Strong trades develop this weekend as Tropical Storm Moke moves from east to west, south of the islands. This system will deliver periods of rainfall to all islands, but heaviest along windward and southeast slopes of the Big Island. A Flood Watch remains in effect for the Big Island.
Tonight into Saturday, trade winds will fill back in, gradually strengthening across the island chain from east to west becoming locally strong by the afternoon. AIRMET Tango will likely be needed for low level turbulence downwind of island terrain.
While occasional pockets of MVFR conditions will be possible within passing showers along windward and mauka locations, VFR conditions are expected to prevail through Saturday.
A trough in the northwest offshore waters will move west as trade winds have begun to fill in across the coastal waters from east to west. A Small Craft Advisory (SCA) has been issued through Saturday afternoon for the windier waters and channels around Maui County and Big Island. The SCA may need to be extended into western waters this weekend as trades strengthen in response to Tropical Storm Moke passing south of the state. Seas greater than 10 feet will may occur over the eastern half of the coastal waters.
Tropical storm conditions are expected Saturday night into Sunday across the southern offshore waters. Thus, a Tropical Storm Warning is in effect for these waters this weekend.
Surf along south-facing shores will remain elevated through the weekend. Another reinforcing south swell is expected over the weekend which should boost surf to near the summer averages this weekend. A series of south swells next week, with above average surf during the second half of next week, may potentially increase surf to advisory levels.
Surf along east-facing shores remains below average tonight then is expected to build this weekend per strengthening trades. Surf along east and south-facing shores will be compounded by a southeast swell generated by Tropical Storm Moke that will build in through Sunday and then become south to southwesterly through early next week. This short period captured fetch from TS Moke could cause surf to approach advisory levels along the east-facing shores of Big Island Saturday night into Sunday. Moke's wind field is forecast to be relatively small and, with potential shifts in forecast tracks, forecast confidence for Big Island east-facing shore advisory-level surf is low.
North-facing shores will remain tiny through tonight. Small, medium to long period west to north swell originating from Hurricane Lala will arrive this weekend.
Flood Watch from late Saturday night through Monday afternoon for Big Island East-Big Island Interior-Big Island North-Big Island South-Big Island Southeast-Big Island Summits-Kohala-Kona.
Small Craft Advisory until 6 PM HST Saturday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Maalaea Bay-Pailolo Channel.
