f. grazzini, forecast products users meeting 15-17 june 2005 severe weather forecasts f. grazzini,...
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F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
SEVERE WEATHER FORECASTS
F. Grazzini, F. Lalaurette
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
- EFI definition and properties
- Definition of extreme weather in the observations
- EFI Verifications results
- A case study
- Two new products for severe weather forecasting
OUTLINE
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
It is a normalised distance of an ensemble
forecast from a climate distribution
0=forecast distribution identical to the
climate one
1= forecast distribution is a perfect
outlier
EFI definition
http://www.ecmwf.int/products/forecasts/efi_guide.pdf
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
r proportion of outliers (Q100) in the forecast
0
0.2
0.4
0.6
0.8
1E
xtre
me
Fore
cast
Ind
ex v
alue
(1-r) forecast Q0(1-r) forecast Q50(1-r) forecast Q75(1-r) forecast Q90
EFI variations for bimodal distributionsFull lines: EFI
AD Dashed lines: EFI
3
EFI: a measure of anomaly and spread
Solid lines/current formulation, dashed lines pre 2003 formulation
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
EFI verification: the need of a local climatology
Climate Atlas of Europe (Météo-France)
The atlas contains monthly normals of temperature, precipitation, wind and sunshine duration for ~ 700 selected European stations. In addition statistical information for these parameters and for the occurrence of phenomena such as fog, thunderstorm, hail and snow are reported. The computation period is 1971-2000.
More information at http://www.eumetnet.eu.org/ECSN_home.htm
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
Extreme event if 24h TP > Tsh
Tsh=max(20,RRQ4/5)
RRQ4 = Upper quintile of monthly precipitation (per station, per month)
Using GTS synop 2622 “extreme” events were found during the period October 2003 – May 2005
Extreme event definition
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
38°N
48°N
58°N
68°N
22.0°W
22.0°W
2.0°W
2.0°W
18°E
18°E 38°E
38°E
20 - 25 25 - 30 30 - 50 50 - 70 70 - 100
Extreme precipitation thresholds
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
40°N40°N
60°N60°N
0°
0°
Ths: Max(20mm, 20pc)0 - 0.5 0.5 - 2 2 - 4 4 - 6 6 - 20
Frequency of extreme daily precipitation TP > Tsh
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1False Alarm Rate
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Pro
babi
lity
of D
etec
tion
ROC curves(Annual verification, Min=20mm or 20/100 th of Upper Monthly Quintile)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
6-30 18-42 30-54 42-66 54-78 66-90 78-102
90-114 102-126 114-138 ?
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Probability of False Detection
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Pro
babi
lity
of D
etec
tion
Modified ROC curves
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
6-30 18-42 30-54 42-66 54-78 66-90 78-102
90-114 102-126 114-138 ?
EFI verification: 221156 total events, 2622 extreme events
False Alarm RatioPOFD=F/(Z+F) FAR=F/(H+F)FC / OBS YES NO
YES H F
NO M Z
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1False Alarm Rate
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Pro
babi
lity
of D
etec
tion
ROC curvesProb(Annual veri fication, Min=20mm or 20/100 th of Upper Monthly Quinti le)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
36 72 120 ?
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Probability of False Detection
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Pro
babi
lity
of D
etec
tion
Modified ROC curves
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
36 72 120 ?
