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Improved Statistical Intensity Forecast Models:A Joint Hurricane Testbed Project Update
Mark DeMaria, NOAA/NESDIS, Fort Collins, COJohn A. Knaff, CIRA/CSU, Fort Collins, COJohn Kaplan, NOAA/AOML/HRD, Miami, FL
Presented at the Interdepartmental Hurricane Conference
March 22, 2006
Outline
• Current Status of SHIPS and the Rapid Intensity Index (RII)
• Project Goals– New decay model in SHIPS– Modified vertical shear calculation– Discriminant analysis version of the RII
• Progress and Plans for the 2006 Season– Additional SHIPS modifications from 2005
results
2005 Operational Version of SHIPS
• 16 basic predictors– atmospheric from GFS forecast fields– oceanic from Reynold’s weekly SST– climatology and persistence from ATCF input
• Correction for ocean heat content (Atlantic only) and GOES predictors – previous JHT project
• Adjusted SST from Joe Cione cooling algorithm – previous JHT project, Atlantic only
• New decay model formulation– Less decay over islands and narrow landmasses– current JHT project
SHIPS Skill in 2005
0
5
10
15
20
25
30
12 24 36 48 60 72 84 96 108 120
Forecast Interval (hr)
Imp
rov
em
en
t O
ve
r S
HF
5 (
%)
Atlantic
East Pacific
Impact of New Decay Model and Cione Ocean Cooling
(based on re-runs of 2005 Atlantic forecasts)
0.0
2.0
4.0
6.0
8.0
10.0
12.0
12 24 36 48 60 72 84 96 108 120
Forecast Interval (hr)
Pe
rce
nt
Imp
rov
em
en
t
New Decay Model
SST Cooling
New Decay and SSTCooling
Vertical Shear Evaluation
• Shear evaluated from GFS forecast along OFCI track
• Large annulus utilized – 200-800 km radius
• Proposed new method– Remove vortex from GFS fields– Test other averaging areas
• Smaller radii• Elliptical region aligned with storm motion (Stacy Stewart
method)
SHIPS Shear Calculation Region200 hPa Wind Wilma 24 Oct 2005 06 UTC
Impact of OFCI and GFS Track Mismatch96 h Forecast for Frances from 27 Aug 2004 12 UTC
850 hPa 200 hPa
G G
O O
G = GFS position O = OFCI Position
GFS Fields After Vortex Removal Procedure 96 h Forecast for Frances from 27 Aug 2004 12 UTC
G G
OO
850 hPa 200 hPa
G = GFS position O = OFCI Position
Additional Changes based on 2005 Season
• Add storm translation to MPI calculation– Wilma (2005), Florence (1994)
• Add 250 hPa temperature predictor for cold upper atmosphere, but low tropopause– Epsilon and Zeta (2005)
• Print recon variables for qualitative use– GRIP model sample too small
• Test forecast with more general predictive equation – Will be run after SHIPS run, but saved for evaluation
Storm Translational Speed and MPI
– Current version adds constant 12 kt to DK (1994) and WH (1997) formulas
– Acceleration not accounted for– Add fraction of translational speed from
Schwerdt formula (a = 1.5c0.63) to MPI– Improves fit to 1982-2005 sample
Hurricane Epsilon and Tropical Storm Zeta(motivation for 250 hPa T predictor)
Zeta 03 Jan 2006 1745 UTCMax Wind = 55 kt
SST = 24.3 oCT’(200 hPa) = -4.1oCT’(250 hPa) = -6.6oC
Epsilon 04 Dec 2005 1445 UTCMax Wind = 70 kt
SST = 21.7 oCT’(200hPa) = -1.8oCT’(250hPa) = -6.4oC
Recon and Additional GOES Predictors
• GOES and Recon Intensity Prediction (GRIP) Model– Part of previous JHT project
