A localized, persistent, often abrupt lowering from a rain-free base. Wall clouds can range from a fraction of a mile up to nearly five miles in diameter, and normally are found on the south or southwest (inflow) side of the thunderstorm in the Northern Hemisphere. When seen from within several miles, many wall clouds exhibit [...]
According to the National Weather Service, a warning is issued when a hazardous weather or hydrologic event is occurring, is imminent, or has a very high probability of occurring. A warning is used for conditions posing a threat to life or property.
According to the National Weather Service, a watch is used when the risk of a hazardous weather or hydrologic event has increased significantly, but its occurrence, location, and/or timing is still uncertain. A watch is intended to provide enough lead time so that those who need to set their plans in motion can do so.