Liu, Yubao
Will Y.Y. Cheng, Yuewei Liu, LinlIn Pan, Gregory Roux, Wanli Wu, National
Center for Atmospheric Research/RAL;
Seung-Woo Lee, Young-Jean Choi, Young-San Park, Korea Meteorological
Administration, and Song-Lak Kang, Texas Tech University
Heavy rainfall around
the national capital Seoul and nearby Siheung regions in South Korea in late
July 2011 triggered flash floods and landslides that killed nearly 70 people by
July 28. At least 86 power outages followed the landslides, affecting 125,000
people by July 27. Over 11,000 South Koreans were forced to evacuate. The
NCAR-ATEC WRF-based Real-Time Four-Dimensional Data Assimilation and
forecasting system (RTFDDA) and its ensemble model E-RTFDDA were used to
conduct retrospective forecasting experiments aiming to test and demonstrate the
WRF-RTFDDA modeling capability of forecasting such high impact weather event.
The result of the modeling experiments shows that 1) the WRF-RTFDDA system
forecast over 650mm rainfall during July 26 and 27 in the Seoul regions, which
is very close to what was measured; 2) the spun-up cloud and precipitation, and
dynamical processes with the WRF-RTFDDA 4D continuous data assimilation scheme
significantly improve the prediction of the major precipitation episodes; 3)
the rapid-update FDDA and forecasting cycles are able to continuously update
the longer-range forecast with more accurate shorter-range forecasts; and 4)
properly setting the model domain locations can have a great impact on the
simulation of the convective systems. Analysis of the output of the E-RTFDDA
modeling forecasts for the event is under way and the result will also be
reported at the workshop.