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Early warnings for severe weather. Tim Hewson. Severe weather in Europe. Structure of Talk. 1. Cyclone products ( nwmstest.ecmwf.int/products/forecasts/ cdb / ) Brief overview – principles, identification and tracking

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early warnings for severe weather

Early warnings for severe weather

Tim Hewson

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

slide2

Severe weather in

Europe

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

structure of talk
Structure of Talk
  • 1. Cyclone products (nwmstest.ecmwf.int/products/forecasts/cdb/)
    • Brief overview – principles, identification and tracking
    • The products - improvements made in the last year (based partly on direct user feedback) and future plans
    • Storm examples from winter 2009/10
    • Verification of cyclone handling during winter 2009/10 – deterministic and 3 EPS systems
    • How can the forecaster make use of verification statistics?
  • 2. EFI products
    • Brief overview
    • Issues related to the model climate, and future plans
  • 3. Summary

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

1 cyclonic features
1. Cyclonic Features

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

a principles
A. Principles
  • Provision of warnings of severe weather is a key task for NMS’s, and assisting with this goal is a key target for ECMWF
  • There are direct connections between severe (or extreme) weather and synoptic features (e.g. fronts, frontal waves, lows), which forecasters make daily use of
  • So automating feature identification in a manner consistent with operational practice provides:
      • 1. A range of EPS-based real-time tools for assisting the forecaster in warning of adverse weather (Products)
      • 2. A means by which real-time forecasts of adverse weather can be verified, by proxy, by comparing the forecast features with features identified in model analyses (Verification). This proxy approach nicely circumvents verification problems related to surface data availability and reliability. We verify as much over data sparse regions, including the oceans; intrinsically this (i) increases the number of severe events we verify, making results more reliable, and (ii) normalises data density.

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

b identification of cyclonic features
B. Identification of Cyclonic Features
  • Overall methodology is based around this conceptual model of extra-tropical cyclone development (but is not constrained by it):

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

example snapshot cyclonic features mslp objective fronts

Diminutive Wave (weak)

Barotropic Low

Frontal Wave (weak)

Frontal Wave

Diminutive Wave

Example SnapshotCyclonic Features, Mslp, Objective fronts

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

c tracking cyclonic features
C. Tracking cyclonic features
  • In tailoring algorithms special attention was paid to the evolutionary behaviour of windstorm-generating cyclones. Typical characteristics catered for include:
    • Originate on fronts – frontal wave or diminutive wave
    • Rapid movement (beneath strong upper level jets)
    • Rapid decelleration (in the jet’s left exit)
    • Can be very small-scale
    • Can be very short-lived (<24h)
  • All details of the methodology can be found in Hewson and Titley, 2010 (Met Apps, now in press)

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

d forecast products
D. Forecast Products

Based on the 50-member ensemble + control and deterministic runs

i) Feature-related

ii) Track-related

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

i feature related products
i) Feature-related products

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

snapshot of synoptic feature chart
Snapshot of Synoptic Feature Chart

NEW - 1000-500mb thickness lines added

NEW - Deterministic run now available

Single forecast run

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

fronts spaghetti plot
Fronts Spaghetti Plot

EPS + Control + Deterministic

NEW - Deterrministic run added

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

fronts spaghetti plot1
Fronts Spaghetti Plot

EPS + Control + Deterministic

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

postage stamps various options
Postage stamps (various options)

NEW - Deterministic run added

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart feature type
Dalmatian Chart (feature type)

NEW - Deterministic run added

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart mslp

NEW

Dalmatian Chart (mslp)

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind 300km radius

NEW

Dalmatian Chart (max 1km wind, 300km radius)

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart 1000 500mb thickness

NEW

Dalmatian Chart (1000-500mb thickness)

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind 600km radius

NEW

Dalmatian Chart (max 1km wind, 600km radius)

52 forecast runs (EPS + Control + Deterministic)

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

revised feature chart with ppn

Soon

Revised Feature chart (with ppn)

(shading shows rain, sleet, snow totals; thresholds 2 / 8 / 20 / 50mm in 12hours)

Single deterministic forecast run

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

clickable dalmatian chart

Soon

Clickable dalmatian chart
  • Enables the user to select a ‘representative member’ or an ‘extreme member’ (prototype in place), or just examine many different members
  • User feedback required on what effect the users would like to see “hovering” and “clicking” have…
  • At present hovering shows just the EPS member, clicking brings up the corresponding synoptic chart

Live Demo

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

planned
Planned:
  • Dalmatian plots that show the temporally (-6 to +6h) and areally (300km radius) integrated ppn totals (rain and/or snow) within rings around each cyclonic feature
  • Precipitation is thereby associated with features (as in forecasting)
  • This will extend application into warnings of heavy rainfall, flooding, snowfall, blizzards, etc
  • Feature plume diagrams may also show this as an attribute
  • Distinction may be made between rain and snow
  • Dalmatian chart that shows rate of deepening in previous or upcoming 12 hours (by blending with feature tracking attributes)

