Moderate to breezy trade winds will strengthen through the week and deliver periodic showers to windward and mountain areas.
A strengthening high pressure system north of the Hawaiian Islands will increase trade winds with wind speeds peaking by Thursday afternoon. A band of unsettled clouds are riding into the islands on the trade winds tonight. Expect brief MVFR conditions mainly along windward mountain slopes through the early morning hours. Weather conditions will show improving trends after 9 AM HST.
AIRMET Sierra for mountain obscuration was expanded tonight to include both Kauai and the Big Island. These conditions will likely diminish shortly after sunrise.
AIRMET Tango remains in effect for low level turbulence driven by the strengthening trade winds.
High pressure far north of the state will maintain fresh to locally strong trades through the weekend, for which a Small Craft Advisory (SCA) remains in effect for the typical windier channels and waters around Maui and the Big Island. Trades are expected to strengthen another notch Thursday into Friday, which has prompted an expansion of the SCA to all Hawaiian Waters for Thursday and Thursday night. Widespread fresh to strong winds are expected during this time with near gales possible for the windier waters around Maui County and the Big Island. The strong high to the north is expected to eventually shift westward and weaken some, which should allow the trade winds to weaken a notch around Sunday evening. Trends in the strength and direction of winds early next week become less clear as a result of the uncertain track of a weakening Hurricane Fausto (forecast to become a tropical storm by Monday) in the central Pacific.
Offshore and nearshore buoys are showing an increase in energy over 20 second periods as forerunners from the next notable incoming south swell slowly fill in tonight. A High Surf Advisory (HSA) has been issued from 6 am Thursday as surf is expected to increase to advisory levels through the day. There is also potential to approach warning levels late Thursday into Friday as the swell peaks. Over the weekend, reinforcing long-period energy may allow advisory level surf to persist and may require an extension of the HSA.
Surf along east-facing shores will remain slightly below seasonal levels through the evening due to the weaker trades upstream of the islands. The Hilo buoy continues to show a small, medium- period east swell this evening, which was likely generated by former TC Elida. Stronger trade winds will also support an increase of short-period energy heading into Thursday and Friday. This weekend, larger surf generated by Hurricane Fausto is possible and could bring advisory level surf along east facing shores by late Sunday into early next week.
Surf along north-facing shores will remain at flat to tiny levels through the weekend.
High Surf Advisory from 6 AM Thursday to 6 AM HST Friday for Big Island South-Big Island Southeast-East Honolulu-Ewa Plain- Honolulu Metro-Kahoolawe-Kauai South-Kauai Southwest-Kona-Lanai Leeward-Lanai South-Maui Central Valley South-Maui Leeward West- Molokai Leeward South-Niihau-South Haleakala-South Maui/Upcountry-Waianae Coast.
Small Craft Advisory from 6 AM Thursday to 6 AM HST Friday for Big Island Windward Waters-Kaiwi Channel-Kauai Channel-Kauai Leeward Waters-Kauai Northwest Waters-Kauai Windward Waters-Maui County Leeward Waters-Maui County Windward Waters-Oahu Leeward Waters-Oahu Windward Waters.
Small Craft Advisory until 6 AM HST Friday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Maalaea Bay-Pailolo Channel.
