Hurricane Simon Satellite Images Reveal a Category 4 Storm and Atmospheric Gravity Waves

Hurricane Simon, one of the slowest-developing tropical cyclones in the Eastern Pacific this season, passed near Mexico’s Pacific coast as a Category 4 storm on October 11, 2026. The hurricane’s sustained winds reached 250 kilometers per hour (155 miles per hour) as it moved north-northwest.

Satellite image shows Hurricane Simon off Mexico’s coast

Simon’s eye was approximately 50 kilometers (30 miles) offshore, between Manzanillo and Puerto Vallarta. The Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the Suomi National Polar-orbiting Partnership satellite captured this image on October 11 at approximately 2:30 p.m. local time (20:30 UT).

At the time, recorded sustained winds were about 210 kilometers per hour (130 miles per hour), according to the National Hurricane Center (NHC). The storm’s inner core was reaching the coast.

The Sierra Madre Mountains appeared to weaken some of the hurricane’s strength and reduce the size of its wind field, the NHC noted. Even so, Hurricane Simon brought heavy rain and flooding to coastal areas, including the port city of Manzanillo, while increasing the risk of landslides in mountainous regions, according to news coverage.

Hurricane Simon generated waves in the upper atmosphere

In the early morning hours of October 11, satellites also captured the effects of Hurricane Simon extending into the upper atmosphere. The nighttime image above, recorded by the VIIRS instrument aboard the NOAA-21 satellite, shows atmospheric gravity waves radiating from the hurricane.

These ripples form when latent heat released near a tropical cyclone’s eyewall drives strong convection and creates high cumulonimbus clouds. Powerful updrafts associated with those clouds can send waves into the stratosphere and mesosphere.

The waves are not always visible. Winds in the upper atmosphere can dissipate them before they reach the mesosphere, where they appear as ripples in airglow—a faint light emitted by high-altitude gases.

The VIIRS day-night band is sensitive to airglow, but it can also detect reflected moonlight, which may wash out the phenomenon. On the night this image was taken, limited moonlight helped accentuate the airglow.

Forecast uncertainty remained high on October 13

By the early morning of October 13, predictions for Hurricane Simon’s strength and path remained at “very low confidence” as the storm continued to evolve, according to meteorologists’ forecasts.

Depending on how the system developed, forecasts indicated that Simon could steer north and enter the Gulf of California before making landfall, according to the NHC key messages. Large swells were expected to create hazardous coastal conditions along parts of Mexico’s southwestern and west-central coasts in the following days.

NASA Earth Observatory image by Michala Garrison using NASA VIIRS data from the Land, Atmosphere Near real-time Capability for EOS (LANCE) and GIBS/Worldview, Suomi National Polar-orbiting Partnership, and the Joint Polar Satellite System (JPSS). Story by Lindsay Dorman.

October 11, 2026: Suomi National Polar-orbiting Partnership

October 11, 2026: NOAA-21

Sources

• Hoffman, L. et al. (2018). Satellite observation of stratospheric gravity waves accompanying the development of a tropical cyclone. Geophysical Research Letters, 45, 1692–1700.
• NASA (October 22, 2018). Why Does NASA Observe Airglow, the Color of the Wind in the Upper Atmosphere? Accessed October 13, 2026.
• NASA Earth Observatory (June 1, 2026). Gravitational Waves from Super Typhoon Shinraku. Accessed October 13, 2026.
• National Hurricane Center (October 13, 2026). Hurricane Simon Advisory Archive. Accessed October 13, 2026.
• Reuters (October 12, 2026). Hurricane Simon Crawls Along Mexico’s Pacific Coast, Causing Flooding and Evacuations. Accessed October 13, 2026.