Forecast: Possible heavy rain and thunderstorms moving in

Friday morning forecast

There’s a chance of some heavy showers and even a thunderstorm or two ending the work week, with a flash flood watch for the state until 12 midnight Saturday night.

What's happening is that a trough of low pressure will be moving from west to east. That's going to draw up a pool of moisture northward over the islands. Combine that with instability from the trough and you have the ingredients for heavy rain and thunderstorms.

It gets a bit interesting into the weekend. A cold front will be moving in from the northwest on Saturday and then stall out over Oahu, while the trough lingers near the Big Island, so there will be a higher potential for rain over the far west and east ends of the state.

At the beach, a high surf advisory remains posted for south-facing shores for 5 to 8 foot waves. That swell will lower this evening. Swells on other shores are also on the way down. Surf will remain pretty quiet through the weekend until a moderate north-northwest swell arrives sometime Sunday. An even larger northwest swell is expected Monday night that could bring advisory level surf for north and west shores.

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