Hurricane Ida's strength may have seemed surprising. But not to forecasters.

As Hurricane Ida rocketed into a powerhouse Category 4 storm barreling toward the Louisiana coast, it came as little surprise.

Forecasters had predicted the path of the storm for several days – as well as the potential for the system to intensify – and the track accurately followed the predicted course.

But in New Orleans, Mayor LaToya Cantrell said the lightning-speed growth of the storm prevented mandatory evacuations within the city. "We don’t have the time,” she said Saturday.

Did Ida's more-rapid-than-expected-growth catch meteorologists off guard?

Experts said no: The accuracy of the forecast from the National Hurricane Center was spot-on and the best possible under the limits of science.

"The NHC was explicitly calling for rapid intensification right from the time of storm formation and had Ida pegged as a Category 4 about 36 hours prior to landfall," Colorado State University hurricane researcher Phil Klotzbach told USA TODAY.

"Rapid intensification" is a process in which a storm undergoes accelerated growth: The phenomenon is typically defined to be a tropical cyclone intensifying by at least 35 mph in a 24-hour period.

Latest news: Rescue boats fan out across Louisiana amid Ida flooding. Power could be out 6 weeks for some.

"Rapid intensification occurs when a tropical storm or hurricane encounters an extremely conducive environment," Klotzbach said. "Typically, this environment consists of very warm water, low vertical wind shear and high levels of midlevel moisture."

Ida exploded in intensity before landfall after moving over the exceptionally warm Gulf waters, going from 85 mph to 150 mph in 20 hours, easily exceeding the official threshold for intensification. The storm smashed into the Louisiana coast Sunday with winds of 150 mph, tying it for the fifth-strongest hurricane to hit the U.S. mainland on record.

University of Miami hurricane researcher Brian McNoldy lauded the forecast even from the very first predictions. "In the first forecast made for Tropical Depression Nine (on Thursday), the NHC made the exceptional call to include rapid intensification in their forecast," he said.

"That forecast was shockingly confident, and something we almost never see," McNoldy said.

River flows backward: Hurricane Ida was so powerful it reversed the flow of the Mississippi River

James Franklin, a part-time contractor at the NHC with the Hurricane Forecast Improvement Project, said, "60 hours of lead time advertising a major hurricane at landfall is admirable."

Correctly forecasting intensity was an issue that he and others have worked on for decades, he said. It seems "pretty good" that the hurricane center was able to say nearly three days in advance that Ida would be a major hurricane at landfall, he said.

"Forecasting the exact magnitude of rapid intensification is always a tricky business," Klotzbach said. "Ida was in quite a conducive environment after it passed over the western part of Cuba, but it didn't really intensify much until late Saturday. Then the bottom dropped out of the storm."

McNoldy said Ida was a tough call. "Each subsequent forecast kept raising the bar as Ida continued to take full advantage of ideal environmental conditions in the Gulf," McNoldy said. "But by Friday afternoon's advisory, (the NHC) forecast was for a Category 4 hurricane in the northern Gulf, and it correctly remained in the forecasts until the end."

What role does climate change play in rapid intensification? Jeff Masters, a former hurricane hunter meteorologist at the National Oceanic and Atmospheric Administration and founder of the Weather Underground, told USA TODAY that global warming is having consequences. "Climate change is causing more rapid intensification of Atlantic hurricanes, and Ida was one of the top 5 fastest-intensifying hurricanes on record before a U.S. landfall."

Updated forecast: As hurricane season enters its peak, NOAA's updated forecast calls for even more storms: 21 named systems

Though scientists expect storms' intensification rates to accelerate with global warming, that may not be easy for forecasters to map. "Given the limitations of hurricane data, it may be some time before we can unequivocally pick out that signal in the actual observations," Masters said.

For areas weighing evacuations, uncertainty about the exact intensity of storms could loom large. "It takes longer to evacuate a city than it takes to build a destructive hurricane," Kelly Hereid, a climate scientist at Liberty Mutual, tweeted.

Contributing: Dinah Pulver, USA TODAY; The Associated Press

This article originally appeared on USA TODAY: Forecast for Hurricane Ida was accurate, despite rapid intensification