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

ii track related products
ii) Track-related Products

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

interactive selection of specific weather systems from t 0
Interactive selection of specific weather systems from T+0

User clicks on any spot at T+0 (= cyclonic feature) to see how that feature evolves in the EPS

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

slide25

NEW - Deterministic run added

User can click on track plot, to animate

‘Plume’ diagrams

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

starburst animation

NEW - Deterministic run added

Starburst animation

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

strike probability plot for feature tracks moderate intensity features 34kt threshold
Strike Probability Plot – for feature tracks- ‘moderate intensity features’ (34kt threshold)

(EPS only)

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

strike probability animations 15 day three thresholds dt 12z 25 2 2010
Strike Probability Animations (15 day)- three thresholds (DT 12Z 25/2/2010)

51 forecast runs (EPS only)

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

strike prob postage stamps

NEW

Strike prob postage stamps

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

strike prob postage stamps1

NEW

Strike prob postage stamps

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

slide31

NEW

Links back to main forecast products web page

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

ideas for the future
Ideas for the future:
  • Vectors may be added to denote an “average” direction of movement for features on the strike prob plots
  • Single lines may be added to show tracks in the deterministic run
  • As well as strike probs based on wind thresholds, the new precipitation attribute could be used, separately, to define strike probs for systems producing substantial areally-integrated 12h rainfall (above set thresholds), and/or snowfall – “track of rainstorms”

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

tracking improvements
Tracking improvements ?
  • Though performance of the tracking system compares very favourably with other systems, very occasionally some issues arise – e.g. a feature may not be tracked to the next frame time when it should be
  • There is scope for making subtle adjustments, based on matching distances, to the tracking parameters
    • in particular the appropriateness of the steering wind assumption needs checking – is 60% of the 500mb wind appropriate ?
    • could this be changed depending on system type ?
    • subjective evidence suggests that this is appropriate for frontal waves, but may be less appropriate for barotropic lows
    • identical changes would of course be made to tracking of analysed features (for verification)

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

e windstorm examples
E. Windstorm Examples

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

portugal storm example xola
Portugal Storm example – “Xola”

“Micro-storm”

23 Dec 2009

00 UTC

23 Dec 2009

04 UTC

967

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

synoptic animation
Synoptic animation

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

24h lead plumes
24h lead plumes

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

12h lead plumes
12h lead plumes

Observed

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

portuguese windstorm xola
Portuguese Windstorm – “Xola”
  • The ECMWF forecast system failed to capture the full intensity of the storm, partly because of its small scale
  • However the cyclone tracking facility did provide some clear pointers to:
    • The potential for rapid intensification
    • The feature being small scale
    • High uncertainty (associated in part with a strong upper level jet – akin to Lothar in France in Dec 1999)

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

300mb isotachs and mslp analysis 00z 23 12 09
300mb isotachs and mslp – analysis – 00Z 23/12/09

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

xynthia 27 28 feb 2010
“Xynthia” – 27-28 Feb 2010

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

synoptic animation1
Synoptic animation

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind in 600km radius
Dalmatian chart – max 1km wind in 600km radius

8 days

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind in 600km radius1
Dalmatian chart – max 1km wind in 600km radius

7.5 days

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind in 600km radius2
Dalmatian chart – max 1km wind in 600km radius

7 days

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind in 600km radius3
Dalmatian chart – max 1km wind in 600km radius

6.5 days

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind in 600km radius4
Dalmatian chart – max 1km wind in 600km radius

6 days

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind in 600km radius5
Dalmatian chart – max 1km wind in 600km radius

5.5 days

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind in 600km radius6
Dalmatian chart – max 1km wind in 600km radius

5 days

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind in 600km radius7
Dalmatian chart – max 1km wind in 600km radius

4.5 days

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind in 600km radius8
Dalmatian chart – max 1km wind in 600km radius

4 days

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind in 600km radius9
Dalmatian chart – max 1km wind in 600km radius

3.5 days

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind in 600km radius10
Dalmatian chart – max 1km wind in 600km radius

3 days

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind in 600km radius11
Dalmatian chart – max 1km wind in 600km radius

2.5 days

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind in 600km radius12
Dalmatian chart – max 1km wind in 600km radius

2 days

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind in 600km radius13
Dalmatian chart – max 1km wind in 600km radius

1.5 days

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind in 600km radius14
Dalmatian chart – max 1km wind in 600km radius

1 day

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind in 600km radius15
Dalmatian chart – max 1km wind in 600km radius

