Rapid Intensification

Our technologies have come a long way!

1944 Navy hurricane reconnaissance team flying WWII Bombers B-25 to gather hurricane data

This is a repost of mine from October 2024. Hurricane Erin is a beast of a storm churning in the Atlantic. The current forecast indicates it will stay well offshore the CONUS, thankfully. But Erin had a fantastic display of rapid intensification that has the media in a frenzy.

In science circles, the study of rapid intensification has been a matter of some debate in the context of the recent DOE climate report. The DOE report did not discuss rapid intensification. The IPCC WG1 report states:

The global frequency of TC rapid intensification events has likely increased over the past four decades.

From my read of the discussion among scientists, the IPCC report, and the DOE report, my opinion is that technological advancement in recent decades-particularly as it pertains to the capabilities of the Hurricane Hunters, makes it difficult to say definitive things about trends in rapid intensification. This is especially so because these things happen out at sea.

One cannot discredit the first half of the hurricane record for data quality issues and then proclaim definitive things about the latter half of the record because of its high data quality.

Thus, where the DOE reports states:

While it has long been hypothesized that a rising global sea surface temperature would cause an increase in hurricane intensity, identification of any significant trend in the hurricane data is hampered by a short data record and substantial natural variability.

One could also add tremendous advancement in technological capabilities also add to challenges in making sense of recent trend data- particularly where observations are over the ocean.

Food for thought papers:

• Hagen et al (2012): A Reanalysis of the 1944–53 Atlantic Hurricane Seasons—The First Decade of Aircraft Reconnaissance

• Hagen and Landsea (2012): On the Classification of Extreme Atlantic Hurricanes Utilizing Mid-Twentieth-Century Monitoring Capabilities

My writing from last year…

As I write, Florida is bracing for the impacts of Hurricane Milton, a fierce storm that will be costly and memorable. My thoughts are with the people of this colorful state.

Prelude to Milton’s landfall is the media storm whirled up by the appropriate effort to notify the public of the coming threat, and newscasters working their superbowl moment.

Captivating the public is Hurricane Milton’s rapid intensification. Here is Climate.gov recounting early bouts of Milton’s rapid intensification:

Milton formed as a tropical depression over the southwestern Gulf of Mexico on Saturday, October 5, 2024. Just a couple hours after its formation the National Hurricane Center (NHC) deemed it a tropical storm. By Sunday afternoon, just 24-hours after becoming a named storm, Milton had rapidly intensified into a Category 1 hurricane. Rapid intensification is defined as a 35 mph increase in wind speed in 24 hours. 

From 1:00 p.m. CDT on Sunday to 1:00 p.m. CDT on Monday (a 24-hour period), Milton increased an additional 95 mph, more than doubling the requirement for rapid intensification. Based on these early numbers, this explosive amount of rapid intensification is only eclipsed by Wilma 2005 and Felix 2007 according to NHC records. Maximum sustained winds peaked at 180 mph on Monday afternoon (a strong Category 5) and the hurricane’s pressure bottomed out at 897 mb.

The media was awash with loud claims linking rapid intensification to fossil fuel emissions and anthropogenic climate change.

NBC’s National Climate Reporter

On this matter, the IPCC is more reserved than NBC attention grabbing reporters:

The global frequency of TC rapid intensification events has likely increased over the past four decades.

The statement deserves some context, and a proper tribute to the nation’s hurricane hunters and forecasters.

NOAA’s Hurricane Hunter’s capturing data to support forecasting

A characteristic of the chatter about Milton’s forecasting efforts is its emphasis on the work of the Hurricane Hunters. These are brave teams under NOAA and Air Force Reserve that fly into hurricanes to collect data in support of NHC forecasting efforts.

The practice is referred to as hurricane reconnaissance and it began in 1944. The photo at the top of the page is the first team (then, with the Army Air Force) to have made this effort. The reconnaissance team made their trip in a B-25, a popular WWII bomber.

