Torrential rains in excess of 40 inches (1.016 meters) deluged Thailand’s Malay Peninsula this week, triggering floods that have killed at least 17 people. The floods submerged 61 major highways, affected 840,000 people, and forced the helicopter rescue of thousands of stranded tourists. Late March is usually a fairly dry time of year for Thailand, but near-record cold air settled in over the region this week, dropping temperatures to 5 – 10°C (9 – 18°F) below average. Heavy storms accompanied the cold air, and downpours with rainfall rates of up to 2 inches/hour affected the region for many days in a row. Sea surface temperatures of the waters surrounding the flood regions were near average, but were plenty warm enough to supply copious moisture to feed the storms. Flood recovery will slowed by additional moderately heavy rains of 3 – 5 inches expected to fall over the flooded region during the next week, according to the latest precipitation forecast from the GFS model.

Figure 1. The Multisatellite Precipitation Analysis (TMPA) analysis above was made using data that were calibrated using data from NASA’s TRMM satellite. This analysis shows that rainfall for the past week over the Malay Peninsula was particularly extreme with totals of almost 1200 mm (~47 inches). TRMM satellite data revealed that rainfall in that area was frequently falling at a rate of over 50 mm/hr (~2 inches/hr). Image credit: NASA.

Jeff Masters