Why did Moses leave the city to pray only during the plague of hail and not during the other plagues?

This source-based Torah study examines the question: Why did Moses leave the city to pray only during the plague of hail and not during the other plagues? The canonical Hebrew discussion develops the issue through the weekly Torah portion and the sources cited there, preserving the distinctions, tensions, and practical implications of the original text. This localized discovery layer does not add any new halakhic, medical, legal, scientific, historical, theological, or empirical ruling or claim beyond the canonical Hebrew source.