The tight pressure gradient draped across the islands, driven by an area of strong high pressure far north of the state, will continue to produce breezy to windy trades for the remainder of the week. Showers will primarily focus along windward exposures as well as along upslope higher terrain. An increase in shower coverage and frequency is anticipated later this week, with higher rain accumulations likely occurring during the nocturnal hours.
Trade winds will remain stout across many island communities the next several days. The windiest spots will be over momentum- building areas downslope of higher terrain or in the lee of Big Island volcanoes such as Mauna Kea through the Hamakua and Kona regions, the southeastern West Maui range close to the northwest Maalaea Bay coast, exposed Kalaupapa in north Molokai, as well as leeward locales just downslope of higher terrain on Oahu and windward Kauai. Winds over these areas or those similar in wind exposure and downwind of higher terrain, have remained 25 mph sustained gusting to near 40 mph. More frequent light to occasionally moderate intensity showers will occur across many windward locations with more organized pockets of rain briefly spilling over into neighboring leeward communities. The short term rainfall forecast has the highest QPF centered on the windward upslope upper terrain of both Maui and Big Island through early Wednesday morning.
The Central Pacific upper air pattern remains stagnant as the state falls under the influence of a weak col between two relatively weak closed off lows. This synoptic setup of the islands trapped between these two weak upper lows with an anchored surface high far north of the island chain translates to little to no change for the remainder of the week. Thus, trades will remain amped up with typical trade shower behavior. Model guidance is in good phase alignment with these near-statiaonry features along with a bout of enhanced mid layer moisture advection, possibly in association with a weak tropical wave, that will begin arriving Thursday and passing over the state through Saturday. Higher-than-normal precipitable waters moving in from the east later this week signals a more wet pattern change. Rain coverage and higher intensity showers entrained within robust trades will result in higher statewide rain accumulations from Thursday into the weekend. The trade inversion will weaken, deepening a more moist boundary layer upwards to a depth of 10k ft or slightly higher. Dew points treading in the lower 70s will be felt in increased late week surface humidity. The good news is that more muggy conditions will be a bit offset by enhanced trades.
Moderate to breezy trades will continue today and bring low clouds and scattered showers to mainly windward and mountain areas. There may also be isolated spillover into leeward sites. VFR will prevail for most sites, with occasional localized MVFR mainly for windward/mountain sites for the shower activity.
AIRMET Tango remains in effect for moderate low level turbulence over and downwind of terrain for all islands. This AIRMET will likely continue through the next several days.
A strong high pressure ridge centered north of the state will help to drive fresh to strong trades across all local waters through this afternoon. A Small Craft Advisory (SCA) remains in effect for all waters through this afternoon. Will continue to monitor to see if some zones may drop out of the SCA as winds shift more easterly and drop a notch this evening.
A moderate, long period, south southwest (190-200 degrees) swell will continue to generate surf along south facing shores just below advisory levels. This swell energy will slowly lower today through the remainder of the week. Expect small surf for south facing shores leading into this weekend with mainly background energy. Another moderate, long period south southwest swell (210-220 degrees) may fill in Sunday but due to the direction of the source could be more inconsistent than this current swell.
Surf along east facing shores will remain rough and choppy through the week as fresh to strong trades hold. A small, moderate period west (280 degrees) swell is expected to arrive this weekend and linger into early next weekend. No significant swells are expected out of the north or northwest.
Small Craft Advisory until 6 PM HST this evening for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Big Island Windward Waters-Kaiwi Channel-Kauai Channel-Kauai Leeward Waters-Kauai Northwest Waters-Kauai Windward Waters- Maalaea Bay-Maui County Leeward Waters-Maui County Windward Waters-Oahu Leeward Waters-Oahu Windward Waters-Pailolo Channel.
