An unseasonably strong upper-level low is expected to slide over the Hawaiian Islands on Friday, bringing pockets of heavy rain, isolated thunderstorms and a small but real chance of brief ashfall for communities downwind of Kīlauea. The volcano entered a new fountaining episode Thursday afternoon, and forecasters say the combination of plume height and shifting winds will determine whether ash stays near the summit or reaches farther afield.
What forecasters are saying
The National Weather Service has highlighted the system in a special weather statement, warning that the upper low will boost instability and moisture and raise the odds of a few heavy showers and isolated thunderstorms across the state. According to the National Weather Service, widespread heavy rain is not on the table, but pockets of heavy rain could still lead to localized ponding on roads and brief visibility drops.
Kīlauea fountaining raises ash risk
The U.S. Geological Survey's Hawaiian Volcano Observatory reports that Episode 47 began at 3:27 p.m. HST on May 14, with fountaining focused at the north vent and tephra, including fine ash, Pele's hair and other fragments, most likely falling near the summit. USGS HVO notes that tephra fall is heaviest within a few miles of the vents, while lighter ash can stay suspended and travel farther downwind. Local outlets measured fountain heights on the order of a few hundred feet during the event, which bumps up the potential for ash reports outside the immediate summit area. For an on-the-ground look at the episode as it unfolded, see Hawaii News Now.
Where ash could fall
How much ash falls, and where, will largely depend on how high the plume gets and which winds take over. If a higher plume develops, stronger southwesterly winds aloft could steer ash east or north of the summit. If activity stays lower, trade winds closer to the surface would tend to push material toward the southwest or west. That outlook is summarized by the Honolulu Star-Advertiser, which points out that the Kau and South Kona districts are among the areas most likely to see fallout if ash rides a southwest-steering pattern.
Health and preparedness tips
Public health officials and scientists caution that volcanic ash can irritate the eyes and respiratory system, so they recommend cutting down exposure when ash is present. That means keeping windows closed, running air conditioners on recirculate when possible and using N95-equivalent masks outdoors if ash is actively falling. The USGS HVO and the interagency Vog Information Dashboard provide step-by-step guidance for people with existing respiratory issues and for protecting rainwater catchment systems. County alerts will carry neighborhood-level instructions if ash or flooding threats develop.
Timing and what to watch this weekend
Forecast models show low-level moisture increasing through Saturday, which could lead to locally heavy downpours. Some forecasts indicate up to a couple of inches of rain on windward Big Island slopes by late Saturday, while the upper low is expected to drift away over the weekend and ease the thunderstorm threat. Forecasters add that even short-lived heavy showers can cause ponding in poor-drainage spots and that windward and mauka areas are likely to stay wetter than normal into early next week, according to the National Weather Service.
For real-time information, officials urge residents to follow county emergency channels and the statewide emergency page at the Hawaiʻi Emergency Management Agency, and to keep an eye on official USGS HVO products and NWS forecasts for any changes in ash or flood guidance. Conditions can turn quickly, so the advice is to lean on government advisories rather than social posts when it comes to deciding what to do.
