# Presentation: 079973

## 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 50*__*th*__* Anniversary of *__*Operational Numerical Weather Prediction*_June 16, 2004

*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**

## HPC QPF verification1-inch threat score

## HPC QPF verification vs. the modelsDay 1, 1 inch

## HPC medium-range Tmax verification% reduction in Mean Absolute Error over MOS(by year) (adjusted stations only)

## 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**

## 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**

## Estimated HPC meteorological technician & reproduction-equipment technician staffing by year

**	****	**_**met**_**	**_**repro**_**	**
_**year**_**	**_**techs**_**	**_**techs**_**	**_**total**_**	**
**1970****	****97****	****15****	****112****	**
**1975****	****82****	****14****	**** **** 96****   ****	**
**1980****	****47****	****14****	****  ****61****	**
**1986****	****28****	****11****	**** **** 39****	**
**1990****	****21****	****  8****	****  ****29 **** ****	**
**	****	****	****	****   ****	**
**1994****	****12****	****  7****	****  ****19****	**
**1995****	****  9****	****  6****	****  ****15**** ****	**
**1997****	****  4****	****  0****	****  ****  4****	**
**	****	****	****	****   ****	**
**	****	****	****	****   ****	**
**2002****	****  3            0           **** 3****	**

## “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**

## Providing oversight (continued)

## “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**

## Providing model interpretation for customers (continued)

## “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)**

## NWS Unified Surface AnalysisFirst operational issuance – 12 UTC June 14, 2004HPC, OPC, TPC, & HFO

## 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**