A band of moisture will continue moving westward through the region, increasing shower coverage over the western islands today. Windward and mauka areas could see minor flooding, similar to what windward Big Island experienced yesterday. A more typical (drier but not dry) trade wind pattern will return by this evening and continue into early next week.
Early this morning, a band of moisture that produced substantial rainfall and minor flooding for portions of the Big Island yesterday has largely moved west of Maui County and the Big Island. As such, latest radar imagery shows that the majority of showers are now focused within the coastal waters off of leeward coasts. However, higher moisture content remains over the western end of the state. The early morning 12z upper air sounding from Lihue showed that the inversion height remains elevated at around 14,000 feet with around 2 inches of precipitable water, while the Hilo sounding shows that the inversion has significantly lowered to around 9,000 feet and precipitable water has reduced to around 1.5 inches.
The focus for enhanced shower coverage, with possible minor flooding, will be the western islands today. This will be followed by drier conditions statewide by this evening as the plume of moisture continues to move west of the region. A weak ridge aloft to the northeast will weaken over the next few days, and a new stronger closed upper ridge will develop to the north this weekend. This will help keep a strong surface high to our north, ensuring moderate to locally breezy trade winds continue throughout the next several days. Global models continue to indicate smaller pockets of moisture embedded within the trade flow will briefly increase trade wind shower activity from time to time through the rest of this week, but it will be difficult to time until closer to arrival. Therefore, periods of showers will continue, primarily focused along windward and mountain areas. Some days will see slightly more showers than others, and the overall pattern looks slightly wetter than normal for June. However, the risk for any significant flooding will remain low from Thursday well into next week.
Showers will dwindle this morning, with the last of any organized activity moving out of Kauai by the late morning / early afternoon hours. Drier conditions are then expected to prevail across the islands as we return to a more typical trade wind pattern. Broadly anticipating widespread VFR conditions by this afternoon.
AIRMET Sierra for mountain obscuration is in effect for windward Kauai and Oahu, with conditions expected to improve by this afternoon.
AIRMET Tango remains in effect for moderate turbulence below 8000 feet all areas of the state, and is expected to continue as we return to breezy trades across the state.
Fresh to strong easterly trades will slightly strengthen through the second half of the week as the subtropical ridge strengthens north of the islands. A Small Craft Advisory remains in effect across the typically windier channels and waters around Maui County and the Big Island. Additional marine zones may need to be added to the advisory in subsequent packages as the area of strong winds expands. Guidance suggests this pattern will persist through the weekend.
Surf along exposed south-facing shores will reach and remain just below the warning level threshold of 15 feet faces today as a long- period south-southwest swell moves through. Thereafter, a gradual downward trend is expected through the weekend. The Barbers Point buoy observed a jump to around 5 feet, 16 second swell overnight and continues to observe swell near that level early this morning. A High Surf Advisory remains in effect for south facing shores through early Thursday morning. Surf may linger around advisory thresholds during the day Thursday but will likely drop below advisory thresholds by Friday.
A small bump in surf along north-facing shores provided by a small, short-period north-northwest swell will fade today before a relatively larger north swell provides another bump to surf Thursday and Friday before easing over the weekend. Surf along east-facing shores will gradually build, with heights returning to near seasonal levels by the end of the week.
High Surf Advisory until 6 AM HST Thursday for Niihau-Kauai Leeward-Waianae Coast-Kahoolawe-Maui Leeward West-Kona-Kauai South-East Honolulu-Honolulu Metro-Ewa Plain-Molokai Leeward South-Lanai Leeward-Lanai South-Maui Central Valley South-South Maui/Upcountry-South Haleakala-Big Island South-Big Island Southeast.
Small Craft Advisory until 6 PM HST Thursday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters.
