What category is Hurricane Milton? Florida has bigger worries than that.

Hurricane Milton, now barreling toward an expected landfall on Florida's west coast late Wednesday into early Thursday, has been rapidly upgraded and downgraded in the past few days as meteorologists grapple with the storm's destructive potential.

Its wind speeds have been ranked as high as a Category 5 hurricane. But as the storm weakens slightly to a Category 4 Wednesday morning, forecasters say that ranking doesn't capture the storm's true potential.

The scale that ranks hurricanes – officially known as the Saffir-Simpson Hurricane Wind Scale – is a rating based on maximum sustained wind speed, which ranges from 74 to 157 mph, or higher. The scale does not take into account potentially deadly hurricane hazards such as storm surge, rainfall, river flooding and tornadoes.

In Milton's case, experts are focusing their concerns on the storm's growing size and potential for massive storm surge along populated areas — two of the things that don't factor into category rankings. (The situation was slightly different with Helene, where the storm's winds were a bigger concern as it made landfall in a less populated area with lots of trees and vulnerable structures.)

"Milton has the potential to be one of the most destructive hurricanes on record for west-central Florida," the National Hurricane Center warned.

Regardless of the category, a life-threatening and highly destructive storm surge will occur near and just south of where the eye moves ashore, AccuWeather said. In fact, the hurricane is increasing in size as it approaches Florida, despite the fluctuations in wind speed.

'Unlike any in living memory'

"Milton's wind field is expected to continue to expand as it approaches Florida," the hurricane center said. "In fact, the official forecast shows the (field of) hurricane- and tropical-storm-force winds roughly doubling in size by the time it makes landfall. Therefore, damaging winds, life-threatening storm surge, and heavy rainfall will extend well outside the forecast cone."

According to the hurricane center, Milton’s tropical-storm-force winds extended roughly 125 miles from the center as of Wednesday morning and could be as far as 200 miles from the center by the time Milton makes landfall.

Milton will be a surge event unlike any hurricane in living memory for west-central Florida, with only major hurricane strikes in 1848 and 1921 comparable in scope and height of the coastal flooding, WeatherTiger meteorologist Ryan Truchelut said on his blog Tuesday afternoon.

"The powerful wind field in Milton’s eastern half will push a wall of water north onto the Gulf’s shallow continental shelf," he warned, "and any last-minute reduction in maximum winds will not reduce the volume of that onslaught."

What is the Saffir-Simpson Hurricane Wind Scale?

The Saffir-Simpson scale matches wind speeds with examples of the type of damage and impacts those winds could cause in the USA. In general, damage rises by about a factor of four for every category increase.

Watch the video below for a visual breakdown of the Saffir-Simpson scale of hurricane intensity for each category.

The scale was developed by structural engineer Herbert Saffir in 1969 as part of a United Nations project. It was later adapted by meteorologist Robert Simpson in the early 1970s, and it has been an integral tool for alerting the public about the possible impacts of various intensity hurricanes ever since, the National Hurricane Center said.

How much damage could Milton do in Florida?

Milton's true toll will depend on where it makes landfall, and how its other effects like flooding, storm surge and tornadoes unfold. But its wind speed and category at landfall will be key indicators of the extent of power outages and structural damage to come.

Read more: Disaster scenario warns of what Hurricane Milton could do to Tampa Bay

A Wednesday morning forecast from the National Hurricane Center shows the hurricane approaching landfall Wednesday night as a Category 4 with winds near 130 mph.

If it does hit at Cat 4 power, the storm by definition would be be expected to leave a trail of "catastrophic" damage. The National Hurricane Center says Category 4 storms threaten well-built framed homes with "severe" damage, potentially losing both roof and walls. Most trees are snapped or uprooted and power poles are downed.

"Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months," the hurricane center says of Category 4 storms.

A Category 3 storm, while significantly weaker, is still a major hurricane. "Electricity and water will be unavailable for several days to weeks after the storm passes," the center says of Category 3 storms.

What is a major hurricane?

Though all hurricanes produce life-threatening winds, hurricanes rated Category 3 and higher are known as major hurricanes. Major hurricanes can cause devastating to catastrophic wind damage and loss of life. Hurricanes of all categories can produce deadly storm surge, rain-induced floods and tornadoes.

What are the 5 hurricane categories?

Category 1 hurricane: 74-95 mph Very dangerous winds will produce some damage: Well-constructed frame homes could have damage to roof, shingles, vinyl siding and gutters. Large branches of trees will snap, and shallowly rooted trees may be toppled. Extensive damage to power lines and poles probably will result in power outages that could last a few to several days.

Category 2 hurricane: 96-110 mph Extremely dangerous winds will cause extensive damage: Well-constructed frame homes could sustain major roof and siding damage. Many shallowly rooted trees will be snapped or uprooted and block numerous roads. Near-total power loss is likely, including outages that could last from several days to weeks.

Category 3 hurricane (major): 111-129 mph Devastating damage will occur: Well-built framed homes may incur major damage or removal of roof decking and gable ends. Many trees will be snapped or uprooted, blocking numerous roads. Electricity and water will be unavailable for several days to weeks after the storm passes.

Category 4 hurricane (major): 130-156 mph Catastrophic damage will occur: Well-built framed homes can sustain severe damage with loss of most of the roof structure and/or some exterior walls. Most trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months.

Category 5 hurricane (major): 157 mph or higher Catastrophic damage will occur: A high percentage of framed homes will be destroyed; there will be total roof failure and wall collapse. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months. Most of the area will be uninhabitable for weeks or months.

(This story has been updated to add new information.)

This article originally appeared on USA TODAY: Hurricane Milton category isn't forecaster's biggest worry