© ECMWF October 12, 2015

Update on ECMWF forecast performance

Thomas Haiden, Martin Janousek

October 29, 2014

Contents

2

• Upper-air performance

• Surface parameters

• Model upgrade 2016 (cycle 41r2)

• High-impact weather

• Scale-dependence of skill

October 29, 2014

Upper-air forecast skill

3

October 29, 2014

Upper-air forecast skill

4

ERA-Interim

HRES

October 29, 2014

Upper-air forecast skill

5

HRES - ERA-Interim

October 29, 2014

Model intercomparison

6

October 29, 2014

Forecast skill: vertical correlation

7

Geer (2015)

← 500 hPa height

850 hPa temperature →

October 29, 2014

Upper-air ensemble forecast skill

8

𝐶𝑅𝑃𝑆𝑆 = 1 −𝐶𝑅𝑃𝑆𝐸𝑁𝑆𝐶𝑅𝑃𝑆𝐶𝐿𝐼𝑀

60%

40%

25%

October 29, 2014

Upper-air ensemble forecast skill

9

CRPS

D+4

D+6

D+8

October 29, 2014

Wave forecast: verification against buoys

10

Wave height Wind speed

October 29, 2014

Wave height – model intercomparison

11

DJF 2015-16

October 29, 2014

10 m wind speed

12

SDEV

BIAS

D+3

October 29, 2014

2 m temperature

13

SDEV

BIAS

D+3

October 29, 2014

2 m temperature bias at 00 UTC (DJF)

14

Winter 2014-15 Winter 2015-16

October 29, 2014

Precipitation

15

Simbach, Germany, 2 June 2016

October 29, 2014

Performance during individual events

16

Large-scale events that actually happened

October 29, 2014

Headline score for HRES precipitation: SEEPS

17

Skill in discriminating

between

• Dry

• Light

• Moderate-to-

heavy

Adapted to local

climatology

HRES

October 29, 2014

HRES precipitation

18

Skill in discriminating

between

• Dry

• Light

• Moderate-to-

heavy

Adapted to local

climatology

ERA-Interim

October 29, 2014

HRES precipitation

19

Skill in discriminating

between

• Dry

• Light

• Moderate-to-

heavy

Adapted to local

climatology

DIFFERENCE

October 29, 2014

HRES precipitation – other centres

20

Skill (ETS)

Frequency

bias

D+5

Extra-tropics

Thr=10mm/24h

October 29, 2014

ENS precipitation

21

CRPSS=10%

October 29, 2014

ENS precipitation – other centres

22

October 29, 2014

Model upgrade in March 2016 (Cycle 41r2)

23

Nhem Shem Tropics Europe N-Atl N-Amer N-Pac E-Asia Aust/NZ Arctic Antarctic

Upper-air: improvements 2-3%

Surface: up to 5% in the medium range

October 29, 2014

Improvements in surface parameters

24

uniform resolution

HRES 10 m wind speed ENS 2 m temperature

October 29, 2014

High-impact weather

25

Monitoring of forecast skill for extremesTropical cyclones

2m temperature 10m wind speed

24-h precipitation

Extreme forecast index (EFI), D+4

D+3

D+5

Position

Intensity

Speed

Position

spread/error

Heavy precipitation

ECMWF Newsletter 144 (Summer 2015)

Largest gains in skill at days 4-7

October 29, 2014

EFI for severe convection (CAPE, CAPESHEAR)

28

Verification against severe weather reports

(tornadoes, large hail, severe wind gusts)

Summer 2015, United States

65%

35%

October 29, 2014

29

Forecast skill horizon (schematic)

ECMWF Newsletter No. 145 (2015)

October 29, 2014

30

Forecast skill horizon: 500 hPa geopotential

Buizza and Leutbecher (2015)

Temporal averaging →

Spatial

averaging

↓

T120 T30

T7

October 29, 2014

Precipitation verification against gridded data (NEXRAD)

31

Frequency bias (Oct 2014 – April 2015) Fractions skill score FSS (April - Aug 2014)

16km16km

…1 2 n

i

j

Forecast Fn=5/25

Observed On=3/25

MSEn = (Fn-On)2

FSS concept

October 29, 2014

32

Total cloud cover forecast skill

ECMWF Newsletter No. 143 (2015)

October 29, 2014

Summary

33

• Upper-air performance continues to increase

• ECMWF maintains overall lead among global centres

• Challenge of 2 m temperature biases

• Significant improvements from Cycle 41r2

• Increased focus on verification of high-impact weather

• Forecast skill horizon: scale-dependent predictability

October 29, 2014

34

Deadline: 31 October 2016

Price: Invited keynote and paid attendance at the

7th International Verification Methods Workshop in

May 2017 (Berlin, Germany)

October 29, 2014

Model intercomparison DJF

35

October 29, 2014

Potential economic value of extreme wind forecasts

36

moderately

strong

extreme

extreme and

large-scale

see also ECMWF Newsletter No. 139 (2014)

October 29, 2014

EFI for severe convection (CAPE, CAPESHEAR)

37

Verification against severe weather reports

(tornadoes, large hail, severe wind gusts)

Summer 2015, United States

65%

35%

I. Tsonevsky (2016)