CHAPTER 13 BENJAMIN ET AL. 13.1 Chapter 13 100 Years of Progress in Forecasting and NWP Applications STANLEY G. BENJAMIN AND JOHN M. BROWN NOAA/Office of Oceanic and Atmospheric Research/Earth System Research Laboratory Global Systems Division, Boulder, Colorado a GILBERT BRUNET Environment and Climate Change Canada, Montreal, Quebec, Canada PETER LYNCH University College Dublin, Dublin, Ireland KAZUO SAITO Atmosphere and Ocean Research Institute, University of Tokyo, Tokyo, Japan b THOMAS W. SCHLATTER NOAA/Office of Oceanic and Atmospheric Research, Boulder, Colorado ABSTRACT Over the past 100 years, the collaborative effort of the international science community, including gov- ernment weather services and the media, along with the associated proliferation of environmental observa- tions, improved scientific understanding, and growth of technology, has radically transformed weather forecasting into an effective global and regional environmental prediction capability. This chapter traces the evolution of forecasting, starting in 1919 [when the American Meteorological Society (AMS) was founded], over four eras separated by breakpoints at 1939, 1956, and 1985. The current state of forecasting could not have been achieved without essential collaboration within and among countries in pursuing the common weather and Earth-system prediction challenge. AMS itself has had a strong role in enabling this international collaboration. 1. Introduction in our ability to observe the atmosphere, by application of rigorous physical principles to understanding atmo- Weather forecasting has evolved over the past century spheric phenomena, and by the advent and subsequent from being an empirical, analog-based process with little enormous increase in digital computing capability. Daily skill to an increasingly automated high-tech enterprise decisions, with outcomes from inconsequential to far- demonstrating tremendous prediction accuracy. This reaching in magnitude made by groups and individuals, transformation has been enabled by spectacular advances are based on the forecast community’s assessment of fu- ture environmental conditions—forecasting, and espe- a Current affiliation: Bureau of Meteorology, Melbourne, Vic- cially, weather forecasting. Vilhelm Bjerknes (Bjerknes toria, Australia. 1911) referred to forecasting as the ultimate problem in b Retired. meteorology. In this chapter, we trace the progress of weather fore- Corresponding author: Stan Benjamin, [email protected] casting and scientific questions leading to that progress DOI: 10.1175/AMSMONOGRAPHS-D-18-0020.1 Ó 2019 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses). Unauthenticated | Downloaded 10/08/21 04:54 AM UTC 13.2 METEOROLOGICAL MONOGRAPHS VOLUME 59 TABLE 13-1. Overview—100 years of progress in forecasting within four historical eras and for eight components of forecasting. Community of forecast Observations used for Science understanding providers (government and State of forecasting forecasting influencing forecasting specialized forecasters) Era 1: 1919–39 Empirical; little skill; based Surface obs primarily; Bergen 3D airmass frontal Government agencies were on surface weather maps virtually no real-time structure for extratopics dominant in the early and extrapolation of observations above the but only small impact on forecast-provider patterns surface except for a few forecasting community aircraft soundings Era 2: 1939–56 Forecasting for military Rawinsondes enabled by 3D structure of baroclinic Government–military central in WWII; upper- radio transmission; radar waves and jet streams cooperation; university level charts became developed but not yet revealed by increased departments formed; widely available to available widely upper-air obs; QG theory private sector emerges; understand patterns and baroclinic instability international community of national agencies Era 3: 1956–85 After 1958–60, NWP used Introduction of weather Convective-storm and International meteorology for upper-level changes satellites—images for mesoscale convective community grows but surface conditions short-term forecasting system dynamics; (GARP; WMO) for obs and QPF were inferred; and retrievals for NWP; importance of latent and forecasting; national severe weather radar network in United heating and other physics weather services forecasting added States for NWP modernize Era 4: 1985–2018 Steady increase in Increased satellite coverage, Oceanic cyclogenesis; more Role increases with dependency on NWP especially for microwave complete understanding stronger overall during this era with andGNSSandfor of small-scale processes environmental gradual transformation of geostationary; DA of enabling improved