Overall most of the low pressure systems and frontal systems in the Pacific are out of reach for the Hawaiian Islands, as most of them have been moving away from the islands. That being said, there is a Low pressure system and a cold front that needs to be addressed.
A low pressure system is an area where the air is less dense compared to the standard atmosphere pressure which is accompanied by winds that circle around the area in a clockwise fashion. A cold front is a transition zone where cold air overtakes warm air.
The Ocean Prediction Center reported that a cold front that is about 200 miles north of the state, and a Low pressure system right behind it.
This low pressure system is pushing the front towards the south-southwest which has the potential to hit the islands. As the winds near the Hawaiian islands are pointing towards the southwest, there is a significant chance of cold air transported to the islands. This is what we call Cold Air Advection. Cold fronts also bring the possibility of thunderstorms as the warm air that is being overtaken by the cold air mass will be forced upwards, which causes cloud formation and electrification within those clouds.
As that cold front moves closer and closer towards the Hawaiian islands, the precipitable water, or the amount of precipitation if all of the water vapor was precipitation, increases from 28mm to 54mm. Those areas with 54mm of precipitable water is already experiencing at least 5mm of rainfall, and is experiencing increased buoyancy (increasing the probability of Thunderstorms).
Monday: Mostly Cloudy with PM Rain Showers with possible rumbles of thunder. High of Mid to lower eighties, and a low of low to mid 70s with Southwest Winds from 10 to 15 mph. 90% Chance of precipitation.
Tuesday: Partially Cloudy with Scattered AM rain showers. High of Mid to lower eighties and a low of low to mid 70s, with Southwest Winds from 10 to 15 mph. 40% chance of precipitation
Wednesday: Mostly Sunny. High of Mid to lower eighties, and a low of low to mid 70s with Southwest Winds from 15 to 20 mph. 20% Chance of precipitation
Thursday: Mostly Sunny. High of Mid to lower eighties, and a low of low to mid 70s with Southwest Winds from 15 to 20 mph. 10% chance of precipitation
Friday: Mostly Sunny. High of Mid to lower eighties, and a low of low to mid 70s with Southwest Winds from 10 to 15 mph. 20% chance of precipitation