The subtropical ridge will slowly build back in over the Hawaiian Islands as Tropical Storm Nolo continues to drift westward away from the Hawaii Region. Higher pressure returning to the islands from will produce easterly trade winds, increasing atmospheric stability, lowering humidity levels and decreasing shower trends through the weekend. Brief passing showers will favor windward mountain areas in the overnight to early morning hours. Increasing cloud cover and shower trends may return from Monday night into Thursday morning due to a passing disturbance.
Southerly winds across the western islands last night produced bands of moderate to heavy showers affecting the islands of Niihau, Kauai, and portions of Oahu. High water levels in local streams briefly exceeded flash flood thresholds over northern Kauai triggering Flood Advisory and Flash Flood Warning issuance. No reports of flooding were received during last nights event.
Today we begin to transition back to more typical drier easterly trade wind weather just in time for the weekend. Lower humidity levels and mostly sunny skies will prevail from Saturday through Monday afternoon.
A weak disturbance in the force may bring another round of enhanced showers to all islands from Monday night into Thursday morning. Trade wind temperature inversion heights rise into the 8,000 to 10,000 foot range, which allows for scattered to numerous shower activity statewide. Northeastern to eastern windward mountain slopes would likely see the higher rainfall amounts due to easterly wind forcing in this evolving weather pattern for the middle of next week. Increased wet trade wind rainfall coverage for this time period in the latest forecast grids, with drying trends forecast by the end of next week.
Moderate southeast winds will continue today across the state as Tropical Storm Nolo moves away. Showers loosely associated with Nolo will continue to track over Kauai and Oahu today with MVFR conditions likely with brief periods of IFR conditions possible. Trade winds will push in a drier air mass tonight.
AIRMET Sierra is in effect for mountain obscuration above 2000 feet over Kauai, Oahu and above 2500 feet on Big Island, though conditions will improve over Big Island this morning. Cloud build ups likely by afternoon across Maui County and Big Island before dissipating tonight.
Moderate to fresh east to southeasterly winds will prevail across the region today as Tropical Storm Nolo lingers amongst the Northwestern Hawaiian Islands. Nolo will begin to accelerate westward away from the Hawaiian Islands today, which will diminish its influence on Hawaiian waters. Gentle to fresh east to northeast trades fill back in across the waters this weekend into early next week. A Small Craft Advisory may be needed for the typically windy channels late this weekend for locally strong trades. By mid-next week, troughing developing northwest of the islands may cause the trade winds to weaken and veer out of the southeast once again.
A moderate, medium-period west to southwest swell originating from Tropical Storm Nolo will continue for Niihau and Kauai today before quickly fading tonight. Meanwhile, a small, background south swell continues for other islands, holding surf mostly steady along south facing shores through the weekend. A new small, long-period south swell, originating from a large fetch of gale force winds southeast of New Zealand earlier this week, is forecast to arrive beginning Sunday and peak Monday through Wednesday.
Surf along north-facing shores will see a tiny bump today into tonight as a small, short-period northerly swell moves through the region. Small surf is possible early next week as a small, medium-period northwest swell arrives this weekend and peaks on Monday, followed by a slightly larger northwest swell peaking on Wednesday. Surf along east facing shores will see a slight boost and become more choppy as easterly trades build back into the region this weekend.
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