0.5 days

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

dalmatian chart max 1km wind in 600km radius16
Dalmatian chart – max 1km wind in 600km radius

0 days

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

xynthia windstorm
“Xynthia” Windstorm
  • The ECMWF forecast system gave pointers to the potential for a major windstorm from at least 8 days out. This is clearly visible on the dalmatian plots
  • As the time of the storm approached the IFS solutions tended to converge, with regard to both track and intensity
  • The most extreme set of solutions arose at a lead of 4.5 days, including some truly phenomenal windstorms
    • So with regard to wind strength it seems this storm could have been much worse…

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

f track related products and verification
F. Track-related products and Verification

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

verification for different leads
Verification for different leads
  • At short leads we verify ‘plume diagrams’, focussing on the behaviour of specific cyclonic features in the EPS. A wide range of statistics can be obtained (position-related, intensity related, for EPS, for Det, etc) – comparable to what is done for tropical storms.
  • At longer leads (especially), where cross-referencing of features between members becomes increasingly problematic, we verify ‘storm track strike probabilities’, to cater for every feature that reaches a pre-defined severity threshold (this is intrinsically EPS specific, though deterministic runs could be addressed too).
  • Statistics will be from an intercomparison period in early winter 2009/10 (~Nov 25th – Jan 10th); using the ECMWF Operational suite, the ECMWF E-suite (trial version of the new hi-res suite), and the Met Office MOGREPS EPS system (global version).

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

exampleof forecastplumes
Exampleof forecastplumes

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

slide64

Forecastplumes with verifying data

added(automated process -uses tracks from deterministic run analysis sequence)

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

6 weeks of verification winter 2009 10

Deterministic beats control

  • Control beats feature mean until day 3
  • Deterministic beats feature mean until day 3.5
  • Single EPS member clearly worse throughout
6 weeks of verification – winter 2009/10

Deterministic

Control

Ensemble ‘Feature Mean’

Ensemble member 25

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

how might the forecaster use these results
How might the forecaster use these results ?
  • To decide whether to favour the EPS feature mean or Deterministic..
  • At day 4 on average the EPS feature mean position is slightly more accurate than the deterministic
  • Therefore a minimum error forecast would be based on the EPS feature mean, or at least give more weight to this
  • In future we can test objectively how and whether blending two such solutions can reduce average error

Forecast for deep low at 00Z Sat this

week, from 00Z Tue

Deterministic

EPS feature mean

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

strike probability verification
‘Strike Probability’ verification
  • Various measures computed:
    • Brier Skill Score (assuming sample is climate, no geographical variation), and Brier Score decomposition
    • ROC curves, ROC area
    • Reliability (high for all thresholds)

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

example of strike probability plot storms category
Example of Strike Probability Plot - ‘storms’ category

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

brier skill score 3 categories
Brier Skill Score, 3 categories

Operational

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

brier skill score 3 categories1
Brier Skill Score, 3 categories

Hi-res trial

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

comparing centres
Comparing centres

ECMWF

O-suite

Operational

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

slide72

Comparing centres

Met Office

MOGREPS

Identical period

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

cyclonic feature strike probs brier skill score summary
Cyclonic Feature Strike Probs - Brier Skill Score Summary
  • Clear lead time gain in Hi-res trial suite vsOper suite, for the two weaker categories
    • ~ 12h at day 2, ~ 24h day 8 onwards
  • Step change in skill at day 10 (presumably relates to model resolution change)
  • ‘Storm’ category slightly better in E-suite at longer leads but slightly worse at short leads
    • Several possible reasons for degradation – sampling may be one issue
    • Suggestions from two cases of somewhat greater refinement in the O-suite handling (eg higher probs at longer leads in right areas)
    • One for continued monitoring !
  • ECMWF EPS outperforms MOGREPS up to about day 10.

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

2 efi related products
2. EFI-related products

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

efi and cdf products
EFI and CDF products
  • Standard EFI (Extreme Forecast Index) products were augmented in summer last year by a “clickable EFI” facility
  • Whilst feedback on this has been very positive we are continually striving to improve the output
  • Here will illustrate a problem related to the hindcast climatology, and demonstrate possible ways forward
  • From a user-perspective awareness of any current limitations is also very important…
  • First a quick EFI recap…

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

clickable efi web interface
Clickable EFI web interface

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

efi derivation
EFI derivation
  • EFI is based on CDFs – or “Cumulative Distribution Functions”
  • Users may be more familiar with PDFs – Probability Density Functions
  • CDFs and PDFs are just different ways of representing a distribution, of a set of forecasts or hindcasts, in probability space
  • First we illustrate the CDF-PDF connection, then briefly re-visit how the EFI is calculated..

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

how do cdfs and pdfs relate

PDF (probability density function)

Prob (interval)

Parameter value

How do CDFs and PDFs relate ?

