Moderate to locally breezy trade winds are expected through the weekend. An increase in moisture through Wednesday will cause showers to increase over windward and mauka areas. Limited spillover is possible to leeward areas. Drier conditions should arrive late Wednesday and remain through Saturday.
Showers, some briefly heavy, have been moving across most islands in the trades this afternoon. So far, Kauai has been the driest, but moisture is moving west and we expect them to pick up additional showers through the evening and overnight. Winds were averaging 10 to 15 mph, with gusts 20 to 30 mph in the usual spots, through mid-afternoon.
Little change to the forecast this afternoon. Models are consistent in showing a weak upper level low moving from east to west across the area just north of the islands. A weak surface trough is presently moving through the islands, leading to more showers than at this time yesterday. The strongest showers have brief heavy rain. This trough will move off to the west tomorrow.
Trade winds will continue at moderate to occasionally breezy levels through the weekend and into early next week. After the current low level trough and it's associated enhanced moisture move off to the west tomorrow, slightly drier air will move in Wednesday evening through Saturday, leading to a reduction in showers. It won't be dry enough to completely eliminate them, but they will be mainly windward and mauka through the weekend.
Moderate trade winds continue through today before strengthening tomorrow. Winds could be strong enough to warrant AIRMET Tango being issued for low level turbulence downwind of terrain. A trough currently moving through the island chain will provide an uptick in shower activity and MVFR conditions through early tomorrow morning.
AIRMET Sierra for mountain obscurations is currently in effect across windward sections of each island, and the leeward side of the Big Island. Expect clouds to clear off the leeward side of the Big Island overnight. Conditions over windward sections of each island will likely linger through tonight and gradually improve tomorrow morning.
A low-level trough passing from east to west across the Main Hawaiian Islands tonight will continue to enhance rain shower activity for all coastal and offshore waters. As the trough passes west of the islands tonight, in combination with a strengthening subtropical ridge to the north, trade winds are forecast to increase, prompting the issuance of a Small Craft Advisory (SCA) for the typically windier waters and channels near Maui and the Big Island. Winds will remain moderate to locally strong, which will likely require the SCA to remain in effect through the weekend.
A series of small to moderate, medium to long period south and southeast swells will keep surf along south facing shores elevated through the week. A small, medium period south swell will continue to fade through Wednesday. The forerunners of the next long period south swell will begin to arrive in the islands by Wednesday morning, and then build into Wednesday night, peaking on Thursday with head high to overhead surf heights at most exposed south shore surf breaks.
Surf along east facing shores will gradually build through Wednesday and then hold into the weekend as trade winds strengthen. West facing shores will remain on the small side with a slight south swell wrap. Surf heights along north facing shores experienced a bump today with a bit of north swell energy, though this is forecast to fade tonight returning surf to fairly flat conditions. Another tiny bump in surf is possible Wednesday night into Thursday with a little bit of west-northwest swell energy arriving.
Small Craft Advisory until 6 AM HST Thursday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Maalaea Bay-Pailolo Channel.
