to share – to copy, distribute and transmit the work
to remix – to adapt the work
Under the following conditions:
attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.
This image is in the public domain because it was stored on the web servers of the U.S. National Weather Service. NWS-created images are automatically public domain in the U.S. since the NWS is a part of the U.S. government. However, the NWS sites also host non-NWS images which have been submitted by individuals: these are generally shown as "Courtesy of ...". Such images have explicitly been released to the public domain by the copyright owner as part of the upload process.
As stated at https://www.weather.gov/fsd/disclaimer: "By submitting images, you understand that your image is being released into the public domain. This means that your photo or video may be downloaded, copied, and used by others."