SCIENCE13 - Weather Forecasting

I’ve written about clouds, weather, and the wind.  I decided that it was about time to write about weather forecasting.

 

 

After a short introduction, I’ll cover the early history of weather forecasting, the transition to modern methods, upper-air balloon observations, the beginning of numerical weather prediction, weather forecasting organizations, today’s tools and techniques for weather forecasting, computer models, weather broadcasts to the public, applications and benefits of weather forecasting, and finally, a snapshot of the future of weather forecasting.

My principal sources include “Weather Forecasting,” Wikipedia.com; “Weather Forecasting,” britannica.com; “Weather forecasting Through the Ages,” earthobservatory.nasa.gov; “6 tools our meteorologists use to forecast the weather,” noaa.gov; “National Weather Service History,” zippia.com; “How AI is Improving Weather Forecasting,” aiplusinfo.com; plus, numerous other online sources.

Introduction

Weather forecasting is the application of science and technology to predict the weather for a given location and time.  In addition to predictions of atmospheric phenomena themselves, weather forecasting includes predictions of changes on the Earth’s surface caused by atmospheric conditions - e.g., snow and ice cover, storm tides, and floods.  People have attempted to predict the weather informally for millennia and formally since the 19^th century.

Weather forecasts are made by collecting quantitative data about the current state of the atmosphere, land, and ocean, and using meteorology (the science of atmospheric physics) to project how the atmosphere will change at a given place.

Once calculated manually, based mainly upon changes in barometric pressure, current weather forecasting now relies on computer-based models that take many atmospheric factors into account.  Human input is still required to pick the best possible model on which to base the forecast.

The inaccuracy of forecasting is due to the chaotic nature of the atmosphere; the massive computational power required to solve the equations that describe the atmosphere, the land, and the ocean; the error involved in measuring the initial conditions; and an incomplete understanding of atmospheric and related processes.  Hence, forecasts become less accurate as the difference between current time and the time for which the forecast is being made (the range of the forecast) increases.

Early History

The art of weather forecasting began with early civilizations using recurring astronomical and meteorological events to help them monitor seasonal changes in the weather.  Around 650 B.C., the Babylonians tried to predict short-term weather changes based on the appearance of clouds and optical phenomena such as haloes (a circle of white or colored light around the Sun).  By 300 B.C., Chinese astronomers had developed a calendar that divided the year into 24 festivals, each festival associated with a different type of weather.

Around 340 B.C., the Greek philosopher Aristotle wrote Meteorologica, a philosophical treatise that included theories about the formation of rain, clouds, hail, wind, thunder, lightning, and hurricanes.  Aristotle made some remarkably astute observations concerning the weather (along with some significant errors) and his text was considered by many to be the authority on weather theory for almost 2000 years. 

Throughout the centuries, attempts were made to produce forecasts based on weather lore and personal observations.  However, by the end of the Renaissance (17^th century), it had become increasingly evident that the speculations of the natural philosophers were inadequate and that greater knowledge was necessary to further our understanding of the atmosphere. 

Towards Modern Methods

The scientific study of meteorology did not develop until instruments became available to measure the properties of the atmosphere, such as moisture, temperature, and pressure.  The first known design in western civilization for a hygrometer, an instrument to measure the humidity of air, was described by German Nicholas Cusa in the mid-15^th century.  Italian Galileo Galilei invented an early thermometer in 1592 or shortly thereafter; and Italian Evangelista Torricelli invented the mercury barometer for measuring atmospheric pressure in 1643.

Italian scientist Evangelista Torricelli invented the mercury barometer for measuring atmospheric pressure.

 

A succession of notable achievements by chemists and physicists of the 17^th and 18^th centuries contributed significantly to meteorological research.  The formulation of the laws of gas pressure, temperature, and density by Robert Boyle and Jacques-Alexandre-César Charles; the development of calculus by Isaac Newton and Gottfried Wilhelm Leibniz; the development of the law of partial pressures of mixed gases by John Dalton; and the formulation of the doctrine of latent heat (i.e., heat release by condensation or freezing) by Joseph Black are just a few of the major scientific breakthroughs of the period that made it possible to measure and better understand theretofore unknown aspects of the atmosphere and its behavior.  During the 19^th century, all of these brilliant ideas began to produce results in terms of useful weather forecasts.

