Hurricane Lane is currently a powerful category 4 hurricane with maximum sustained winds of around 150 mph, making it a borderline category 5 storm. Earlier model projections had Lane skirting to the south of the Hawaiian islands, but over time, model guidance has begun to trend northward, increasing the likelihood that Hawaii with either be indirectly or directly impacted by Lane.
When a hurricane strengthens, the wind flow in the mid and upper-levels of the atmosphere becomes increasingly important, since those winds have a strong influence on the steering of the storm. Over the last several days, Lane has remained positioned to the south of a mid-level high pressure system that has extended as far west as the Hawaiian islands. Given that the flow around a high pressure feature in the Northern Hemisphere is clockwise and given Lane’s previous position relative to the high, the hurricane has generally been on a westward track. The issue is that as Lane continues westward, the high is going to weaken over/near Hawaii, which will eventually put Lane on the western periphery of that feature. This means that Lane will likely begin to make a northwestward turn towards the Big Island in a day or so.
There is generally a consensus between the operational European and GFS models that Hurricane Lane is going to begin making a turn northwestward towards Hawaii by mid-week. The GFS projects that the Big Island will be directly impacted by the storm, while the European model brings the storm a bit farther westward and directly has it impacting the smaller Hawaiian islands to the west.
Hurricane Lane is currently in an environment with low vertical wind shear and sufficiently warm sea surface temperatures. This has played a significant role in Lane’s recent strengthening. Lane is expected to encounter strengthening southwesterly wind shear as it approaches the islands, but the issue is that this probably won’t occur until Lane is already impacting the islands. The low-level flow is generally from east-to-west, which would be much more influential on Lane’s motion if it were weaker. In this scenario, Lane would be steered more westward. However, as long as Lane remains adequately strong which is now the most likely scenario, it will begin moving dangerously close to the islands later this week.
The Central Pacific Hurricane Center is going with a consensus between the GFS and European models in their latest track projection and has issued hurricane watches for the eastern half of the islands. Note that the Big Island, along with several of the smaller islands to the west are now in the cone of uncertainty. The forecast will have to be fine-tuned over the next couple of days, as far as whether or not there will be an actual landfall or where that could occur. However, given the size of Lane, impacts will most likely occur to Hawaii even if Lane does not technically make landfall on any of the islands. Once Lane begins to interact with Hawaii’s mountainous terrain and becomes more heavily influenced by increasing vertical wind shear, it will begin to weaken and steer westward. Since Lane will gain a lot of latitude over the next several days, this increases the odds that a large part of the island will at least be impacted, to some extent.
If you are planning to be in Hawaii this week, please continue to monitor these forecasts closely. If you have plans to travel to the island and can change those plans, I encourage you to keep an eye on the latest forecasts through today and tomorrow and change plans, if necessary. Please continue to follow Firsthand Weather on Facebook and Twitter, as we will be continuously posting updates on social media.