Hurricane Simon, the latest in along progressionof tropical cyclones in the Eastern Pacific this season, passed close to the Mexican coast as a category 4 storm on October 11, 2026.
Sustained winds reached 250 kilometers per hour as it crept north-northwest.
Simon’s eye was about 50 kilometers offshore, between Manzanillo and Puerto Vallarta, when theVIIRS on the Suomi NPPsatellite acquired this image around 2:30 p.m. local time on October 11.
By that time, sustained winds were about 210 kilometers per hour, according to the National Hurricane Center, and the storm’s inner core was brushing up against the coast.
The topography of the Sierra Madre mountains appeared to temper the storm’s intensity somewhat and shrink the size of its wind field, the NHC noted.
Still, the major hurricane delivered heavy rain and flooding to coastal areas, including the port city of Manzanillo, and raised the risk of mudslides in mountainous areas, according tonews reports.
In the early morning hours of October 11, satellites captured the storm’s effects extending into theupper atmosphere.
This nighttime image, acquired withVIIRSon theNOAA-21satellite, shows atmospheric gravity waves radiating from the hurricane.
These ripples form when latent heat released near the tropical cyclone’s eyewall drives strong convection, buildingtall cumulonimbus cloudswith updrafts that can send waves into the stratosphere and mesosphere.
But these waves are not always observable.
Winds in the upper atmosphere can dissipate them before they reach the mesosphere, where they show up as ripples in airglow—faint light emitted by gases at those high altitudes.
The VIIRSday-night bandis sensitive to airglow but also detects reflected moonlight, which can wash it out.
On the night this image was acquired, minimal illuminationfrom the Moon helped the airglow stand out.
On the morning of October 13, forecasts of Simon’s intensity and path remained “very low confidence,” as the storm’s evolution continued todefy meteorologists’ expectations.
The system maysteer northand enter the Gulf of California before making landfall.
Large swells causing dangerous nearshore conditions were expected along portions of the southwestern and west-central coasts of Mexico in the coming days.
NASA Earth Observatory images by Michala Garrison, using VIIRS data from NASAEOSDIS LANCE,GIBS/Worldview, the Suomi National Polar-orbiting Partnership, and the Joint Polar Satellite System.
Story by Lindsey Doermann.
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Hoffmann, L.,et al.Satellite observations of stratospheric gravity waves associated with the intensification of tropical cyclones. Geophysical Research Letters, 45, 1692–1700.
NASAWhy NASA Watches Airglow, the Colors of the Wind. Accessed October 13, 2026.
NASA Earth ObservatoryGravity Waves From Super Typhoon Sinlaku. Accessed October 13, 2026.
National Hurricane CenterHurricane SIMON Advisory Archive. Accessed October 13, 2026.
ReutersHurricane Simon crawls along Mexico’s Pacific coast, bringing floods and evacuations. Accessed October 13, 2026.
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