Transcript Evolution of the Relationship Between Forecasters and Numerical Models 

Evolution of the Relationship Between
Forecasters and Numerical Models
Over the Last 50 Years
 Model-driven evolution
 Support-system-driven
evolution
 Emerging forecaster-model
relationships
 The result
Symposium on the 50th Anniversary of
Operational Numerical Weather Prediction
June 16, 2004
1
NCEP Vision: First Choice – First Alert – Preferred Partner
Jim Hoke
Director, HPC
Director, OPC
Numerical modeling progress
has driven the evolution of the
human role in weather prediction
• Forecasts were produced by hand, based heavily on
forecaster experience, rules of thumb, and intuition
• Forecasters began using numerical forecasts as one tool
to enhance their own forecast skill
• the numerical forecasts added
value to the human forecasts
• As their skill improved, numerical
forecasts increasingly supplanted
human forecasts
• The forecaster role now is viewed
more as adding value to the
numerical forecasts
2
NCEP Vision: First Choice – First Alert – Preferred Partner
HPC QPF verification
1-inch threat score
3
NCEP Vision: First Choice – First Alert – Preferred Partner
HPC QPF verification vs. the models
Day 1, 1 inch
4
NCEP Vision: First Choice – First Alert – Preferred Partner
HPC medium-range Tmax verification
% reduction in Mean Absolute Error over MOS
(by year) (adjusted stations only)
5
NCEP Vision: First Choice – First Alert – Preferred Partner
Support-system progress
has also driven the evolution of the
human role in weather prediction
• Initially at weather centers, a small number of forecasters
was supported by a large number of technicians
• Grease pencils, acetates, light tables, plotters,
and scanners
• Limited access to observations
• Few models, forecast fields, output times, colors
6
NCEP Vision: First Choice – First Alert – Preferred Partner
Support-system progress
has also driven the evolution of the
human role in weather prediction (continued)
• Now weather centers are heavily staffed by
forecasters
• Sophisticated meteorological workstations
• Rapid access to huge volume of observations
• Many models & ensembles, many forecast fields,
many output times, many colors
7
NCEP Vision: First Choice – First Alert – Preferred Partner
Estimated HPC meteorological
technician & reproduction-equipment
technician staffing by year
year
1970
1975
1980
1986
1990
met
techs
97
82
47
28
21
1994
1995
1997
12
9
4
7
6
0
19
15
4
2002
3
0
3
8
repro
techs total
15
112
14
96
14
61
11
39
8
29
NCEP Vision: First Choice – First Alert – Preferred Partner
“Emerging” relationship of
forecasters and numerical models
 Enhancing objective surface analyses, esp. regarding
mesoscale features and over the oceans
 Providing oversight of observation, analysis, and
numerical deterministic & probabilistic forecast systems
An abnormal transit?
9
NCEP Vision: First Choice – First Alert – Preferred Partner
Providing oversight (continued)
10
NCEP Vision: First Choice – First Alert – Preferred Partner
“Emerging” relationship of
forecasters and numerical models
 Enhancing objective surface analyses, esp. regarding
mesoscale features and over the oceans
 Providing oversight of observation, analysis, and numerical
deterministic and probabilistic forecast systems
 Determining most probable forecast states, their likely
spread, and uncertainty of the forecasts (using ensembles)
 Determining modeling system deficiencies
(deterministic & probabilistic)
 Evaluating proposed model
changes
 Providing model interpretation
for customers
11
NCEP Vision: First Choice – First Alert – Preferred Partner
Providing model interpretation
for customers (continued)
12
NCEP Vision: First Choice – First Alert – Preferred Partner
“Emerging” relationship of
forecasters and numerical models
 Enhancing objective surface analyses, esp. regarding
mesoscale features and over the oceans
 Providing oversight of observation, analysis, and
numerical deterministic and probabilistic forecast
systems
 Determining most probable forecast states, their likely
spread, and uncertainty of the forecasts (using
ensembles)
 Determining modeling system deficiencies (deterministic
& probabilistic)
 Evaluating proposed model changes
 Providing model interpretation for customers
 Collaboration among forecasters
– Forecasts (multiple forecast offices)
– Analyses (seamless surface analysis)
13
NCEP Vision: First Choice – First Alert – Preferred Partner
NWS Unified Surface Analysis
First operational issuance – 12 UTC June 14, 2004
HPC, OPC, TPC, & HFO
14
NCEP Vision: First Choice – First Alert – Preferred Partner
Concluding remarks -The numerical models & forecasters:
a love/hate relationship?
• Numerical forecasts initially viewed as threat to job security
& satisfaction
• Inner workings of numerical models still appear arcane &
difficult to fathom
• When models change, forecasters must learn the new model biases,
strengths, & weaknesses
• Improving numerical guidance gives forecasters less room to make
improvements
• Yet forecasters want to improve
the quality of their products &
services, so they demand more
accurate numerical tools
• Result-- Forecasters, numerical
guidance, and meteorological
workstations are inseparable,
tightly interwoven in the
forecast process
15
NCEP Vision: First Choice – First Alert – Preferred Partner