TEAMG forecasts heavy rainfall of 100-150 mm/day on September 26-27 in Bangkok and surrounding areas, exceeding the drainage system's 60 mm/day capacity. The primary concern is localized water accumulation in canals and low-lying areas due to inadequate drainage rather than river flooding. Street water levels are expected to reach 10-20 cm in areas near canals and up to 50 cm in some depression zones. The Chao Phraya River remains at safe levels.