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Communicating forecast uncertainty from theMet Office convective-scale ensemble for theLondon 2012 Olympic Games
Andrew Bennett, Caroline Jones, Stephen Moseley, Ken Mylne, Clive Pierce, Nigel Roberts, …Met Office, Fitzroy Road, Exeter EX1 3PB
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Outline
• Why?
• How?
• Products tour
• Feedback
• Summary
© Crown copyright Met Office
Aims
• Advertise the cutting-edge science being delivered by the Met Office
• Enhance forecasting guidance by providing a range of scenarios for decision-making
• Clear-language documentation of the products that everyone can understand
• Demonstrate the utility of probabilistic, high-resolution forecasting
© Crown copyright Met Office
Met Office ensemble systemsEarly 2012
Global (MOGREPS-G)•12 members, 6h update•Products use 24 lagged members•60km at mid-lats, 70 levels, to T+72h•IC and model parameters perturbations
Regional (MOGREPS-R)•12 members, 6h update•Products use 24 lagged members•18km at mid-lats, 70 levels, to T+60h•IC and model parameters perturbations
MOGREPS-15•Run at ECMWF•Global•24 members•To T+15 days•60km, 70 levels
MOGREPS-UK•12 members, 6h update•2.2km, 70 levels•IC perturbations and BC from MOGREPS-R (no high-res perturbations)•Initially to T+6h on IBM Power6•To T+36h on upgrade to Power7
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Mogreps-UK…
Undersampling leaves “holes” of zero-probability where showers could still occurHoles filled in
Creation of probability of rain product
…with Neighbourhood methodNigel Roberts
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The front page
Local time
Descriptors
Documentation for different audiences
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Rainfall products
Chance of rain over coming day Chance of rain within each hour
• Derived from 5min timestep rain rates• Thresholds: any (>0.2 mm/h), heavy (>4 mm/h), torrential (>16mm/h)
Chance of a mostly (very) wet hour
MOGREPS-UK 29th July 03:00 GMT run
e.g. chance of torrential (>16mm/h) rain over period 06:00 to 00:00 GMT
e.g. chance of torrential (>16mm/h) rain within each hour
e.g. chance of a mostly wet(>0.2 mm/h) hour
© Crown copyright Met Office
Temperature products• Chance of temperature exceeding 20, 25, 30, 32°C at
screen-level – useful for sea breezes• Daytime ensemble mean max temperatures• All over 12 hours (09:00 to 21:00 GMT)
18th Aug 2012: hottest day of year (32.4°C recorded in Suffolk)
Ensemble mean max temp
Chance >30°C
MOGREPS-UK18th Aug03:00 GMT run
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Wind products
MOGREPS-UK 8th Aug 21:00 GMT run
e.g. chance of light (<6mph) sustained winds at each hour over UK over Weymouth Bay
• Derived from hourly instantaneous winds at 10m• Sustained wind and wind gust• Thresholds: strong (> 20mph), light (< 6mph), Beaufort scale (> 12, 17, 29, 23 mph)• Areas: Whole UK, Weymouth Bay sailing venue
Jim Trice
© Crown copyright Met Office
Site-specific products
24 Olympic venues:All England Tennis Club WimbledonEarls CourtExcelGreenwich ParkHampton Court PalaceHorseguards ParadeHyde ParkLords Cricket GroundNorth Greenwich ArenaOlympic ParkThe MallThe Royal Artillery BarracksWembley ArenaWembley StadiumEton DorneyWeymouth And PortlandBrands HatchHadleigh FarmLee Valley White Water CentreCity Of Coventry StadiumMillennium StadiumOld TraffordSt James ParkHampden Park
© Crown copyright Met Office
Rowing Cosswinds
© Crown copyright Met Office
Feedback• “The Mogreps-UK products were extremely useful for
the Olympic forecasting at Weymouth” – Jim Trice, Met Office Olympic
forecaster
• Assisted use of Weymouth Bay forecasts
• Characteristics of 300m model were unknown - MOGREPS-UK provided confidence
• Chance of high temperatures useful for forecasting of sea breezes
• “I was especially impressed by the variety of products and by the clear explanations that accompanied each of the products.” – Beth Ebert, Research Program Leader,
Australian Bureau of Meteorology
• Over 25,500 web page visits
• Mean viewing time implies products were being used
© Crown copyright Met Office
Summary
• Delivered products from MOGREPS-UK that were
• Focussed on high-impact weather (high temporal and spatial resolution)
• Relevant to the general public, Olympic forecasters and LOCOG
• Presented and documented in an understandable and clear manner to the target audience
• Showcased cutting-edge science at the Met Office
• Demonstrated the utility of probabilistic, high resolution forecast products
© Crown copyright Met Office
Thanks for listening!