After forming in the Bay of Campeche, Hurricane Milton underwent a remarkable period of rapid intensification with its central pressure falling from 1007 mb (29.74 inches of mercury, inHg) at 11:00 a.m. EDT Oct. 5 to 897 mb (26.49 inHg) at 8:00 p.m. EDT on Oct. 7. At this time Milton became the fifth most intense hurricane in the Atlantic Basin on record in terms of central pressure, behind Hurricane Rita (2005), and only the sixth storm in the Atlantic to have a central pressure below 900 mb.  In the process, Milton became the fastest Atlantic storm to intensify from a tropical depression to a Category 5 hurricane, with maximum sustained winds increasing from 35 mph to 160 mph in just over 48 hours. 

Like Helene, Milton’s formation appears to have been influenced by the Central American gyre, a seasonal area of low pressure centered over Central America that results in a large-scale counterclockwise or cyclonic flow that can extend over the western Caribbean, southern Gulf of Mexico including the Bay of Campeche, and far eastern Pacific.  At the start of October, there was broad but generally disorganized thunderstorm activity within this area stretching from the western Caribbean and into the southern Gulf of Mexico.  However, after a trough of low pressure rotated from the southeastern into the southwestern Gulf thunderstorm activity began to consolidate in the southwestern Gulf in the Bay of Campeche.  Persistent thunderstorm activity in this area then led to the formation of an area of low pressure, and by 10:00 a.m. CDT on Oct. 5, the National Hurricane Center (NHC) determined that thunderstorm activity associated with this low was sufficiently organized to be a tropical depression.  However, shortly thereafter at 12:25 p.m. CDT, NHC found winds of 40 mph, marking the formation of Tropical Storm Milton.  At this time Milton was centered about 225 miles north-northeast of Veracruz, Mexico and drifting very slowly north-northeast at 3 mph. 

Milton continued to slowly organize throughout the remainder of the day into the early morning hours of Oct. 6.  Milton then strengthened into a strong tropical storm, and following continued thunderstorm activity near the core, by 2:00 p.m. EDT had reached hurricane intensity with maximum sustained winds of 80 mph.  Milton continued to slowly strengthen with winds reaching 90 mph by 11:00 p.m. EDT when the center of the storm was located about 230 miles west-northwest of Progreso, Mexico, and moving east at 7 mph.  Several hours later the NASA/JAXA GPM Core Observatory flew over Milton.

Download this video in high resolution from the NASA Scientific Visualization Studio 

The above animation begins by showing surface rainfall estimates associated with Milton, derived from NASA’s IMERG precipitation product.  The animation begins at 1:41 a.m. CDT (06:41 UTC) Oct. 6, 2024, just over 13 hours after Milton became a tropical storm.  IMERG shows Milton transitioning from an asymmetric structure with a large north-south oriented rainband (shown as an orange and red arc) west of the center into a more compact system with most of the heavy rain (shown in red) concentrated nearer the center.

The second part of the animation shows a detailed look at the structure and intensity of precipitation within Milton from the GPM Core Observatory when it flew over the storm around 2:11 a.m. CDT  (7:11 UTC) on Oct. . At this time Milton was centered about 220 miles west-northwest of Progreso, Mexico.  Surface rainfall estimates from the GPM Microwave Imager (GMI) show heavy (red areas) to intense (magenta) rain wrapping into the storm northeast of the center, while GPM’s Dual-frequency Precipitation Radar (DPR) shows an area of intense rain immediately north of the center in the northern eyewall. 

The DPR can also provide a 3D perspective of the precipitation structure within the storm.  Areas shaded in blue denote frozen precipitation aloft.  The DPR shows that Milton has a very compact center, as evidenced by the relatively small ring of echo tops (blue annulus) surrounding the center.  The height of this precipitation is also a good indication of thunderstorm intensity, and the DPR shows several deep towers extending well above 10 km in the northern part of Milton’s eyewall associated with the area of intense surface rain.  Together this indicates intense thunderstorm activity in the northern eyewall.  This results in large amounts of heat being released into the core of the storm and is usually a good indicator of further strengthening. 

At the time of the GPM overpass, Milton was still a Category 1 hurricane with NHC reporting sustained winds of 90 mph.  However, it was soon after that Milton began to rapidly strengthen with maximum sustained winds reaching 100 mph by 4:00 a.m. CDT, 125 mph by 7:00 a.m. CDT, 155 mph by 10:00 a.m. CDT, and 175 mph by 1:00 p.m. CDT.

Credits:

Visualization by Alex Kekesi (NASA GSFC / GST) and the NASA Goddard Scientific Visualization Studio using GPM data.

Story by Steve Lang (NASA GSFC / SSAI) with edits by George Huffman (NASA GSFC) and Jacob Reed (NASA GSFC / Telophase)