Lothar stormIntroductionThe Lothar storm that swept across Europe during 24-27 December 1999 is provided as a sample case study to use with OpenIFS. This storm was one of several severe storms to hit Europe in December 1999 and Lothar affected northern France, Switzerland and Germany (for more details see: Wernli et al., 2002, QJRMS; Ulbrich et al., 2001, Weather, 56, 70-80). The storms were characterized by record-breaking windspeed observations and rapid development across Europe. There was also a band of extremely high baroclinity near the cyclone track over the N. Atlantic and partly into Europe associated with Lothar. The ECMWF forecasting system of the time did not accurately capture the storm's intensity though the strong jet stream was predicted some 9 days earlier. The storm initiated from a small disturbance in the Atlantic. More recently, Wedi et al, 2012, ECMWF Newsletter, have shown that very high resolution (T7999; ~2.5km) is necessary to accurately model the high wind speeds observed, particularly over the mountainous regions of Europe. A number of initial conditions are provided along with suggested exercises. Feedback on this case study (and others) is welcomed. |