• 808 cases 1995-2004– 6554 for total SHIPS sample
• Significant new predictive information in recon data
• Independent tested on 2005 Atlantic forecasts• Improvement only at 12-24 hours• Developmental sample still too small
Error Reduction of SHIPS Model Fit
From Inclusion of Recon and Satellite Data
0
1
2
3
4
5
6
7
8
9
10
6 18 30 42 54 66 78 90 102
114
Forecast Interval (hr)
Var
ian
ce In
crea
se (
%)
ALL 5
OHC
GOES1
GOES2
RECON1
RECON2
-15
-10
-5
0
5
10
15
20
12 24 36 48 60 72 84 96 108 120
Forecast Interval (hr)
Per
cen
t Im
pro
vem
ent
Independent Coefficients
Dependent Coefficients
Intensification is favored with large symmetric tangential wind near the RMW, but small area-integrated KE
2005 EvaluationVariance Increase for Developmental Sample
0
2E+16
4E+16
6E+16
8E+16
1E+17
1.2E+17
20 40 60 80 100 120 140 160
Maximum Wind (kt)
Kin
etic
En
erg
y (J
)Katrina2 05
Ivan 04
Rita 05
Fran 96 Wilma 05
Isabel 03
Jeanne 04Floyd 99
Frances 04
Georges2 98 Georges1 98
Bonnie 98Lili 02
Opal 95Dennis 05
Bret 99
Bertha 96
Charley1 04
Erin1 95Charley2 04
Earl 98 Claudette 01
Erin2 95Katrina1 05
Danny1 97
Danny2Gaston 04
KE-5
KE-4
KE-3
KE-2
KE-1
KE-0
SS-0 SS-1 SS-2 SS-3 SS-4 SS-5
Max Wind vs. KE categories of 1995-2005 U.S. Landfalling Hurricanes
Generalized Prediction Equation
dV/dt = (t) Continuous form of SHIPS model
assumed constant over entire forecast intervale.g., V(96) = V(0) + t
Replace with generalized prediction equation
dV/dt = V - (V/Vmpi)nV
n=3, -1 = 26 hr, Vmpi from MPI formulaestimate (t) statistically.
Analytic Solution for Constant Vmpi and Vs = Steady State V = Vmpi(/)1/3
V/Vs = (Vo/Vs)et/[1 + (e3t-1)(Vo/Vs)3]1/3
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
0 0.5 1 1.5 2 2.5 3 3.5 4
t/k
V/V
s
Vo/Vs=1.6Vo/Vs=1.3Vo/Vs=1.0Vo/Vs=0.7Vo/Vs=0.4Vo/Vs=0.1
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
0 0.5 1 1.5 2 2.5 3 3.5 4
t/k
V/V
s
Vo/Vs=1.6Vo/Vs=1.3Vo/Vs=1.0Vo/Vs=0.7Vo/Vs=0.4Vo/Vs=0.1
0 0
Plans for 2006 SHIPS Model
• Operational Version– 16 basic predictors + OHC/GOES correction– New speed adjusted MPI– New 250 hPa T predictor– Cione SST cooling algorithm (pending JHT approval)– New decay formulation (pending JHT approval)– Recon info included on SHIPS output, but not included
in the prediction– Can also show forecast with generalized prediction
equation• Parallel version
– Modified shear calculation
Rapid Intensity Index
• Uses subset of SHIPS input most correlated with rapid intensity change
• Estimates probability of 25 kt increase in next 24 hours– Original version used 30 kt threshold
• Atlantic and east Pacific versions• Results included on SHIPS text output
RII Brier Skill Score 2004-2005
RII Improvements
• Original version used binary method– 0 or 1 depending on if predictor exceeded threshold
• Updated version scales predictors between 0 and 1
• Current project– Use discriminant analysis to determine optimal
weights for combining predictors– To be developed during J. Kaplan visit to CIRA April
10-14th – Will be evaluated on independent 2006 cases
Acknowledgments
• Thanks to the TPC and JHT support staff– Chris Sisko– Alison Krautkramer– Chris Lauer– Jim Gross– Michelle Mainelli