Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
546 FXHW60 PHFO 180657 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 857 PM HST Mon Jun 17 2024 .SYNOPSIS... Surface high pressure north of the state will maintain breezy trade winds through Tuesday, with trades strengthening into the breezy to strong range Wednesday through the weekend. Fairly typical windward and mauka-focused shower activity is expected through much of the week. Remnants of an old frontal boundary could increase windward shower activity late Friday into Saturday. && .DISCUSSION... A weak upper-level low, centered a couple hundred miles southeast of Oahu, is sending high clouds across the eastern half of the state this evening, which made for a beautiful sunset visible on the Mauna Kea CFHT webcams. Expecting a fairly typical trade weather pattern through Tuesday night, with breezy wind speeds and passing showers focused on the windward and mauka areas. Shower activity will be slightly higher than usual, due to the upper low, with some moderate showers possible over windward areas at times, mainly during the overnight and early morning hours. As the upper-level low gradually moves westward over the next few days, we should see drier conditions with lower inversions around mid-week. Beginning Wednesday into Thursday, the surface high centered far north of the state will strengthen, increasing the trade wind speeds into the breezy to strong range during the second half of the week and into the weekend. The global models are showing an area of enhanced moisture, associated with an old frontal boundary, riding in on the trades toward the end of this week. This could produce enhanced windward showers late Friday into Saturday. && .AVIATION... Breezy trades will continue, with SHRA and low cigs favoring windward and mauka locations. Periods of MVFR conds are possible in any SHRA. Otherwise, VFR conditions should prevail. AIRMET Sierra will go into effect for mtn obsc for windward portions of all islands at 09Z. AIRMET Tango is in effect for mod turb between 140 and FL300 from the Big Island up through Molokai. && .MARINE... Fresh to strong easterly trades will strengthen late Tuesday through the second half of the week as the surface ridge builds north of the state. This will result in the Small Craft Advisory (SCA) expanding up the island chain from the typically windier waters around Maui County and the Big Island. Seas will quickly respond and build to the advisory level across the exposed channels and waters near South Point beginning around Wednesday. Surf along south-facing shores continues to ease this evening, and that trend will persist through Tuesday. Expect mainly background south to south-southwest pulses moving through until Friday. A slight upward trend is possible by the end of the weekend from a small, long-period south swell. Guidance shows this arriving Saturday night into Sunday, then lingering into early next week. Surf along east-facing shores will hold around average through the day Tuesday, then gradually trend up through the second half of the week due to the aforementioned trades strengthening locally and upstream of the islands over the eastern Pacific. Surf along north-facing shores trended up today due to a small northwest swell moving through. That should linger into Tuesday before returning to typical summertime (flat) levels. As the trades increase, some northern exposures could see a gradual increase later this week. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST Tuesday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...TS AVIATION...SMW MARINE...Gibbs