind speeds slightly on Sunday into early next week. Pockets of moisture caught up in the trades will bring periodic clouds and showers into windward and mauka areas throughout the forecast period. As a developing lower latitude upper level trough/low develops and moves over the state tomorrow into early next week, it will lower temperatures aloft slightly and increase the temperature inversion heights. While the overall instability isn`t expected to be impressive, the raised inversions will likely allow for some enhancement of trade wind showers over the weekend and into early next week as those pockets of moisture roll through. && .AVIATION... Moderate to breezy trade winds continue to prevail across the island chain through at least Thursday afternoon, steered by high pressure centered far northeast of the main Hawaiian Islands. Showers and occasional low clouds embedded within the trades will favor north through east sections of the islands throughout this period, especially during the overnight to early morning hours. While VFR flight conditions will prevail at most locations, periods of MVFR conditions will be possible within any showers that occur. AIRMET Tango remains in effect for moderate low-level turbulence downwind of island terrain. This AIRMET will likely be needed through at least Thursday. Additionally, mountain obscuration could become an issue across windward sides of the islands again later this evening and tonight. && .MARINE... A strong high will remain far northeast of the state through the week and continue to bring fresh to locally strong trade winds to all local waters. A Small Craft Advisory (SCA) for the windier waters around Maui County and the Big Island remains in effect through Thursday. Winds may ease slightly and veer toward the east-southeast over the weekend due to a weak front far northwest of the state. The current moderate period south-southwest swell will continue to decline through tonight. Expect mainly background energy along south-facing shores on Thursday. A tiny long-period south- southwest swell is possible this weekend. Otherwise, expect mainly background energy through the middle of next week. Surf along east-facing shores will remain rough and choppy the next several days due to the fresh to locally strong trades. Surf along north-facing shores will remain small with some background northwest energy moving through throughout the week and into the weekend. && .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...Farris AVIATION...Vaughan MARINE...Ahue/JVC