Presentation is loading. Please wait.

Presentation is loading. Please wait.

© Crown copyright Met Office MOGREPS-W First-guess Severe Weather Warnings for NSWWS Estimating Impact – a Risk tool.

Similar presentations


Presentation on theme: "© Crown copyright Met Office MOGREPS-W First-guess Severe Weather Warnings for NSWWS Estimating Impact – a Risk tool."— Presentation transcript:

1 © Crown copyright Met Office MOGREPS-W First-guess Severe Weather Warnings for NSWWS Estimating Impact – a Risk tool

2 © Crown copyright Met Office The New National Severe Weather Warning Service (NSWWS) Alerts/warnings based on likelihood and impact Alerts - issued more than 24 hours ahead Warnings - issued up to 24 hours ahead Regionally varying impact thresholds Alerts/warnings presented by shape areas on a map rather that just by county area

3 © Crown copyright Met Office ECMWF Operations Workshop, Nov 2011 Regional Impact Thresholds Wind Gust RegionsRainfall Regions

4 © Crown copyright Met Office ECMWF Operations Workshop, Nov 2011 Introduction to MOGREPS-W MOGREPS-R Grid-Point Probs ( 70mph) Severe Gales: 3 rd February 2011 DT: 06Z WED 02/02/2011 VT: 18Z THU 03/02/2011 MOGREPS-W Probability Severe Wind Gusts ( 70mph) Forecaster Issued Warnings of Severe Wind Gusts ( 70mph)

5 © Crown copyright Met Office ECMWF Operations Workshop, Nov 2011 Calibration of MOGREPS-W Verification of 40mph forecasts Reliability Diagram (T+33h to T+42h forecasts) Under-forecasting ~36mph forecasts might be best at forecasting 40mph events Forecast Thresholds All forecast thresholds are verified as if they are forecasting 40mph events September 2010 to February 2011 (6 month period)

6 © Crown copyright Met Office ECMWF Operations Workshop, Nov 2011 Impact-based MOGREPS-W Weather Impact Matrix High Medium Low Very Low LowMediumHigh 70mph80mph90mph Example of MOGREPS-W Wind Gust thresholds for the Highlands and Islands 1% 20% 40% 60% Example of MOGREPS-W probability thresholds Impact Likelihood

7 © Crown copyright Met Office ECMWF Operations Workshop, Nov 2011 MOGREPS-W Example Ex-hurricane Katia, 12 th Sep 2011 MOGREPS-W first guess wind gust warning. Note small area of Red (but not enough to justify widespread) Good agreement with warning issued by forecaster on Sunday morning (right)

8 © Crown copyright Met Office ECMWF Operations Workshop, Nov 2011 MOGREPS-W Example Heavy Rain on 24 th October 2011 Good agreement with warning issued by forecaster (below) 3h Rainfall 24h Rainfall MOGREPS-R p(24h-ppn>50mm) T+42 MOGREPS-G p(24h-ppn>50mm) T+48


Download ppt "© Crown copyright Met Office MOGREPS-W First-guess Severe Weather Warnings for NSWWS Estimating Impact – a Risk tool."

Similar presentations


Ads by Google