There is a general online SKYWARN training class available. This course may or may not be accepted by local NWS forecast offices as a substitute for their local training so its advised to check in with your local weather office on whether this will serve as credit for classes held at the local level. Nonetheless, it is additional training that can be helpful for weather spotting and if you cannot attend a training session in your area or if they are not offered in your local area, it can give you an idea of what to look for from a weather spotting perspective.