The invention of the telegraph in 1837 by American Samuel F.B. Morse and the ensuing emergence of telegraph networks allowed the rapid routine transmission of weather observations to and from observers and compilers of the data.  By 1849, Joseph Henry of the Smithsonian Institution in Washington, D.C. was plotting daily weather maps based on telegraphic reports, and in 1869 Cleveland Abbe at the Cincinnati Observatory began to provide regular weather forecasts using data received telegraphically.  Surface wind patterns and storm systems could be identified and studied. 

Weather-observing stations began appearing all across the globe, spawning the birth of synoptic weather forecasting, the compilation and analysis of many observations taken simultaneously over a wide area.

It was not long before national meteorological services were established.  The first national weather service in the United States was founded in 1870, with responsibility assigned to the U.S. Army Signal Corps.  The original purpose of the service was to provide storm warnings for the Atlantic and Gulf coasts, and for the Great Lakes.  Within the next few decades, national meteorological services were established in many countries across the globe. The importance of international cooperation in weather prognostication was recognized by the directors of such national services.  By 1880 they had formed the International Meteorological Organization (IMO).

The proliferation of weather-station networks linked by telegraphy made synoptic forecasting a reality by the close of the 19^th century.  Yet, the daily weather forecasts generated left much to be desired.  Many errors occurred because predictions were largely based on the experience that each individual forecaster had accumulated over several years of practice, vaguely formulated rules of thumb (e.g., of how pressure systems move from one region to another), and associations that were poorly understood, if at all.

Upper-Air Observations from Balloons

An important aspect of weather prediction is to calculate the atmospheric pressure pattern - the positions of the highs and lows, and their changes.  Modern research has shown that sea-level pressure patterns respond to the motions of the upper-atmospheric winds, with their narrow, fast-moving jet streams and waves that propagate through the air and pass air through themselves.

Frequent surprises and errors in estimating surface atmospheric pressure patterns caused 19^th-century forecasters to seek information about the upper atmosphere for possible explanations.  The British meteorologist James Glaisher made a series of ascents by balloon during the 1860s, reaching an unprecedented height of five miles.  At about this time, investigators on the Continent began using unmanned balloons to carry recording barographs, thermographs, and hygrographs to high altitudes.  During the late 1890s, meteorologists in both the United States and Europe used kites equipped with instruments to probe the atmosphere up to altitudes of about two miles. 

Notwithstanding these efforts, knowledge about the upper atmosphere remained very limited at the turn of the century.  The situation was aggravated by the confusion created by observations from weather stations located on mountains or hilltops.  Such observations often did not show what was expected, partly because so little was known about the upper atmosphere, and partly because the mountains themselves affect measurements, producing results that are not representative of what would be found in the free atmosphere at the same altitude.

Once again technology provided the means with which to test the new scientific ideas and stimulate yet newer ones.  During the late 1920s and 30s, several groups of investigators began using small radio transmitters with balloon-borne instruments, eliminating the need to recover the instruments and speeding up access to the upper-air data.  These radiosondes, as they came to be called, gave rise to the upper-air observation networks that still exist today. 

U.S. Bureau of Standards personnel launching a radiosonde near Washington, DC in 1936.

 

Numerical Weather Forecasting

The idea of numerical weather forecasting - predicting the weather by solving mathematical equations - was formulated in 1904 by Norwegian Vilhelm Bjerknes, and developed by British mathematician Lewis Fry Richardson.  Despite the advances made by Richardson, it took him, working alone, several months to produce a wildly inaccurate six-hour forecast for an area near Munich, Germany.  Richardson’s work highlighted the obvious fact that a large number of calculations had to be made very rapidly in order to produce a timely forecast.

 

British mathematician Lewis Fry Richardson pioneered modern numerical weather forecasting.

In the late 1940s, using one of the earliest modern computers, significant progress toward more practical numerical weather forecasts was made by a team of meteorologists and mathematicians at the Institute for Advanced Study in Princeton, New Jersey.  Hungarian-American mathematician John von Neumann directed the construction of the computer and put together a team of scientists led by American Jule Charney to apply the computer to weather forecasting.  Charney determined that the impracticality of Richardson’s methods could be overcome by using the new computers and simplified calculations that focused on the phenomena of most importance to predicting the evolution of continent-scale weather systems.  In April 1950, Charney’s group made a series of successful 24-hour forecasts over North America, and by the mid-1950s, numerical forecasts, spurred by the development of programmable electronic computers, were being made on a regular basis.

