5.36 WSN05 Toulouse France, 5-9 September 2005 New Approaches for Nowcasting Winter Road Weather Over a Complex Orography Willi Schmid, meteoradar gmbh Albert Mathis, AnyData ag Urs Keller, MeteoSwiss 5.36 WSN05 Toulouse France, 5-9 September 2005 Winter weather at WSN05 (without fog) Winter road weather1(the present) Winter airport/aircraft weather6 5.36 WSN05 Toulouse France, 5-9 September 2005 Decision making Snow removal / salting Modern Traditional RWIS-stations Weather-forecasts RWIS-stations Weather-forecasts Road-forecast 5.36 WSN05 Toulouse France, 5-9 September 2005 Road forecast 0-2 hours Road-forecast RWIS-station Advection Precipitation Temperature 5.36 WSN05 Toulouse France, 5-9 September 2005 Our Goal To develop fully automated procedures, providing a)Good probability forecasts for critical road parameters b)Good threshold values for correct decisions 5.36 WSN05 Toulouse France, 5-9 September 2005 Issues of this presentation Detection of winter precipitation with radar Precipitation type (rain/snow/black ice) from radar/ground data Radar image extrapolation Cloudiness from temperature measurements Surface temperature forecasts from extrapolated cloudiness Risk forecasts snowfall/black ice/freezing rainwater Road state forecasts from radar and ground data Intervention management 5.36 WSN05 Toulouse France, 5-9 September 2005 Radar-detected precipitation is confirmed on the ground in 65% of all cases. Precipitation on the ground is seen with radar in 35% of all cases Explanation ? Radar and reality Comparison radar optical sensor on ground 5.36 WSN05 Toulouse France, 5-9 September 2005 Fraction of snow in precipitation KSSG method (Koistinen/Saltikoff/Schmid/Gjertsen) * * * * * o o o o o o o ** 0 1 P =P = T T T T T 5.36 WSN05 Toulouse France, 5-9 September 2005 Melting layer 5.36 WSN05 Toulouse France, 5-9 September 2005 Validation KSSG method Jan / Feb 2004 KSSG method Radar / Anetz 72 stations Switzerland Temperature/Humidity 10 min Optical sensor PWD11 (Vaisala) 52 stations Canton of Lucerne Rain / snow direct 15 min 5.36 WSN05 Toulouse France, 5-9 September 2005 KSSG and reality Rain predicted Snow predicted Total Rain observed % % 4101 Snow observed % % 6998 Total % 92.4 % are correct 5.36 WSN05 Toulouse France, 5-9 September 2005 Radar image extrapolation 5.36 WSN05 Toulouse France, 5-9 September 2005 COTREC / Raincast / Raincast+ COTREC radar image extrapolation, ETH Jrg Joss, Li Li, Susanne Mecklenburg Raincast risk forecast rain/hail, ETH, 1999 2001 Raincast+ risk forecast snowfall/black ice, 5.36 WSN05 Toulouse France, 5-9 September 2005 Risk forecast precipitation. 100% 0% Risk 5.36 WSN05 Toulouse France, 5-9 September 2005 Risk forecast snowfall/snow cover 5.36 WSN05 Toulouse France, 5-9 September 2005 Cloudiness Thesis Tobias Grimbacher, IACETH, 2004 Temperature 2m above ground Surface temperature 5.36 WSN05 Toulouse France, 5-9 September 2005 Cloudiness Precipitation Clear Overcast Cloudy 5.36 WSN05 Toulouse France, 5-9 September Reliable method Cheap measurements Errors treatable Extrapolation possible Forecasts 1 hour - Dense network required Need more validation Ground temperature extrapolation Based on extrapolated cloudiness Grimbacher et al. To appear in Meteorol. Appl. 5.36 WSN05 Toulouse France, 5-9 September 2005 Projects 1999 COTREC / RainCastradar image extrapolation Precipitation typerain / snowfall / freezing rain Cloud coverfreezing rainwater Intervention managementIMWS 5.36 WSN05 Toulouse France, 5-9 September 2005 The IMWS project ( ) IMWS = Intervention management winter service Canton of Lucerne, Albert Mathis 13 decision criteria Precipitation Clouds Fog Decision go/nogo Hit rate: better than 95 % ! 5.36 WSN05 Toulouse France, 5-9 September 2005 Thank You 5.36 WSN05 Toulouse France, 5-9 September 2005