CDF

Prob (threshold)

Parameter value

  • The PDF (y-axis) value equals the slope of the CDF
  • Steeper CDF = narrower PDF = higher confidence
  • A step in the CDF means a bimodal PDF

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

efi and the m climate
EFI and the “M-Climate”
  • EFI is based on comparing a climatological CDF (from model hindcasts, which we call the “M-Climate”) with the forecast CDF derived from the EPS
  • Example that follows is for temperature, but same principle is used for precipitation and wind (though in these latter cases CDF’s generally have a different shape)…

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

slide80

Represented by pink

lines below

1

EFI takes no direct

account of any EPS

members beyond

M-climate max

Cumulative

M-climate

EPS

p

EFI

Ff (p)

1

And so can be

sensitive to the

value of that

maximum

0.5

(rank/n) =

0

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

precipitation cdfs for washington dc 6 feb 2010 a record snowfall event
Precipitation CDFs for Washington DC – 6 Feb 2010- a record snowfall event

All members appear to be above the M-Climate, yet EFI < 100% ??

M-Climate on standard web products is for the 24-48h lead

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

m climate is a function of lead time washington dc 6 feb
M-Climate isa function of lead time - Washington DC, 6 Feb

2

5

3

6

4

1

Maximum

M-Climate for different leads,

for ppn totals

mm in 24h

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

precipitation cdfs for washington dc 6 feb 2010
Precipitation CDFs for Washington DC – 6 Feb 2010

M-Climate on standard web products is for the 24-48h lead

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

m climate extremes 6 feb
M-Climate extremes, 6 Feb
  • Random occurrence of a very rare event within the hindcastscan alter the M-Climate, most notably the 100th percentile, in a way that is not indicative of bias in the forecast system – we can call this “the hindcast sampling error”

30 40 50 70 100 150 200

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

hindcast sampling error
Hindcast Sampling Error
  • When present this can have an adverse impact on EFI ‘integrity’
  • So in real-time forecasts, run-to-run changes in EFI, for a given day, can become a little misleading, as we have seen
  • As a general guide this will be especially true in instances where EFI computation is sensitive to the M-Climate tail, which in turn is when both the following are satisfied:
    • forecast CDFs are relatively vertical (=narrow PDF), as commonly occurs at shorter leads (when confidence is usually higher)
    • when a relatively rare event is expected, because the 100th percentile value then carries much more “weight” in the EFI computation
  • Such problems are in general more likely to occur with rainfall totals and wind gusts than with temperature extremes
  • Tropical cyclones in the hindcasts are likely to cause particular problems

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

addressing hindcast sampling error
Addressing hindcast sampling error
  • Considerable work went into designing the current hindcast system, the strategy being to make best use of available resources to meet the needs of the EFI, the monthly forecast system, etc..
  • Inevitably there are resource-related limitations of any approach, and as we have seen, fluctuations, with lead time, in the tails of M-climate are one current problem
  • We would like to remove any of those fluctuations that are not directly indicative of model bias (ie the ‘hindcast sampling error’)
  • Running far more hindcasts is not an option
  • Application of extreme value theory (see Fernando’s talk later) may provide one route to resolving this
  • Applying a linear fit, with lead, to the percentile values, and redefining the M-climate to be based instead on the fitted values might be another option (though this assumes bias can only vary linearly)
  • Or…?

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

current vs linear fit to 100 th percentile
Current vs linear fit to 100th percentile

6

5

4

3

2

1

2

5

3

6

4

1

Maximum

M-Climate for different leads

mm in 24h

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

precipitation cdfs for washington dc 6 feb 20101
Precipitation CDFs for Washington DC – 6 Feb 2010

85%

70%

Estimated changes in two of the EFI values

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson

3 summary
3. Summary
  • Sophisticated tools for identifying and tracking cyclonic features have been applied to IFS output and are now providing many web-based tools for the forecaster. The aim is to provide assistance with severe weather prediction.
  • This year developments have centred on increasing the utility of these tools – in particular adding deterministic run data, and expanding the range of ‘dalmatian plots’
  • Operational implementation is expected in the next few months (although product availability and timeliness are unlikely to change much)
  • Future plans include adding a precipitation attribute, as well as clickable dalmatian charts, which should greatly increase product utility
  • Verification code has also been further developed and implemented; this shows clear improvements in cyclone handling in the hi-res system introduced late in January, and provides the forecaster with useful information regarding typical cyclone-related errors
  • Clickable web-based EFI charts are now “operational”. Hindcast sampling issues can occasionally affect the M-Climate; this aspect has been demonstrated, for the benefit of users, with potential solutions identified

FPU meeting 9 June 2010 “Early warnings for severe weather“ Tim Hewson