National Weather Forecasting Organizations

Several countries founded government agencies to provide forecasts and watches/warnings/advisories to the public to protect life and property and maintain commercial interests.  Besides the U.S., the European Union is a major source of weather data, but the British, French, German, Japanese, Canadians, and Chinese all have their own national weather services too.

In the United States as mentioned earlier, the National Weather Service (NWS) was founded in 1870 within the U.S. Army Signal Service.  In 1891, the NWS was transferred to the Department of Agriculture and renamed the Weather Bureau.  Finally, in 1940, the Weather Bureau was transferred to the Department of Commerce where it remains today.  In 1967, the Weather Bureau was renamed the National Weather Service (NWS) and became a component of the Commerce Department’s newly-created National Oceanic and Atmospheric Administration (NOAA).

Modern Tools and Techniques    

Meteorologists at NOAA’s National Weather Service have long monitored the conditions of the atmosphere that impact the weather, but over time, the equipment they use has changed.  As technology advanced, scientists began to use more efficient equipment to collect and use additional data. These technological advances enable meteorologists to make better predictions faster than ever before. 

Modern tools for weather forecasting.

No.	Tool	Features
1	Doppler Radar	Doppler Radar is the meteorologist’s window into observing severe storms.  With 159 radar towers across the United States, NOAA’s National Weather Service has comprehensive coverage of the continental U.S. and partial coverage of Alaska, Hawaii, Puerto Rico, and Guam.  Doppler radar detects all types of precipitation, the rotation of thunderstorm clouds, airborne tornado debris, and wind strength and direction.
2	Satellite Data	Weather Satellites monitor Earth from space, collecting observational data scientists analyze.  NOAA operates three types of weather satellites.  Polar orbiting satellites circle the Earth close to the surface, taking six or seven detailed images a day.  Geostationary satellites stay over the same location on Earth, high above the surface, taking images of the entire Earth as frequently as every 30 seconds.  Deep space satellites face the sun to monitor powerful solar storms and space weather.  NOAA also uses data from satellites operated by other agencies and countries.
3	Radiosondes	Radiosondes are the primary source of upper-air data.  At least twice per day, radiosondes are tied to weather balloons and are launched in 92 locations across the United States.  In its two-hour trip, the radiosonde floats to the upper stratosphere where it collects and sends back data every second about air pressure, temperature, relative humidity, wind speed and wind direction.  During severe weather, weather balloons are launched more frequently to collect additional data about the storm environment.
4	Automated Surface-Observing Systems (ASOS)	ASOS - a joint effort of the NWS, the FAA, and DOD - constantly monitor weather conditions on the Earth’s surface.  More than 900 stations across the U.S. report data about sky conditions, surface visibility, precipitation, temperature and wind up to 12 times an hour.  In addition, early 10,000 volunteer NWS-cooperative observers collect and provide temperature, snowfall, and rainfall data.  The observational data that ASOS and volunteers collect are essential for improving forecasts and warnings.
5	Supercomputers	NOAA’s Weather and Climate Operational Supercomputer System (WCOSS) is the backbone of modern forecasting.  With 5.78 petaflop computing capacity, it can process quadrillions of calculations per second.  The supercomputers are almost 6 million times more powerful than the average desktop computer.  Observational data collected by doppler radar, radiosondes, weather satellites, buoys, and other instruments are fed into computerized NWS numerical forecast models.
6	Advanced Weather information Processing System (AWIPS)	AWIPs is a computer processing system that combines data from all the previous tools into a graphical interface that forecasters use to analyze data and prepare and issue forecasts, watches, and warnings.  This system uses NOAA supercomputers to process data from doppler radar, radiosondes, weather satellites, ASOS, and other sources using models and forecast guidance products.  After meteorologists prepare the forecasts, AWIPS generates weather graphics and hazardous weather watches and warnings.

 

Computer Models

In the past, the human forecaster was responsible for generating the entire weather forecast based upon available observations. Today, human input is generally confined to choosing a computer model, or group of computer models, based on various parameters, such as model performance and known biases.

Essentially, a model is a computer program that produces meteorological information for future times at given locations and altitudes.  Weather models use systems of differential equations based on the laws of physics, to model fluid motion, thermodynamics, radiative transfer, and chemistry; and use a coordinate system which divides the planet into a 3D grid.  Winds, heat transfer, solar radiation, relative humidity, phase changes of water, and surface hydrology are calculated within each grid cell, and the interactions with neighboring cells are used to calculate atmospheric properties in the future.

