19 Apr 2023 | 10:13 AM UTC
US: Adverse weather forecast across much of Hawaii through at least April 20
Severe weather forecast across much of Hawaii, US, through at least April 20. Possible flooding and associated disruptions.
Event
A cold front is forecast to bring thunderstorms accompanied by heavy downpours, strong winds, lightning, and possible hail storms across much of Hawaii through at least April 20. The front is expected to move over the state April 19 before stalling near Hawaii Island April 20 and dissipating by April 21. Heavy rainfall may generate flooding in low-lying areas and landslides on unstable slopes. As of late April 18, the National Weather Service (NWS) has issued flash flood warnings across Hawaii Island and flood watches across much of the rest of Hawaii. Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.
Hazardous Conditions
Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites located downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where the soil has become saturated by heavy rainfall.
Authorities could issue mandatory evacuation orders for flood-prone communities over the coming days. Disruptions to electricity and telecommunications services are possible where significant flooding or landslides impact utility networks.
Transport
Flooding has resulted in the closure of Highway 11 near Kawa Flats as of late April 18. Floodwaters and debris flows may render further bridges or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters.
Severe weather could also trigger flight delays and cancellations at airports across Hawaii. Authorities may temporarily suspend port operations or close beach fronts if strong winds trigger hazardous sea conditions.
Localized business disruptions may occur in low-lying areas; some businesses might not operate at full capacity because of flood damage to facilities, possible evacuations, and some employees' inability to reach work sites.
Advice
Monitor local media for weather updates and related advisories. Confirm all transport reservations and business appointments before travel. Make allowances for localized travel delays and potential supply chain disruptions where flooding has been forecast. Do not drive on flooded roads. Charge battery-powered devices in the case of prolonged electricity outages.