False Alarm Ratio
Verification of prob of TP > 20 mm/24h
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
EFI values to produce an even number of Hit and False Alarms
0
10
20
30
40
50
60
70
114-138
102-126
90-114
78-102
66-90 54-78 42-66 30-54
FC step
EF
I
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
80°S80°S
60°S60°S
40°S40°S
20°S20°S
0°0°
20°N20°N
40°N40°N
60°N60°N
80°N80°N
160°W
160°W
120°W
120°W
80°W
80°W
40°W
40°W
0°
0°
40°E
40°E
80°E
80°E
120°E
120°E
160°E
160°E
Frequency of EFI gt 0.6Surface: **Total precipitation index
Tuesday 7 October 2003 12UTC ECMWF Extreme Forecast Index (order = 0) VT: Monday 13 October 2003 06UTC t+(114-138)
0.5
2
3
5
20
Frequency of EFI > 0.6 Medium-Range
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
80°S80°S
60°S60°S
40°S40°S
20°S20°S
0°0°
20°N20°N
40°N40°N
60°N60°N
80°N80°N
160°W
160°W
120°W
120°W
80°W
80°W
40°W
40°W
0°
0°
40°E
40°E
80°E
80°E
120°E
120°E
160°E
160°E
Frequency of EFI gt 0.45Surface: **Total precipitation index
Tuesday 7 October 2003 12UTC ECMWF Extreme Forecast Index (order = 0) VT: Monday 13 October 2003 06UTC t+(114-138)
0.5
2
3
5
20
Frequency of EFI > 0.45 Medium-Range
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
80°S80°S
60°S60°S
40°S40°S
20°S20°S
0°0°
20°N20°N
40°N40°N
60°N60°N
80°N80°N
160°W
160°W
120°W
120°W
80°W
80°W
40°W
40°W
0°
0°
40°E
40°E
80°E
80°E
120°E
120°E
160°E
160°E
Frequency of EFI gt 0.6Surface: **Total precipitation index
Tuesday 7 October 2003 12UTC ECMWF Extreme Forecast Index (order = 0) VT: Friday 10 October 2003 06UTC t+(42-66)
0.5
2
3
5
20
Frequency of EFI > 0.6 Short-Range
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
0
0
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0
0
0 0
1
1 1
1
1 11
1
1
1
38°N
48°N
58°N
2.0°W
2.0°W
18°E
18°E 38°E
38°E
Surface: Total precipitation indexTuesday 9 November 2004 12UTC ECMWF Extreme Forecast Index (order = 0) VT: Monday 15 November 2004 06UTC t+(114-138)
0.4
0.5
0.6
0.7
0.7363
A case study: heavy precip between 1411 06UTC – 1511 06UTC
D+5
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
0
0
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0
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0 0
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0
0
0
0
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0
0
0
0
0
0
0 0
1
1 1
1
1 11
1
1
1
38°N
48°N
58°N
2.0°W
2.0°W
18°E
18°E 38°E
38°E
Surface: Total precipitation indexWednesday 10 November 2004 12UTC ECMWF Extreme Forecast Index (order = 0) VT: Monday 15 November 2004 06UTC t+(90-114)
0.4
0.5
0.6
0.7
0.7796
A case study
D+4
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
0
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0
0
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1
1 1
1
1 11
1
1
1
38°N
48°N
58°N
2.0°W
2.0°W
18°E
18°E 38°E
38°E
Surface: Total precipitation indexThursday 11 November 2004 12UTC ECMWF Extreme Forecast Index (order = 0) VT: Monday 15 November 2004 06UTC t+(66-90)
0.4
0.5
0.6
0.7
0.8
0.8463
A case study
D+3
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
0
0
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00
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1
1 1
1
1 11
1
1
1
38°N
48°N
58°N
2.0°W
2.0°W
18°E
18°E 38°E
38°E
Surface: Total precipitation indexFriday 12 November 2004 12UTC ECMWF Extreme Forecast Index (order = 0) VT: Monday 15 November 2004 06UTC t+(42-66)
0.4
0.5
0.6
0.7
0.8
0.9
0.9003
A case study
D+2
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
http://w3ec2.ecmwf.int/metops/efitest/
New global EFI multi-parameter map for anomalous weather
- A simultaneous (synoptic) view of the flow pattern and associated weather parameters can provide a better understanding of possible scenarios.
- EFI provides a concise and selective information about deviation of the forecast from the climate
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
HH
H
H
H
HH
H
H
H
LL
L
L
L
L
LL
-32
-24
-24
-16
-16
-16
-16-16-16
-16
-8 -8
-8-8
-8
-8
-8
-8
-8
0
0
0
00
0 00
0
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8
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88
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16
16 1616
16
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16
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1616
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1616
16
16
24
24
24
24
80°S80°S
60°S60°S
40°S40°S
20°S20°S
0°0°
20°N20°N
40°N40°N
60°N60°N
80°N80°N
160°W
160°W
120°W
120°W
80°W
80°W
40°W
40°W
0°
0°
40°E
