The upper level low that brought all of the showers the last several days is now heading out westbound, but as it does, it is pulling behind it deep tropical moisture. This moisture plume will impact Maui County and Hawaii Island tonight into Tuesday. This area of enhanced moisture to our east will be the main weather player for the next couple of days for the eastern islands. That may mean some thunderstorms in the forecast for Hawaii Island and Maui. Stay tuned. It all depends how these ingredients come together during this time period.
Southeasterly winds will pull in deeper tropical moisture over the eastern islands next week Tuesday and Wednesday with additional rounds of unsettled weather. A Flash Flood Watch is in effect from tonight through Tuesday night for the eastern end. Temperatures aloft will be cold enough for heavy snow showers on the highest summits of Mauna Kea and Mauna Loa where a Winter Storm Warning is in effect beginning tonight.
As for the western end of the islands, there will be some pop up showers but overall the atmosphere over Oahu and Kauai will not be as unstable nor moist therefore less heavy rain is expected there. Showers would tend to favor interior and mauka areas but other areas could see some shower activity as well on Oahu and Kauai. Most of these showers are expected to be on the lighter side.
Then on Wednesday, the upper level low will continue to pull north and the tropical moisture becomes less of an influence. The one exception may be Hawaii Island, due to a weather disturbance parked off of the island that could potentially keep things fairly unstable there. If that set up holds true, then more pop up storms are possible for Hawaii Island on Wednesday.
Then beyond Thursday, an area of high pressure is going to dominate the forecast bringing back the trade winds to the islands.
The NWS has a High surf advisory up for east shores. There is no longer a warning. The current north-northeast swell will become more northerly and gradually lower through Tuesday. The current northwest swell will hold through Tuesday then lower to small levels Wednesday through the weekend. A moderate short-period east swell is expected to build on Tuesday and may bring advisory level surf to east facing shores Tuesday night through Thursday. Surf will remain small along south facing shores through the weekend.