A weak surface trough will gradually move east to west across the islands through tonight, resulting in light winds and land/sea breeze showers. As this trough dissipates, trades will build in stronger through Monday. Trades will be on the increase Tuesday onward.
Windward and mauka showers with some limited spillover to leeward areas are ongoing across the island chain. Satellite indicates low clouds over or near the higher terrain on each island, along with high clouds streaming in from the southwest.
A weak surface trough near Maui will slowly drift westward, reaching Kauai on Sunday. Trade winds will build in behind this trough from east to west through the weekend. Wind speeds will initially be light to moderate, but will become moderate to locally breezy into early next week. This trough will keep winds weak enough to allow for land/sea-breeze showers to occasionally develop over leeward areas, even as trade winds build in and bring their typical windward and mauka focused showers.
While that is occurring at the surface, the flow aloft will change significantly. We will transition from weak troughing to our north this weekend to the rapid development of a closed ridge to our northwest by Monday. This ridge will become elongated along an east-west axis and remain with us all next week. Its presence will keep a surface ridge in place, allowing the trades to blow at least through the end of next week, and likely longer. This means mainly windward and mauka showers will hang around. There will be occasional fluctuations in available moisture throughout this period, and these will result in periods of enhanced shower activity from time to time.
Light to moderate trades gradually return tonight, becoming locally breezy today and persisting through the next several days. Expect cloud and shower activity to develop along the typical windward and mauka areas, resulting in periods of MVFR conditions. Otherwise, VFR conditions will prevail.
AIRMET Sierra remains in effect for mountain obscuration over much of the state due to lingering showers.
There may be the need for AIRMET Tango for low-level turbulence as trades gradually return.
A high pressure ridge will remain in place north of the islands with gentle to fresh trade winds for most coastal waters with periods of strong trade winds developing over the windier waters and channels near Maui and the Big Island from Sunday onward. A Small Craft Advisory may be needed for these windier waters by tonight or possibly by Sunday.
A declining medium period northwest swell and associated surf heights along north and west facing shores will slowly fade through the weekend. Small north-northwest medium period swell energy will keep surf heights on the small side through the first half of next week.
The current small south swell energy will fade through the weekend. Small pulses of background long period swell energy will keep surf heights along south facing shores above flat levels.
Surf along east facing shores will remain below normal this weekend, but will gradually increase next week as trade winds strengthen.
None.