40°E
80°E
80°E
120°E
120°E
160°E
160°E
VT: 200411141000 hPa Z ensemble mean and EFI values for 24h TP, wind gust and 2m temperature
Weather anomalies predicted by EPS: 20041109 12 UTC
warm extreme warm extreme cold cold windy extreme wind Heavy precip Extreme precip
Global EFI Map
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
H
L
L
40°W
40°W
0°
0° 40°E
40°E
VT: 200411141000 hPa Z ensemble mean and EFI values for 24h TP, wind gust and 2m temperature
Weather anomalies predicted by EPS: 20041110 0 UTC
warm extreme warm extreme cold cold windy extreme wind Heavy precip
Global EFI Map
D+5
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
H
H
H
L
L
40°W
40°W
0°
0° 40°E
40°E
VT: 200411141000 hPa Z ensemble mean and EFI values for 24h TP, wind gust and 2m temperature
Weather anomalies predicted by EPS: 20041111 0 UTC
warm extreme warm extreme cold cold windy extreme wind Heavy precip Extreme precip
Global EFI Map
D+4
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
H
H
L
L
8
16
32
40°W
40°W
0°
0° 40°E
40°E
VT: 200411141000 hPa Z ensemble mean and EFI values for 24h TP, wind gust and 2m temperature
Weather anomalies predicted by EPS: 20041112 0 UTC
warm extreme warm extreme cold cold windy extreme wind Heavy precip Extreme precip
Global EFI Map
D+3
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
H
H
H
L
L
L
88
8
40°W
40°W
0°
0° 40°E
40°E
VT: 200411141000 hPa Z ensemble mean and EFI values for 24h TP, wind gust and 2m temperature
Weather anomalies predicted by EPS: 20041113 0 UTC
warm extreme warm extreme cold cold windy extreme wind Heavy precip Extreme precip
Global EFI Map
D+2
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
0 mm 20 mm 40 mm 60 mm 80 mmThreshold (24h-acc [06-06])
0%
25%
50%
75%
100%
Pro
babi
lity
not
to
exce
ed t
hres
hold
Climate
66h (EFI0=68%)
90h (EFI0=69.9%)
114h (EFI0=73.2%)
138h (EFI0=63.8%)
Empirical Distribution Functions 42.4oN /25
oE
24h-acc precip forecast VP 14/11/2004 6UTC-15/11/2004 6UTC
Global EFI Map
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
Freak wave prediction
-It is important to detect possible deviation from linear theory of wave interaction (Gaussian distribution of surface elevation)
-In particular condition nonlinear interaction of waves became stronger (focussing). The distribution of surface elevation may deviate from the Normal with increase in probability of anomalous waves (compared to the median)
-Additional wave parameters characterizing extreme events have been introduced in to the system in October 2003: BFI and the wave spectra kurtosis
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
Freak wave prediction: kurtosis analysis
1037
1031
975
1000
1015
1025
995
995
1005
1005
1015
10151015
1015
1015
1015
1015
1015
1025
1025
1025
1025
1025
1025
1035
15.0m/s
80°W
80°W
40°W
40°W
ECMWF Analysis VT:Friday 15 April 2005 06UTC Surface: Wave spectral kurtosisECMWF Analysis VT:Friday 15 April 2005 06UTC Surface: mean sea level pressure/Surf: 10 mtr v
0.05
0.075
0.1
0.125
0.15
0.175
0.2
0.225
0.25
0.275
0.3
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
1039
1030
1025
976
1001
1012
1016
985
995
995
1005
1005
1015
1015
1015
1015
1015
1015
1025
1025
1025
1025
1025
1025
1025
1035
1035
15.0m/s
80°W
80°W
40°W
40°W
ECMWF Analysis VT:Friday 15 April 2005 12UTC Surface: Wave spectral kurtosisECMWF Analysis VT:Friday 15 April 2005 12UTC Surface: mean sea level pressure/Surf: 10 mtr v
0.05
0.075
0.1
0.125
0.15
0.175
0.2
0.225
0.25
0.275
0.3
Freak wave prediction: kurtosis analysis
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
1038
1033
975
1001
1012
1014
995
995
1005
1005
1015
1015
1015
1015
1015
1015
1015
1025
1025
1025
1025
1025
1025
1035
15.0m/s
80°W
80°W
40°W
40°W
Thursday 14 April 2005 00UTC ECMWF Forecast t+36 VT: Friday 15 April 2005 12UTC Surface: Wave spectral kurtosisThursday 14 April 2005 00UTC ECMWF Forecast t+36 VT: Friday 15 April 2005 12UTC Surface: mean sea level pressure/Surf: 10 mtr v
0.05
0.075
0.1
0.125
0.15
0.175
0.2
0.225
0.25
0.275
0.3
Freak wave prediction: kurtosis forecast T+36
F. Grazzini, Forecast Products Users Meeting 15-17 June 2005
A step forward towards an EFI validation against observations
Verification could provide useful guidance for calibration
EFI verification for daily precipitation : mixed feelings, however it seem to provide better results than probabilities.
Global multi-parameter EFI maps may be useful to provide a synoptic view of weather anomalies to users
Progress in wind induced ocean freak waves
Summary