High Resolution Modelling for the Vancouver 2010 Olympics 1 Numerical Weather Prediction Research Section Ron McTaggart-Cowan 1 Manfred Dorninger 3 Amin Erfani 2 Andre Giguere 2 Jocelyn Mailhot 1 Jason Milbrandt 1 Reinhold Steinacker 3 5 November Canadian Meteorological Centre 3 University of Vienna

10/31/08Page 2 Outline Vancouver 2010 description Forecasting challenges High resolution guidance in steep terrain –Description of the 1.0 km high resolution modelling system Analysis and model evaluation Discussion

10/31/08Page 3 Vancouver 2010 Olympics Olympic games: February 2010 Paralympic games: March 2010 Host cities: Vancouver, Whistler, Richmond, Surrey BC Organized by VANOC (local organizing committee) Weather observation and forecasting support provided by Environment Canada (EC) SNOW-2010 Nowcasting RDP led by EC

10/31/08Page 4 Vancouver 2010 Olympics Vancouver Whistler Cypress YVR YYJ The Olympic Autostation Network consists of almost 40 standard and special surface observing sites, all hourly or synop data available on the GTS. Additional data:  12-hourly soundings and profiler data from Squamish (WSK)  Additional doppler radar from Callaghan Valley ... Despite the (relatively) large number of surface stations, they are concentrated in a very small region (Source:

10/31/08Page 5 Vancouver 2010 Olympics Downhill skiing, sliding (i.e. bobsleigh, luge etc), cross-country skiing and biathlon will be held in the Whistler area. The autostation network has been designed to provide continuous sampling of “profiles” along the slopes of Whistler (western) and Blackcomb (eastern) mountains. Forecasters will be assigned to individual venues (downhill, Callaghan, sliding) for the games (Courtesy of G. Isaac)

10/31/08Page 6 Forecasting Challenges The Olympic venues cover highly varied terrain: –Vancouver area - Fraser river delta –Cypress - North Shore mountains m above the Fraser Delta –Whistler - Whistler Valley extends from Howe Sound Domain for 1 km GEM model Strait of Georgia Vancouver Strait of Juan de Fuca Vancouver Island Puget Sound Olympic Mountains Whistler Fraser Valley Pemberton Valley Pitt Lake Howe S.

10/31/08Page 7 Forecasting Challenges Local terrain-induced flows include: –Split flow around Olympics –Puget sound convergence zone (PSCZ) –Shallow, cold valley dynamically-driven outflow –Possible North Shore upsloping L Domain for 1 km GEM model

10/31/08Page 8 Forecasting Challenges Local terrain-induced flows include: –Reversal of valley flow to inflow, possibly overriding remnant cold dome –Moist onshore post- frontal flow –Case-dependent flow in marine channels L Domain for 1 km GEM model

10/31/08Page 9 Forecasting Challenges Forecasts are required twice daily, and cover ranges from nowcasting to day-2 at one-hour intervals Sample forecast form for the Slalom venue, proposed as part of the SNOW-V10 project. (Courtesy of G. Isaac)

10/31/08Page 10 Forecasting Challenges Forecasts are required twice daily, and cover ranges from nowcasting to day-2 at one-hour intervals Some of the Olympic events have extremely sensitive thresholds for caution/cancellation: Wind Chill High TempLow Temp RainVisibilityWindNew Snow Sport and Weather < - 20C X-Country >3 but 45 but 4m/s > 0C or sharply rising temperature tendency thru 0C. < - 20C Yes or no and how much > 4 m/s sustained or variability > 90 degrees Yes or no and how much Ski Jump (Courtesy of C. Doyle)

10/31/08Page 11 Production of High Resolution Guidance The goal of high resolution guidance is to add information about highly localized events –Wind channeling / gusts during frontal passage –Precipitation (type and quantity) –Visibility in valley cloud that forms fog at mid-mountain This information can be used to add value to lower-resolution model guidance (including ensemble) and standard mountain forecasting techniques

10/31/08Page 12 Production of High Resolution Guidance GEM LAM 06Z 18Z 12Z 00Z 15 km – 20 h 2.5 km – 17 h 1.0 km – 15 h 3h 2h Daily Nesting Strategy 15 km 1.0 km 2.5 km R1R2R1 R2 00Z Triple-nested integrations run twice daily from 0600 UTC and 1800 UTC GEM Regional forecasts 15 km

10/31/08Page km Production of High Resolution Guidance Triple-nested integrations run twice daily from 0600 UTC and 1800 UTC GEM Regional forecasts GEM LAM 06Z 18Z 12Z 00Z 15 km – 20 h 2.5 km – 17 h 1.0 km – 15 h 3h 2h Daily Nesting Strategy 15 km 1.0 km 2.5 km R1R2R1 R2 00Z 15 km

10/31/08Page 14 1 km Whistler Production of High Resolution Guidance Triple-nested integrations run twice daily from 0600 UTC and 1800 UTC GEM Regional forecasts GEM LAM 06Z 18Z 12Z 00Z 15 km – 20 h 2.5 km – 17 h 1.0 km – 15 h 3h 2h Daily Nesting Strategy 15 km 1.0 km 2.5 km R1R2R1 R2 00Z 2.5 km Vancouver

10/31/08Page 15 Refinements to the GEM model for use at high resolution in steep terrain are under evaluation. For example: –Inclusion of land slope and aspect for computing the radiative balance of the surface –Double moment bulk microphysics with a prognostic snow/liquid ratio (snow density) –Wind variance and gust diagnostics –Visibility reduction due to hydrometeors Production of High Resolution Guidance

10/31/08Page 16 Example: Prognostic Snow-to-Liquid Ratio Category Density IceSnowGraupel Description Pristine crystals Large crystals or aggregates Rimed crystals ConstantDiameter-basedConstant Snow Diameter (mm) Density (g/cm 3 ) (Source: Thompson et al. 2008) Volume(Ice) + Volume(Graupel) + Volume(Snow) = Predicted Snowfall Rate (cm/h) and Snow:Liquid Ratio Predicted snow-to-liquid ratio values vary from 2.5:1 (primarily graupel, small crystals and mixed precip) to well over 20:1 (large aggregates and dendrites). 75:1 20:1 10:1 40:1 06h Forecast V1800 UTC 3 Dec 2007 Snow-to-Liquid Ratio 2.5:1

10/31/08Page 17 High Resolution Analysis Observing networks are inhomogeneous in mountains Traditional analysis schemes: –Rely heavily on model-generated first guess fields –Reduce data and smooth analysis in mountains The Vienna Enhanced Resolution Analysis (VERA) uses physically-derived “fingerprints” to locally extend the impact of surface observations, eliminating the need for a background (Steinacker et al. 2006) (Bica and Steinacker 2006) Idealized Ororgraphy Upslope Precipitation Fingerprint

10/31/08Page 18 High Resolution Analysis The VERA analysis uses no model background: model- independent Analysis resolution varies with observation spacing, but will be 4 km in southwestern British Columbia VERA surface analyses can be used for both nowcasting and real-time high resolution model evaluation VERA Analysis of MSLP and potential temperature (16 km prototype) for the Olympics region

10/31/08Page 19 Discussion Vancouver/Whistler will host the Winter Olympics in Feb- March 2010 An Olympic autostation network and remote sensing data support SNOW-V10 RDP A 3-nest high resolution (1 km) forecast system has been designed to provide hourly guidance to forecasters (slope, microphysics, wind, visibility…) Evaluation (VERA and subjective) of the forecast system will continue during the January-March test period in 2009

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