J2.6
Extreme rainfall, hurricanes, and the Madden-Julian Oscillation: Impacts and predictability
Mathew Barlow, Univ. of Massachusetts, Lowell, MA; and J. Rhoads
Aspects of the Madden-Julian Oscillation (MJO) are predictable out to two weeks and beyond. This predictability, in combination with the well-known influence of the MJO on hurricane activity in the eastern Pacific and Gulf of Mexico raises the possibility of extended range forecasting of hurricane-related extreme events over North and Central America. We assess this predictability by: 1) examining the influence of hurricanes and tropical storms on North American extreme rain events, using daily station data; 2) determining the MJO influence on the hurricane-related extremes; 3) assessing the related predictability; and 4) quantifying the societal impacts for Mexico and Central America in terms of the occurrence of recorded flood and windstorm disasters.
The GHCN daily station data is used for precipitation, the HURRDAT database is used for hurricane and tropical storm locations, the CRED database is used for disaster records, and the Maharaj and Wheeler real-time forecast is used for the MJO. The period of analysis is 1974-2004. The influence of hurricanes and tropical storms on North American extreme precipitation events is extensive, even away from the most-affected coastal regions. For example, several stations in central Massachusetts have more than one-third of their 10 wettest days associated with hurricane or tropical storm activity. The hurricane influence on extreme events is clearly modulated by the MJO in several areas of Mexico and Central America, with an apparently weaker signal over the US – although this is still under investigation. In the most-affected areas, there appears to be predictability out to at least 10 days, even using an operational forecast of the MJO. Analysis of the disaster records shows a dominant influence of the MJO, with flood and windstorm disasters nearly *twice* as likely during the positive phase of the MJO as compared to the negative phase. Predictability of the disasters also appears to extend to at least 10 days.
Recorded presentationJoint Session 2, Operational Perspectives on the Societal--Prediction Link
Wednesday, 23 January 2008, 10:30 AM-12:00 PM, 214
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