Forecast charts and models point to a promising looking swell for Wednesday and Thursday the 22nd-23rd from a storm that will pull together late this weekend northwest of the Hawaiian Islands. On paper, this storm has some of the ingredients we look for to produce a truly large swell at Waimea: very large significant wave heights of 40-45' are forecast to develop within 1000 miles of Oahu by Monday and Tuesday of next week. While we'd like the storm to take a better track straight at the islands, versus a sideways moving storm/fetch relative to Hawaii, the proximity of the largest seas will help to make up for that less than ideal track.
If the current forecast comes to fruition, we would see 20' surf (~35-40' faces) as the swell peaks at Waimea Wednesday afternoon and evening before backing down slowly on Thursday.
Obviously the swell producing storm has not yet pulled together and there are some discrepancies between our more trusted global wind models on the strength of the forecasted low, which would be the difference between 'normal' big wave surf (similar to what Hawaii is seeing now and in the next couple days) and 'Eddie' type surf. We'll need to closely monitor the exact strength and movement of the storm in the next few days before we can make a concrete call on exact size and timing of the swell.
The other thing to monitor will be local wind and weather conditions. At this time we are expecting unfavorable, onshore west clocking north wind during the possible peak of the swell on Wednesday, thanks to a passing front. We could also see periods of heavy rain on Wednesday. Thursday should see improved conditions as NE/ENE trades return.