Hawaii Issues Hurricane Warning for Big Island as Lala Strengthens to 60 Mph

Q: Could the Big Island's massive volcanoes unexpectedly trap Hurricane Lala, unleashing catastrophic flooding instead of breaking the storm apart?

No. The Big Island’s volcanoes are more likely to disrupt and distort Lala than “trap” it in place, but they can greatly increase rainfall and flood danger while the storm slows nearby. Forecasters already expect some slowdown as Lala interacts with Hawaiʻi Island’s terrain. That does not mean the storm would become stuck against the mountains in a literal sense. The larger steering pattern — a strong ridge north of the islands — is still expected to keep pushing Lala west-northwest, with the center passing near South Point and then south of the rest of the state. Terrain can cause wobbles, brief stalls or structural disruption, especially on the lee side, but not an indefinite lockup. The bigger concern is that the volcanoes can wring out much more rain. Meteorologists have warned of orographic enhancement, where moist tropical air is forced up the slopes of Mauna Loa and Mauna Kea. That can intensify rainfall over windward and upslope areas, especially around Hilo, Volcano and the southeast-facing slopes. Forecast totals of 8 to 12 inches, with up to 25 inches on the Big Island, reflect that risk. So the disaster scenario is not the mountains pinning the cyclone in one spot for days. It is a storm moving slowly enough, and close enough, for terrain to concentrate extreme rain over the same areas, causing flash flooding, mudslides and rapidly rising streams. In past Hawaii storms, that setup has produced major flooding even when the storm center stayed offshore.

3 articles · Updated · PBS NewsHour · Aug 14

Hawaii Island is under a Hurricane Warning as Tropical Storm Lala, with 60 mph sustained winds, is forecast to reach hurricane strength before nearing the Big Island on Saturday morning.
At 5 p.m. Thursday, Lala was 555 miles east-southeast of Hilo and moving west-northwest at 12 mph, with forecasters keeping its track largely unchanged toward South Point.
Maui County is under a Tropical Storm Watch, with tropical-storm conditions possible by late Saturday as the storm passes south of the rest of the islands through Sunday morning.
Rainfall of 8 to 12 inches is expected across Maui and the Big Island, with isolated totals up to 25 inches on the Big Island, raising the risk of life-threatening flooding and mudslides.
Storm surge of 1 to 3 feet and building surf on east-facing shores are expected this weekend, adding coastal flooding, dangerous waves and rip-current threats to the wind and rain hazards.