High Resolution Modelling for the Vancouver 2010 Olympics1Numerical Weather Prediction Research Section

Ron McTaggart-Cowan1

Manfred Dorninger3

Amin Erfani2

Andre Giguere2

Jocelyn Mailhot1

Jason Milbrandt1

Reinhold Steinacker3

5 November 2008

www.ec.gc.ca

2Canadian Meteorological Centre3University of Vienna

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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

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Vancouver 2010 Olympics

• Olympic games: 12-28 February 2010• Paralympic games: 12-21 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

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Vancouver 2010 Olympics

Vancouver

Whistler

CypressYVR

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: http://weatheroffice.pyr.ec.gc.ca/2010)

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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)

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Forecasting Challenges

• The Olympic venues cover highly varied terrain:

– Vancouver area - Fraser river delta

– Cypress - North Shore mountains 1000+ m above the Fraser Delta

– Whistler - Whistler Valley extends from Howe Sound

Domain for 1 km GEM model

Strait o

f Geo

rgia

Vancouver

Strait of Juan de Fuca

VancouverIsland

Pu

ge

t So

un

d

OlympicMountains

Whistler

Fra

ser

Val

ley

Pem

berto

n V

alley

Pitt L

ak

eHowe S.

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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

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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

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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)

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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

ChillHigh TempLow

TempRainVisibility WindNew

SnowSport and Weather

< - 20CX-Country

>3 but < 4 m/s or variability >45 but <90 degrees or gusts >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)

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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

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Production of High Resolution Guidance

GEM LAM

GEM LAM

GEM LAM

GEM LAM

GEM LAM

GEM LAM

06Z 18Z12Z 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

R1 R2 R1R1 R2

00Z

• Triple-nested integrations run twice daily from 0600 UTC and 1800 UTC GEM Regional forecasts

15 km

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2.5 km

Production of High Resolution Guidance• Triple-nested integrations run twice daily

from 0600 UTC and 1800 UTC GEM Regional forecasts

GEM LAM

GEM LAM

GEM LAM

GEM LAM

GEM LAM

GEM LAM

06Z 18Z12Z 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

R1 R2 R1R1 R2

00Z

15 km

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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

GEM LAM

GEM LAM

GEM LAM

GEM LAM

GEM LAM

06Z 18Z12Z 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

R1 R2 R1R1 R2

00Z 2.5 km

Vancouver

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• 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

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Example: Prognostic Snow-to-Liquid Ratio

Category

Density

Ice SnowGraupel

Description Pristine crystals Large crystalsor aggregates

Rimed crystals

Constant Diameter-basedConstant

Snow Diameter (mm)

Den

sity

(g/

cm3 )

(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 ForecastV1800 UTC3 Dec 2007

Snow-to-Liquid Ratio

2.5:1

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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 PrecipitationFingerprint

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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

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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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www.ec.gc.ca