 Different models use different solution methods.  Using a consensus of forecast models can help reduce forecast error.  The raw computer model output is often modified before being presented as the forecast. This can be in the form of statistical techniques to remove known biases in the model, or of adjustment to take into account consensus among other numerical weather forecasts.  However, regardless how small the average error becomes with any individual system, large errors are still possible on any given model run.

Schematic of scope of weather forecasting computer models.

 

Humans are required to interpret the model data into weather forecasts that are understandable.  Humans can also use knowledge of local effects that may be too small in size to be resolved by the model(s) to add information to the forecast.  While increasing accuracy of forecast models implies that humans may no longer be needed in the forecast process at some point in the future, there is currently still a need for human intervention.  (See Future Improvements, below.)

Note:  Weather data is provided free by the U.S. government through NOAA, making it relatively easy for anyone to develop a weather forecasting service.  But the forecast also depends on the experience of the meteorologist and how he or she interprets the models.  There are models that are better at handling certain weather events (e.g., hurricanes or snowstorms), and models that are better designed for long-term or short-term forecasting.  It's the meteorologist's job to know the reputation of each model, and adjust and improve the forecast based on this knowledge.  Ultimately, there's variation that comes from the different computer models, and then organizations have their own formulas and meteorologists that adjust those forecasts further.  This is why weather forecasts from different weather services don’t exactly agree.

Communicating Forecasts to the Public

Traditionally, newspaper, television, and radio have been the primary outlets for presenting weather forecast information to the public.  Increasingly, the internet is being used due to the vast amount of specific information that can be found.  In all cases, these outlets update their forecasts on a regular basis.

The first ever daily weather forecasts were published in Britain’s The Times on August 1, 1861, and the first weather maps were produced later in the same year.  In 1911, the Met Office, the national weather service of Great Britain, began issuing the first marine weather forecasts via radio transmission. These included gale and storm warnings for areas around Great Britain.  In the United States, the first public radio forecasts were made in 1925 by Edward B. "E.B." Rideout, on radio station WEEI, the Edison Electric Illuminating station in Boston.  Rideout came from the U.S. Weather Bureau.

The world's first televised weather forecasts, including the use of weather maps, were experimentally broadcast by the BBC in November 1936.  This was brought into practice in 1949, after World War II.  George Cowling gave the first weather forecast while being televised in front of the map in 1954.  In America, experimental television forecasts were made by James C. Fidler in Cincinnati in the 1940s, on the DuMont Television Network.  In the late 1970s and early 80s, John Coleman, the first weatherman on ABC-TV's Good Morning America, pioneered the use of on-screen weather satellite information and computer graphics for television forecasts.  Coleman was a co-founder of The Weather Channel (TWC) in 1982.   TWC is now a 24-hour cable network.  Some weather channels have started broadcasting on live broadcasting programs such as YouTube to reach more viewers.

Al Roker’s weather forecast on the morning TV show TODAY: Dec. 16, 2021.

 

Note:  I “Googled” the weather in Tucson, Arizona this morning and found 13 online sites, not counting newspapers and TV/radio stations, that provided detailed weather forecasts. 

Applications/Benefits

The importance of accurate weather forecasts cannot be over emphasized as the needs for them are present in virtually every aspect of life.  Weather forecasts can be applied in the following areas:

Applications of Weather Forecasting.

