Moderate to breezy trade winds will increase through the week and deliver showers to windward and mountain areas.
Current radar and satellite imagery this morning show isolated to scattered showers passing through windward and mountain areas of all islands. This summer time trade wind shower pattern should continue through at least the weekend with minor fluctuations in rainfall as pockets of slightly drier and wetter air move through with the trade winds. A stable ridge overhead will keep most of these showers on the lighter side.
The trade winds will be supported by building high pressure to the north, becoming breezy to locally strong today through the remainder of the week. A weakening TC Fausto then approaches the area early next week with guidance generally tracking the system near or just north of the islands during the mid- week period. So far it is too early to know exact details on how this storm will effect our weather, as it will be heavily dependent on the eventual track and intensity.
Light shower activity will continue to wane through the morning, however periodic MVFR remains possible across windward sites so long as shower activity persists. Moderate trades are expected through the forecast period, with skies partially clearing across the islands by the afternoon.
AIRMET Sierra is in effect for the windward Kauai, Oahu, and Maui due to low clouds from ongoing showers. Conditions, however, are expected to improve by the afternoon.
High pressure far northeast of the state will maintain fresh to locally strong trades through tonight. 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 as a 1036 mb high develops far north of the state. 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 SCA will be expanded to other area waters as the trades pick up later this week. 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.
The current medium-period south-southeast swell producing above average surf along south-facing shores will continue to gradually fade over the next few days. Forerunners from the next notable incoming south swell will slowly fill in throughout the day today into Thursday and peak late Thursday into Friday with surf heights above advisory thresholds. Offshore buoys are showing an increase in 23 second energy this morning, so we should see some very long-period energy slowly fill in today. Surf should reach High Surf Advisory (HSA) thresholds by Thursday with surf heights approaching warning levels during its peak. Over the weekend, reinforcing long-period swell energy may allow HSA conditions to persist through the weekend.
Surf along east-facing shores will gradually increase over the next several days as the trades strengthen. The Hilo buoy continues to show a small, medium- period east swell this morning, which was likely generated by former TC Elida. This swell should peak today into tonight with near seasonal level surf. This weekend, larger surf generated by Hurricane Fausto is possible and could bring advisory level surf along east facing shores.
Surf along north-facing shores will remain at flat to tiny levels through the weekend.
Small Craft Advisory until 6 AM HST Thursday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Maalaea Bay-Pailolo Channel.
