As of Thursday morning, the 180-mph Hurricane Irma continues to pose a grave threat to the southeastern United States. The best available modeling continues to suggest this will probably be a historically bad storm for much of the southern half of Florida.

There remains a chance that Irma will turn north before reaching Florida and move to the east of the peninsula, which would leave the state on the drier side of the storm, with lesser winds and surge. But a 30 to 40 percent chance is not something we would gamble our lives and property on. If an evacuation order is called for your area, heed it.

You may have noticed some people are kind of freaking out about Irma, and we expect that to only get worse as the storm approaches Florida this weekend. And although it is certainly better to prepare for a hurricane rather than panic, there are some pretty legitimate reasons for extreme concern.

Warm water

Hurricanes feed off of warm water at the surface of the ocean—the greater the temperature difference between the surface and the mid-levels of the atmosphere, the more potential energy a storm has. As a general rule, sea surface temperatures of about 26.5° Celsius are warm enough to allow hurricanes to strengthen.

Unfortunately, over the next two or three days Irma will move over an area of ocean just north of the Caribbean Sea even warmer than the waters it is now crossing. In fact, the waters between Cuba and the Bahamas are warmer than 30° Celsius.

Low wind shear

Truthfully, hurricane scientists do not fully understand the processes by which hurricanes change their intensity. We understand, broadly, that storms require warm water to form and strengthen, and that factors such as high wind shear can break them apart.

Wind shear measures the difference of wind speed and directions at varying levels of the atmosphere. Typically, it is measured in knots, and for tropical cyclones a wind shear of 20 knots and above is unfavorable for development, with greater amounts tearing storms apart. Alas, the current wind shear environment along Irma's path is favorable for the storm's organization. Wind shear may increase as the the storm approaches the southern Florida coast, but by then it may be too late to matter a whole lot.

The official forecast weakens Irma some over the next three days (making landfall as a 150-mph hurricane), and this is because some of the intensity models show such weakening. Also, historically, forecasters just haven't seen a storm maintain such intense, 170- or 180-mph winds over multiple days at a time. Storms go through a process known as an eyewall replacement cycle which leads to some fluctuations in intensity.

Truth be told, however, it won't matter a whole lot whether Irma is 150-, 160-, or 170-mph if it makes landfall in southern Florida. It will cause widespread, significant damage with its large field of hurricane-force winds.

Early damages

The early returns of damages across Caribbean Islands in the northeastern Caribbean Sea are sobering. The small island of Barbuda, which took a direct hit, reported that nearly 100 percent of structures were severely damaged or completely destroyed. The island is said by some living there to "barely inhabitable."

GERBEN VAN ES/AFP/Getty Images

GERBEN VAN ES/AFP/Getty Images

Jose Jimenez/Getty Images

.Jose Jimenez/Getty Images

On Wednesday, the storm passed to the north of Puerto Rico, close enough to bring severe damage. Later on Thursday, it should move almost directly over the popular tourist destination Turks and Caicos, as well as some of the islands of the Bahamas. The early photos from these storms offer a sober reminder of the destructive potential of such a hurricane.

Meteorological records

Hurricane expert Phil Klotzbach is keeping a running tally of the meteorological records being set by Hurricane Irma as it moves across the Atlantic Ocean toward Florida. Through Wednesday night, according to Klotzbach, Irma has set the following marks:

185 mph lifetime max winds : Tied with Florida Keys (1935), Gilbert (1988) and Wilma (2005) for second strongest max winds of all time in Atlantic hurricane. Allen had max winds of 190 mph in 1980.

: Tied with Florida Keys (1935), Gilbert (1988) and Wilma (2005) for second strongest max winds of all time in Atlantic hurricane. Allen had max winds of 190 mph in 1980. 185 mph lifetime max winds : Strongest storm on record to impact the Leeward Islands, defined as 15-19°N, 65-60°W for this calculation. Okeechobee Hurricane (1928) and David (1979) were previous strongest at 160 mph.

: Strongest storm on record to impact the Leeward Islands, defined as 15-19°N, 65-60°W for this calculation. Okeechobee Hurricane (1928) and David (1979) were previous strongest at 160 mph. 185 mph lifetime max winds : Strongest storm to exist outside of the Caribbean and Gulf of Mexico on record.

: Strongest storm to exist outside of the Caribbean and Gulf of Mexico on record. 185 mph max winds for 33 hours : The longest any cyclone around the globe has maintained that intensity on record. The previous record was Haiyan in the NW Pacific at 24 hours.

: The longest any cyclone around the globe has maintained that intensity on record. The previous record was Haiyan in the NW Pacific at 24 hours. 914 mb lifetime minimum central pressure : Lowest since Dean (2007) and 10th lowest in satellite era (since 1966).

: Lowest since Dean (2007) and 10th lowest in satellite era (since 1966). 914 mb lifetime minimum central pressure : Lowest pressure by an Atlantic hurricane outside of the western Caribbean and Gulf of Mexico on record.

: Lowest pressure by an Atlantic hurricane outside of the western Caribbean and Gulf of Mexico on record. 1.75 days as a Category 5 hurricane: Tied with David (1979), Mitch (1998) and Isabel (2003) for 4th most Category 5 hurricane days on record.

Quiet period ends

In the coming days much will be said about Irma and climate change. Certainly, warmer seas make the high-end intensification of such systems more likely. However, it is not possible to determine precisely how much, nor is it accurate to say climate change "caused" Irma. Most likely, it caused Irma to be worse. Finally, it is worth noting that many of the aforementioned records were only recorded since the beginning of the satellite era, when scientists were able to track storms out at sea more continuously.

Despite some notable exceptions, such as Hurricane Sandy in 2012, the United States has had a relatively quiescent period in significant hurricane landfalls during the last decade. That has now ended. It seems plausible that the the country's two costliest storms on record—Harvey and Irma—could come within the same year. Please consider helping those in need over the coming weeks and months.