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Verification of model wind structure and rainfall forecasts for 2008 Atlantic storms. HFIP Hurricane Diagnostics and Verification Workshop NHC, Miami, FL 04 May 2009. Tim Marchok NOAA / GFDL. Collaborators: Rob Rogers (NOAA / AOML / HRD) Bob Tuleya (NCEP/EMC & Old Dominion Univ.) - PowerPoint PPT Presentation
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Verification of model wind structure and rainfall forecasts for 2008 Atlantic storms
Tim MarchokNOAA / GFDL
Collaborators: Rob Rogers (NOAA / AOML / HRD)
Bob Tuleya (NCEP/EMC & Old Dominion Univ.)
Mark Powell (NOAA / AOML / HRD)
HFIP Hurricane Diagnostics and
Verification Workshop
NHC, Miami, FL
04 May 2009
Motivation
• Inland flooding from TC rainfall accounts for a significant percentage of deaths from U.S. landfalling TCs.
• Storm size / structure has a major impact on the amount of damage at landfall.
…both aspects have only recently begun to receive attention in terms of model evaluation
Outline
• Rainfall validation & techniques
• Application of TC QPF validation techniques to 2008 U.S. landfalling storms
• Development of model wind structure validation techniques
• Application of wind structure validation techniques to 2008 Atlantic TCs
• Rainfall patterns
• Rainfall mean & volume
• Extreme amounts
Rainfall validation: What to focus on?
The TC track: An anchor for QPF validation
GFDL
NAMGFSR-CLIPER
HWRFStage IV
Example: Hurricane Gustav 72-h total rainfall
2008 Landfalling Storms
Rainfall Patterns
20052008Equitable Threat Scores
Pattern Correlations: GFS (r = 0.78)
HWRF (r = 0.60)
GFDL (r = 0.53)
NAM (r = 0.52)
R-CLIPER (r = 0.51)
(2008)
Mean Rainfall
Rainfall volume
2008 2005
Comparison of rain volume bias by model
2008 Landfalling Storms
50% level
Difference between obs
rain value and fcst rain value at 50% level determines
index
Track-relative rain flux analyses
Rain volume: Rain flux in select bands
0–100 km
300-400 km
GFDL, HWRF GFS, NAM
Skill Indices: Pattern Matching
Pattern Matching (2005)
0.44
0.48
0.71
0.59
0 0.2 0.4 0.6 0.8 1
RCLIP
NAM
GFS
GFDL
2008 2005
• GFS performs the best in both samples
• All models have skill relative to R-CLIPER
Pattern Matching (2008)
0.40
0.48
0.78
0.52
0.50
0 0.2 0.4 0.6 0.8 1
RCLIP
NAM
GFS
HWRF
GFDL
Skill Indices: Mean / Volume
Volume (2005)
0.72
0.75
0.68
0.72
0 0.2 0.4 0.6 0.8 1
RCLIP
NAM
GFS
GFDL
2008 2005
Mean / Volume (2008)
0.36
0.80
0.79
0.32
0.70
0 0.2 0.4 0.6 0.8 1
RCLIP
NAM
GFS
HWRF
GFDL
Skill Indices: Extreme Amounts
Extreme Amounts (2005)
0.62
0.76
0.77
0.57
0 0.2 0.4 0.6 0.8 1
RCLIP
NAM
GFS
GFDL
2008 2005
• GFDL overforecasts the large amounts, HWRF underforecasts them, resulting in comparable indices
• GFS performs best despite lowest resolution
Extreme Amounts (2008)
0
0.56
0.82
0.62
0.61
0 0.2 0.4 0.6 0.8 1
RCLIP
NAM
GFS
HWRF
GFDL
Rainfall Summary
• Validation techniques address unique TC rainfall attributes:Pattern matchingRainfall volumeExtreme amounts
• TC QPF skill indices for operational forecast evaluation
• GFS most skillful in 2008 (similar to 2005)
Outline
• Rainfall validation & techniques
• Application of TC QPF validation techniques to 2008 U.S. landfalling storms
• Development of model wind structure validation techniques
• Application of wind structure validation techniques to 2008 Atlantic TCs
The importance of near-surface wind structure
Area_TSKatrina
Area_TSCharley
= Factor of 9
Focus is on continuous / homogeneous methods
• Distribution of WindsFractional areal coveragePDFs of the winds
• Radial StructureEarth-relative profilesStorm motion-relative profilesRadius of max winds
• Storm Destructive Potential IKE, SDP, WDP (Powell and Reinhold
2007)
• Others?
Cases included in study…
Distribution: Fractional Areal Coverage (34-kt winds)
Storm- sample
average at tau=00h
NW
SW SE
NE
Distribution: Fractional Areal Coverage (34-kt winds)
Storm- sample
average at tau=48h
NW
SW SE
NE
Distribution: Fractional Areal Coverage (64-kt winds)
Storm- sample
average at tau=00h
NW
SW SE
NE
Distribution: Fractional Areal Coverage (64-kt winds)
Storm- sample
average at tau=48h
NW
SW SE
NE
Radial profiles of the wind (all cases)
NW
SW SE
NE
Tau= 00h
Radial profiles of the wind (all cases)
NW
SW SE
NE
Tau= 48h
Radial profiles of the wind (Hurricanes only)
NW
SW SE
NE
Tau= 00h
Radial profiles of the wind (Hurricanes only)
NW
SW SE
NE
Tau= 48h
Radius of Maximum Winds
Forecasts of Integrated Kinetic Energy
GFDL Ike Intensity Forecasts HWRF Ike Intensity Forecasts
Max
Win
d (k
ts)
Max
Win
d (k
ts)
IKE
(T
J)
IKE
(T
J)
GFDL Ike IKE (V>18 m/s) Forecasts HWRF Ike IKE (V>18 m/s) Forecasts
Forecasts of Integrated Kinetic Energy
Wind Structure Summary
• Methods complementary to wind radii validation
• Focus on various aspects of wind fieldDistributionRadial structure IKE / Storm destructive potentialOthers…?
• Some biases already evident