Some areas north of the DFW metroplex picked up close to 11 inches of rain since late last night due to a slow-moving disturbance tracking across north Texas. While this storm hasn’t been classified as one yet, now is a good time to explain what a 100-year storm is.
A 100-year storm refers to rainfall totals that have a one percent probability of occurring at that location in that year. In other words, there is a 1 in 100 or 1% chance that a storm will reach or exceed this intensity in any given year. Encountering a “100-year storm” on one day does not decrease the chance of a second 100-year storm occurring in that same year or any year to follow. Likewise, a 50-year storm has a 1 in 50 (or 2%) chance of occurring in a year.