Hurricane reconnaissance was a game changer for forecasting and observation capabilities prior to the development of satellites in the 1960s. By comparison, meteorologists recounting the experience forecasting the 1926 Great Miami Hurricane note that a challenge in getting a hurricane warning out to Miami was in part due to a lack of data about the storm as it moved west past the Bahamas into open water:

The notable feature of this table [ie observation data] is the small number of reports from oceanic areas and this is strikingly manifest for the 17th-the critical date. It may be that the advance notice of the presence of the storm deterred vessel masters from entering the storm area; any event the absence of reports from oceanic areas a critical times must be a serious handicap to any organization that attempts to forecast the coming of these destructive storms.

So, the development of aircraft reconnaissance was a big deal for hurricane forecasting.

Even still what hurricane hunters offer today is heaps more than they could in earlier days when they were limited not just by meteorological technology but by aircraft capability.

A 2012 paper by Andrew Hagan and Chris Landsea, cautions against about making adamant statements about trends regarding strong hurricanes in recent decades. They find that historic methods would not have captured characteristics of the strongest hurricanes with which we have recent experience:

The results suggest that intensity estimates for extreme tropical cyclones prior to the satellite era are unreliable for trend and variability analysis

There are specific mentions of the inability to capture rapid intensification of storms. This excerpt notes that in the 1940s, meteorologists would not have captured rapid intensification of Hurricane Katrina (2005):

The rapid intensification and subsequent rapid weakening that occurred in the Gulf of Mexico would not have been captured with the observational platforms of the late 1940s/early 1950s, and Katrina very likely would not have been listed as a Category 5. It would have been assumed that Katrina slowly intensified until reaching its peak intensity at landfall in Louisiana.

Should rapid intensification occur at night reconnaissance efforts defiantly would not have captured it because they did not fly at night nor did they fly into storms this strong. Here for Hurricane Wilma (2005):

The next aircraft flight occurred at night, and no intensity information was available during the late 1940s/early 1950s at night. That is the night when Wilma underwent its extreme rapid intensification. The first fix during daylight occurred at 1806 UTC 19 October. Aircraft in the late 1940s and early 1950s would not have been able to penetrate the center since the central pressure was below 940 mb.

What Hurricane Hunters are able to do today is a technological feat in comparison to what they could do in the 1940s. Hagan and coauthors (2012) give a careful account of the first decade of aircraft reconnaissance noting basic limitations:

Aircraft central pressures were only reported during daylight hours due to the need to visually see the ocean surface and primarily in tropical storms and minor hurricanes. Beginning in 1950 penetrations were generally attempted more often and for somewhat stronger hurricanes compared with the late 1940s (roughly a Saffir– Simpson category stronger on average). Nevertheless, it was still a common occurrence in the 1950s for a plane to attempt a penetration and have to abort before the RMW or even the inner core was reached due to extreme turbulence causing the plane to become uncontrollable

In my own scan of the literature the earliest mention of rapid intensification occurs in discussion of 1964 Hurricane Cleo written in the Monthly Weather Review.

MWR in 1966

The analysis presents brief discussion of these two images.

Which -goodness me- is a far cry from the analytical data and imagery we have today. Check out Ryan Maue at

Weather Trader

for his collection of data, imagery, and analyses.

Of course, as data collection capabilities increased so too did publications on ‘rapid intensification.’ Below is the annual count of papers in Web of Science mentioning rapid intensification and hurricane or tropical cyclone.

Web of Science

Today, NOAA boasts the ability of their Hurricane Hunters to use their aircraft to get “an MRI-like look at the storm” with planes that were acquired in the 1970s (though receiving substantial updates since).

Just last month NOAA announced an order in for new planes. Imagine the capabilities then!

Left: the original reconnaissance plane Right: the plane used today

So, when viewing claims about rapid intensification and climate change keep the above context in mind- which, is not to say that anthropogenic climate change is not relevant for the study of rapid intensification.

It is more the point that our fascination with rapid intensification is guided by our more recent ability to closely observe it.

Good luck to Florida and a big Thank You to our Hurricane Hunters.

Nine weather reconnaissance missions. Nine, y’all. Nine.