Helene’s intense forecast ranks among the most extreme in hurricane history
The prediction for Helene’s evolution from a possible tropical storm to a Category 3 hurricane is noted as the quickest transition ever anticipated for a depression by the National Hurricane Center.
“They have never forecast a significant hurricane within 60 hours for a disturbance that hasn’t reached tropical storm strength,” said meteorologist Sam Lillo, referencing an analysis of historical data. “This forecast beats previous records for 36 and 48 hours from a tropical depression.”
While the National Hurricane Center did not have a specific stat on hand, as their focus was on Helene’s operational forecasting, senior hurricane specialist John Cangialosi mentioned, “it’s either the highest or among the top forecasts.”
The prediction regarding a “70-knot increase in 72 hours” made on Monday was characterized by Cangialosi as one of the most aggressive forecasts for a potential tropical system.
“This is a bold forecast for valid reasons,” he added. “We aim to stay ahead of the expected rapid intensification as it approaches Florida.”
Helene is predicted to make landfall close to the Big Bend region of Florida on Thursday evening, bringing significant wind, rain, and storm surge effects throughout the Southeast. However, the precise path remains uncertain.
The hurricane center indicated on Tuesday that the situation and timing for the storm could still change.
Insights from Computer Models on Helene’s Forecast
Various computer models used in storm forecasting show that some expect Helene to intensify significantly, predicting a steep drop in pressure that could lead to record low levels in the Gulf of Mexico.
However, Lillo cautioned that these predictions might be somewhat exaggerated. The models are facing two main obstacles: Helene’s unusual size and its disorganized state as of Tuesday afternoon.
According to Lillo, “Larger storms often take longer to strengthen, which could limit how intense they become by the time they make landfall.”
The forecasting models are having difficulty because the storm is not yet properly organized and remains uneven, with most of the intense storm clouds still positioned east of the storm’s center, according to meteorologist David Roth from the Weather Prediction Center. Helene was only officially classified as a tropical storm at 11 a.m. on Tuesday.
Roth pointed out that models can sometimes predict an “overly intense” storm under these conditions.
Fortunately, the hurricane center understands these biases present in the models. For each model predicting a very strong storm, there’s usually another one that underestimates intensity, effectively balancing each other out in the final forecast.
Upcoming Forecast for Helene
The hurricane center, alongside the National Weather Service, generally recommends that people in the storm’s potential path prepare for impacts at least one category higher than what is predicted, and currently, Helene is anticipated to hit land as a Category 3 storm with winds up to 115 mph.
Ultimately, the peak wind speeds and the lowest pressures depend on how quickly the storm’s center becomes organized now that it has formed.
“We’ve been monitoring that organization for the last 24 to 36 hours,” Lillo explained. “Once it becomes organized and tightens up, it can capitalize on the very warm temperatures in the Gulf.”
Dinah Voyles Pulver has been covering climate change and environmental issues for YSL News for over 30 years, focusing on hurricanes, tornadoes, and severe weather. You can follow her on Twitter @dinahvp.
