Moderate to locally breezy north-northeast trade winds expected this evening with some higher gusts over leeward areas. Scattered showers over windward and mauka areas are possible this afternoon with a passing trough. Drier and cooler air will fill in state wide by Sunday with scattered showers returning at the start of the work week.
Satellite and radar imagery show scattered clouds with some showers mostly along windward and mauka areas ongoing this afternoon. For the rest of today we should see showers gradually decrease west to east as a drier airmass builds in over the state. High pressure far north of the state should gradually strengthen our north-northeast trade winds this evening with gusty winds expected over leeward areas. Gusty winds 40 mph over select leeward areas are possible. Elected not to issue a Wind Advisory for leeward areas for the time being as observations are still below advisory thersholds. Winds will be closely monitored to see if winds reach Wind Advisory thresholds this evening and a Wind Advisory may be needed.
Sunday looks to be a windy mostly dry day. Some scattered showers will be possible over windward Big Island especially in the morning hours.
A cold upper level low will develop northeast of the state through Wednesday. While temperatures aloft will be cold and unstable, we will continue to remain on the dry side of the upper level low. While heavy showers are not expected, we should see scattered showers moving in with the trade winds especially over windward and mauka areas. Trade winds will gradually decrease throughout the first half of next week as the high weakens to our north. Trade winds should lower to moderate speeds towards the second half of next week.
A weak trough of low pressure is enhancing windward showers on the Big Island, and should continue to do so into tonight. This is bringing periodic MVFR conditions and mountain obscuration. Mountain obscuration is also occurring on Molokai, Lanai, and Maui. Winds were moderate this afternoon, and are expected to be moderate through tomorrow, although some guidance shows winds weakening somewhat tomorrow.
AIRMET Sierra for mountain obscuration remains in effect for Molokai, Lanai, and Maui, and for N through E sections of the Big Island. This may be continued through tonight.
A northwest swell will decline tonight. A new, short period north northeast swell will build in Sunday pushing surf heights along north and east facing shores to near advisory by the end of the day. Surf heights may reach advisory levels along both shorelines Sunday night into Monday before the swell begins to fade through the rest of the week.
Along south-facing shores, small background pulses will keep surf heights above flat conditions through early next week. Surf along west facing shores will be mainly small through the week.
A low pressure system northeast of the islands and a high pressure system to the far northwest of the Hawaii region will keep fresh to strong northeasterly trade winds into early next week. The low will weaken by midweek allowing winds to taper slightly. A Small Craft Advisory is posted for all Hawaiian coastal waters due to a combination of strong trade winds and seas from the incoming north northeast swell.
Small Craft Advisory until 6 PM HST Sunday for Kauai Northwest Waters-Kauai Leeward Waters-Kauai Channel-Oahu Leeward Waters- Kaiwi Channel-Maui County Leeward Waters-Maalaea Bay-Pailolo Channel-Alenuihaha Channel-Big Island Windward Waters-Big Island Leeward Waters-Big Island Southeast Waters.
Small Craft Advisory from 6 AM to 6 PM HST Sunday for Kauai Windward Waters-Oahu Windward Waters-Maui County Windward Waters.
