The Global Navigation Satellite System (GNSS) is widely used for real-time monitoring and early warning of geohazards. Accurate modeling of tropospheric delays is critical to achieving high-precision GNSS solutions, and using external delays can improve real-time GNSS convergence times. Current empirical delay models only provide delay but not uncertainty. We propose a global empirical delay model with uncertainty and demonstrate its benefits in accelerating GNSS positioning convergence.