In order to provide a more reliable situational awareness of scintillation impacts on users of space-based communication/navigation systems, L-band scintillation measurements from GPS satellites are ingested, in real time, to the Scintillation Network Decision Aid (SCINDA) model. SCINDA is a real-time, data-driven communication outage forecast and alert system developed by the Air Force Research Laboratory at Hanscom Air Force Base and made operational through a joint effort between the U.S. Air Force and the U.S. Navy. UHF and L-band scintillation parameters are measured, modeled, and propagated in time to provide a regional specification of the scintillation environment in an effort to mitigate the impacts on the satellite communications (SATCOM) community. In an effort to provide UHF SATCOM users with a more consistent estimation of scintillation impacts on their systems, GPS sensors, measuring S4 at L-band frequency, are now used as a supplement to the stationary UHF links dramatically increasing the regional coverage at each individual station, particularly those located outside the anomaly crest. Three-dimensional representations of GPS observed plumes are mapped to the ground from the location of a selected satellite, producing a scintillation specification map detailing outage regions on the globe. In this paper we present results from a validation study of the GPS proxy model and demonstrate its usefulness as an adjunct to the SCINDA model in producing the most accurate and reliable nowcast and forecast scintillation specification products available to UHF SATCOM users.