No.	Application Area	Benefits
1	Severe Weather Alerts and Advisories	A major part of modern weather forecasting that the NWS issues in the case that severe or hazardous weather is expected.  This is done to protect life and property.  These include   severe thunderstorm and tornado warnings, severe thunderstorm and tornado watches, and hurricane warnings.  Other forms of these advisories include winter weather, high wind, flood, and fog.  Severe weather advisories and alerts are broadcast through the media, including radio, using emergency systems as the Emergency Alert System, which break into regular programming.
2	Agriculture	Farmers rely on weather forecasts to decide what work to do on any particular day; for example, drying hay is only feasible in dry weather.  Prolonged periods of dryness can ruin cotton, wheat, and corn crops.  Frosts and freezes play havoc with crops both during the spring and fall; for example, peach trees in full bloom can have their potential peach crop decimated by a spring freeze.  Orange groves can suffer significant damage during frosts and freezes, regardless of their timing.  Also, international trading of foodstuffs such as wheat, corn, beans, sugar, cocoa, and coffee can be severely affected by weather news.
3	Forestry	Forecasting of wind, precipitation, and humidity is essential for preventing and controlling wildfires. Conditions for the development of harmful insects can also be predicted by forecasting the weather.
4	Aviation	Accurate weather forecasting for aviation is essential.  Fog or exceptionally low ceilings can prevent many aircraft from landing and taking off.  Turbulence and icing are also significant in-flight hazards.  Thunderstorms are a problem for all aircraft because of severe turbulence due to their updrafts and   outflow boundaries, icing due to the heavy precipitation, as well as large hail, strong winds, and lightning, all of which can cause severe damage to an aircraft in flight. Volcanic ash is also a significant problem for aviation, as aircraft can lose engine power within ash clouds.  On a day-to-day basis airliners are routed to take advantage of the jet stream tailwind to improve fuel efficiency.  Aircrews are briefed prior to takeoff and the conditions to expect enroute and at their destination.  Additionally, airports often change which runway is being used to take advantage of a headwind.  This reduces the distance required for takeoff, and eliminates potential  crosswinds.
5	Marine	Use of waterways can be limited significantly by wind direction and speed, wave periodicity and heights, tides, and precipitation. These factors can each influence the safety of marine transit. Many oceangoing shipping vessels as well as military ships use optimum ship routing forecasts to plan their routes in order to minimize lost time, potential damage, and fuel consumption in heavy seas.
6	Military	Accurate weather forecasting is critical in performing military operations such as Operation Overlord, the invasion of the European mainland at Normandy by Allied forces during World War II.
7	Commercial	Electricity and gas companies rely on weather forecasts to determine demand for heating or cooling. Ski-resort operators may need predictions of nighttime relative humidity on the slopes within 5 to 10 percent in order to schedule snow making. Marketing organizations and stores hire weather-forecasting consultants to help with the timing of sales and promotions of products ranging from snow tires and roofing materials to summer clothes and resort vacations.  Supermarket chains may change the stocks on their shelves in anticipation of different consumer spending habits in different weather conditions.
8	Private	Weather forecasts are of prime importance for individuals planning travel, considering local recreation, scheduling home improvements, landscaping, gardening, and many more activities.

 

Future Improvements in Weather Forecasting

Only 50 years ago, weather forecasting was an art, derived from the inspired interpretation of data from a loose array of land-based observing stations, balloons, and aircraft. Since then, it has evolved substantially, based on an array of satellite and other observations and sophisticated computer models simulating the atmosphere and sometimes additional elements of the Earth’s climate system. 

So far, the accuracy of short-range forecasting has been of immense help and advantage to the world at large, but the accuracy of long-range forecasting has been minimal.  There a lot of volatile variables within the atmosphere, such as turbulent air, high-pressure systems, and so on, that have to be forecasted for different times within the next hour, within the next day, and within the next week.

Future technology improvements should further weather forecasting advances, enabling more accurate predictions over longer periods.

There is no doubt that artificial intelligence (AI), combined with high-performance computing, will have a great impact on the quality of weather forecasting.  In recent years, weather forecasters have been relying more and more on these tools to analyze massive amounts of data and determine patterns that could indicate severe weather.  AI advances promise weather prediction advances which can accurately predict heavy rain, inches of rain, rain accumulations, tracks of hurricanes, and other extreme weather conditions.  Predictive technologies combined with powerful algorithms will enhance weather forecasts significantly.

 

Improving future short-term and long-term weather forecasts will depend on more accurate sensor data and observations, improved understanding of atmospheric physics, and continued improvement of computer modeling fidelity and speed – all assisted by the application of artificial intelligence tools.

For weather prediction to keep improving, there needs to be a steady stream of monetary investment and human effort. Data collection needs to continue apace from the ground, sky, and space.  AI needs to be crafted and applied within earth sciences, particularly to learn more about intricate physical processes like cloud-aerosol interactions that still aren’t well understood. Governments also need to pay for supercomputing infrastructure to run increasingly advanced weather prediction models.

Weather forecasting is a complex and challenging science that depends on the efficient interplay of weather observation, data analysis by meteorologists and computers, and rapid communication systems. Meteorologists have achieved a very respectable level of skill for shortrange weather forecasting.  Further improvement is expected with denser surface and upper-air observational networks, more precise numerical models of the atmosphere, and larger and faster computers.  However, continued international cooperation is essential, for the atmosphere is a continuous fluid that knows no political boundaries.