Satellite Imagery Captures Stunning Cloud Formation Over Pacific Northwest
NASA's Terra satellite documents marine stratus clouds blanketing Washington and Oregon
1Marine cloud blanket formation
In mid-September 2026, cool marine air from the Pacific Ocean created an extensive layer of low-lying stratus clouds and fog across western Washington and Oregon. The cloud cover extended inland to the Cascade Range foothills, with coastal mountain ranges appearing as islands above the cloud layer. NASA's Terra satellite captured the phenomenon at 10:45 a.m. Pacific Time using its MODIS instrument, showing the cloud extent against smoke from North Cascades wildfires.
2Meteorological conditions
The National Weather Service reported consecutive nights of onshore marine air flow creating these cloud conditions. Marine stratus forms when moist surface air cools beneath a warmer inversion layer, causing water vapor condensation. The September 19 event was particularly strong, with fog occurring where clouds reached ground level. This atmospheric setup is characteristic of Pacific Northwest autumn weather patterns.
3Satellite observation timing
NASA's Terra satellite documented the extensive cloud cover at mid-morning, while the Aqua satellite's afternoon pass showed partial clearing. Some marine clouds persisted along the cooler Oregon coast. The 5.5-hour difference between observations demonstrates the diurnal variation in marine layer behavior, with solar heating typically dissipating inland clouds by afternoon.
4Scientific instrumentation
The Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra provided the cloud imagery with its 36 spectral bands. This instrument, operational since 1999, captures data at resolutions from 250m to 1km, ideal for tracking large-scale atmospheric phenomena. The image processing utilized NASA's EOSDIS LANCE and GIBS/Worldview systems for rapid data delivery.
5Regional climate context
The Pacific Northwest frequently experiences such marine layer events, particularly during seasonal transitions. A 2020 study in Geophysical Research Letters analyzed summertime low cloud patterns from 1996-2017 in this region. These clouds significantly impact local temperatures, often creating stark coastal-inland contrasts during morning hours before afternoon clearing.
6Operational meteorology
National Weather Service forecast discussions for Portland and Seattle detailed the marine layer dynamics during this period. Such forecasts are crucial for aviation, maritime operations, and wildfire management in the region. The simultaneous presence of wildfire smoke and marine clouds created complex visibility conditions across different terrain elevations.
7Atmospheric science significance
Marine stratus clouds play important roles in Earth's radiation balance by reflecting sunlight. NASA's Earth Observatory regularly documents such phenomena to study cloud-climate interactions. The December 2016 'Celebration of Clouds' collection highlighted similar events, demonstrating the value of long-term satellite records for atmospheric research.
8Public science communication
This imagery represents NASA Earth Observatory's mission to make complex atmospheric phenomena accessible. The accompanying article explains the science behind marine layer clouds while showcasing the region's dramatic topography. Such content bridges scientific observation with public understanding of weather patterns affecting daily life in the Pacific Northwest.
Original article: NASA — Satellite Imagery Captures Stunning Cloud Formation Over Pacific Northwest