1.4 The July Floods in Pakistan: Could They Have Been Predicted?

Tuesday, 25 January 2011: 9:30 AM
6B (Washington State Convention Center)
Peter. J. Webster, Georgia Institute of Technology, Atlanta, GA; and R. A. Houze Jr.

During July 2010, deluges in northern Pakistan resulted in catastrophic flooding, loss of life and property and agricultural impacts that will extend for years. Whereas the overall rainfall was not extraordinary for Pakistan in the summer monsoon season, the rate of precipitation was exceptional, and data from the TRMM satellite show that it was associated with convective phenomena more usually associated with eastern India and Bangladesh. Furthermore, the location of the precipitation, occurring in a series of waves throughout, occurred in arid regions lacking vegetation to slow down the accumulation of water in the valleys. Thus the rate of rainfall and its location conspired to produce an exceptional circumstance. We present a detailed morphology of the rainfall events leading up to the flooding. But could the floods have been predicted? Using the ECMWF EPS system, we show that each wave of precipitation over northern Pakistan was predictable 6-8 days in advance with a very high probability of extreme rainfall. We conclude that the use of probabilistic forecasts and the incorporation of a hydrological model such as we have developed for Bangladesh. Moreover, together with knowledge of storm structures recently derived TRMM, these forecasts could have provided a timely warning allowing the evacuation and the saving of lives and property.
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