awareness; forecasters human role from radiances; increased radar subgrid-scale physical- become more modifying NWP into data in most countries, process communicators as NWP communication with including Doppler parameterizations (cloud; matures; private sector of users velocity; automated turbulence; fluxes from forecasters strengthens commercial aircraft data ground) with public and academic added, especially in 1990s toward a ‘‘global weather and 2010s enterprise’’ Next 30 years Yet more automation of Integrated, cost-effective Increased understanding of Maturing of GWE with forecasting process, obs network will meet weather systems in terms stronger roles of public, allowing more forecaster demands of seamless of local phenomena and private, and academic focus on communication weather/climate multiscale interaction with components and to decision-makers, forecasting; NEWP DA other systems (e.g., intercoordination; WMO especially in critical high- will become continuous atmosphere–ocean– will continue impact weather events, and use increasing waves), dynamic processes coordinating, and model evaluation traditional and new (e.g., moist and dry air in- disseminating, and sources of atmosphere– teractions), and physical implementing NEWP ocean–land–cryosphere– processes (e.g., chemistry innovations developed by biosphere obs interaction between aero- national services to sol and cloud microphysics) benefit all nations over the last 100 years. This progress is broken down here in understanding the atmosphere–Earth system (e.g., into four 20–30-yr periods, in each of which, the science Randall et al. 2019). Repeated application of the sci- and practice of forecasting underwent major shifts. entific method—asking questions, constructing new This chapter on forecasting complements scientific hypotheses, and then conducting experiments and developments described in other chapters of this collecting observations to test them—is behind the monograph and distills from them. The science of fore- development of weather forecasting and all of the casting has followed close on the heels of overall progress science topics of this monograph. in atmospheric science (understanding and numerical In each era, we identify, where appropriate, obser- representation of physical processes and phenomena vations used for forecasting and the process of ana- described in other chapters) but has often, in turn, lyzing those observations into a coherent picture accelerated research in these related areas, often fol- (a weather map), growth in the scientific under- lowing major forecasting failures. Forecasting, in general, standing that influenced the practice of forecasting, and numerical prediction models have aided tremendously the community of weather forecast providers from Unauthenticated | Downloaded 10/08/21 04:54 AM UTC CHAPTER 13 BENJAMIN ET AL. 13.3 TABLE 13-1. (Extended) Technology advances Media; communication; leading to changes in comprehension of Forecasting applications Quantitative forecasting (NWP) forecasting/science forecasting by the public Public, agriculture, and None yet but groundwork being laid Teletype relay for obs; Primarily newspapers; radio marine safety; aviation (Richardson; Rossby; Bjerknes) rawinsondes developed emerges; skepticism from enters as a major driver using radio relay the public but widespread use enabled by radio Aviation—military and NWP development begins (JNWPU; Invention of digital Radio; television gains civilian; public safety Sweden); not yet used for forecasting computer enables initial prominence NWP development Watch and warning for Rapid advance in NWP from equivalent Steady increase in Television is primary severe weather/flash barotropic to PE models with limited computing; design of first medium; specialized floods; improved physics; initial DA; first global models interactive display cable networks started awareness of aviation systems for weather data hazards from severe local storms Weather dependence Global models, especially spectral, with More powerful computing Increasing accuracy for recognized for public advanced DA, including direct DA of for NWP and interactive weather hazards safety and in all economic satellite radiances; regional models display systems and recognized for longer sectors for decision- used widely for short range; interactive production of duration and at smaller making (transport, severe nonhydrostatic models for severe/local forecasts; Internet used scales; cable, personal weather, energy, etc.); weather; transition into Earth-system for scientific computers, Internet, and climate and subseasonal- prediction; probabilistic and ensemble collaboration cellular-phone to-seasonal-prediction prediction availability