The results of processing preexisting ionospheric storm data are presented to demonstrate the use of the long-term ionospheric anomaly monitoring (LTIAM) tool for developing a ground-based augmentation system (GBAS) ionospheric anomaly threat model. The LTIAM not only detect the worst ionospheric gradients successfully, but also populate the current GBAS threat space with newly discovered ionospheric anomalies. As an application of LTIAM, the paper also proposes a method of utilizing its outputs to understand the distribution of anomalous spatial gradients. Examining the gradients above 50 mm/km on known storm days demonstrates that smaller (but still anomalous) gradients are far more likely than extreme gradients above 200 mm/km. The continued use of LTIAM over the current and upcoming solar peaks is discussed to estimate the likelihood of large spatial gradients.