Map of Contour line - The Full Wiki The Full Wiki Wikipedia article: Map showing all locations mentioned on Wikipedia article: A contour line (also level set , isopleth, isoline, isogram or isarithm) of a function of two variables is a curve along which the function has a constant value. In cartography , a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level . A contour map is a map illustrated with contour lines, for example a topographic map , which thus shows valleys and hills, and the steepness of slopes. The contour interval of a contour map is the difference in elevation between successive contour lines. More generally, a contour line for a function of two variables is a curve connecting points where the function has a same particular value. The gradient of the function is always perpendicular to the contour lines. When the lines are close together the length of the gradient is large: the variation is steep. If adjacent contour lines are of the same line width, the direction of the gradient cannot be determined from the contour lines alone.

However if contour lines rotate through three or more widths, or if the lines are numerically labelled, then the direction of the gradient can also be determined from the contour lines. Contour lines are curved or straight lines on a map describing the intersection of a real or hypothetical surface with one or more horizontal planes. The configuration of these contours allows map readers to infer relative gradient of a parameter and estimate that parameter at specific places. Contour lines may be either traced on a visible three-dimensional model of the surface , as when a photogrammetrist viewing a stereo-model plots elevation contours, or interpolated from estimated surface elevations , as when a computer program threads contours through a network of observation points of area centroids. In the latter case, the method of interpolation affects the reliability of individual isolines and their portrayal of slope , pits and peaks. Types of contour lines Contour lines are often given specific names beginning "iso-" (from Greek ισος (isos), meaning 'equal') according to the nature of the variable being mapped, although in many usages the word "contour line" is most commonly used. Specific names are most common in meteorology, where multiple maps with different variables may be viewed simultaneously.

In general, an isogon is a line along which an angle is held constant. "Iso-" can be replaced with "isallo-" to specify a contour line connecting points where a variable changes at the same rate during a given time period(also termed as isobar). Meteorology Isohyetal map Meteorological contour lines are based on generalization from point data received from weather stations . Weather stations are seldom exactly positioned at a contour line (when they are, this indicates a measurement precisely equal to the value of the contour). Instead, lines are drawn to best approximate the locations of exact values, based on the scattered information points available. Meteorological contour maps may present collected data such as actual air pressure at a given time, or generalized data such as average pressure over a period of time, or forecast data such as predicted air pressure at some point in the future Thermodynamic diagrams use multiple overlapping contour sets (including isobars and isotherms) to present a picture the major thermodynamic factors in a weather system.

Barometric pressure An isobar (from βαρος or baros, meaning 'weight') is a line of equal or constant pressure on a graph, plot, or map; an isopleth or contour line of pressure.More accurately, isobars are lines drawn on a map joining places of equal average atmospheric pressure reduced to sea level for a specified period of time. In meteorology , the barometric pressures shown are reduced to sea level , not the surface pressures at the map locations. The distribution of isobars is closely related to the magnitude and direction of the wind field, and can be used to predict future weather patterns.Isobars are commonly used in television news weather reporting, though more commonly in Europe than in the United States. An isostere is a line of constant atmospheric density. An isoheight or isohypse is a line of constant geopotential height on a constant pressure surface chart. Temperature and related subjects An isotherm (from θερμη or thermē, meaning 'heat') is a line that connects points on a map that have the same temperature . Therefore, all points through which an isotherm passes have the same temperatures at the time indicated.

Generally, isotherms representing 5°C or 10°F temperature differences are used, but any interval may be chosen. An isogeotherm is a line of equal mean annual temperature. An isocheim is a line of equal mean winter temperature, and an isothere is a line of equal mean summer temperature. An isohel (from έλιος or helios, meaning 'sun') is a line of equal or constant solar radiation . Precipitation and air moisture An isohyet or isohyetal line (from ύετος or huetos, meaning 'rain') is a line joining points of equal precipitation on a map . A map with isohyets is called an isohyetal map. An isohume is a line of constant relative humidity , while a isodrosotherm (from δροσος or drosos, meaning 'dew', and θερμη or therme, meaning 'heat') is a line of equal or constant dew point . An isoneph is a line indicating equal cloud cover.

An isochalaz is a line of constant frequency of hail storms, and an isobront is a line drawn through geographical points at which a given phase of thunderstorm activity occurred simultaneously. Snow cover is frequently shown as a contour-line map. Wind An isotach (from ταχ or tach, meaning 'speed') is a line of constant wind speed.In general, an isogon is a line along which an angle is held constant. In meteorology, the term refers to a line of constant wind direction. Freeze and thaw An isopectic line denotes equal dates of ice formation each winter, and an isotac denotes equal dates of thawing. Physical geography and oceanography Elevation and depth Contours are one of several common methods used to denote elevation or altitude and depth on maps . From these contours, a sense of the general terrain can be determined. They are used at a variety of scales, from large-scale engineering drawings and architectural plans, through topographic maps up to continental-scale maps. "Contour line" is the most common usage in cartography , but isobath for underwater depths on bathymetric maps and isohypse for elevations are also used.

The process of drawing isohypse contour lines on a map is called isopletion. In cartography, a contour interval is any space between contour lines, representing a difference in elevation between the lines. When calculated as a ratio against the map scale, a sense of the hilliness of the terrain can be derived. Magnetism In general, an isogon is a line along which an angle is held constant. In geomagnetism , the term refers to a line of constant magnetic declination (variance of magnetic north from geographic north). Isogonic lines are lines connecting those parts where the declination of the Earth's magnetic field is the same in amount. They are similar to isoclinic lines , which are lines connecting points of equal magnetic inclination. The line drawn through the points of zero magnetic declination is called the agonic line . Oceanography Besides ocean depth, oceanographers use contour to describe diffuse variable phenomena much as meteorologists do with atmospheric phenomena. In particular, isobathytherms are lines showing depths of water with equal temperature, isohalines show lines of equal ocean salinity, and Isopycnals are surfaces of equal water density.

Geology Various geological data are rendered as contour maps in structural geology , sedimentology , stratigraphy and economic geology . Contour maps are used to show the below ground surface of geologic strata , fault surfaces (especially low angle thrust faults ) and unconformities . Isopach maps use isopachs (lines of equal thickness) to illustrate variations in thickness of geologic units. Environmental science In discussing pollution, density maps can be very useful in indicating sources and areas of greatest contamination. Contour maps are especially useful for diffuse forms or scales of pollution. Acid precipitation is indicated on maps with isoplats. Some of the most widespread applications of environmental science contour maps involve mapping of environmental noise , air pollution , soil contamination , thermal pollution and groundwater contamination. Social sciences In economics , contour lines can be used to describe features which vary quantitatively over space. An isochrone shows lines of equivalent drive time or travel time to a given location. An isotim shows equivalent transport costs from the source of a raw material, and an isodopane shows equivalent cost of travel time. Indifference curves are used to show bundles of goods to which a person would assign equal utility.

In political science an analogous method is used in understanding coalitions (for example the diagram in Laver and Shepsle's work) In population dynamics , isocline refers to the set of population sizes at which the rate of change, or partial derivative, for one population in a pair of interacting populations is zero. Isolines can also be used to delineate qualitative differences. An isogloss , for example, is used in mapping the geographic spread of linguistic features. Contour lines are also used in non-geographic charts in economics. An isoquant is a line of equal production quantity, and an isocost shows equal production costs. Thermodynamics, engineering, and other sciences Various types of graphs in thermodynamics , engineering, and other sciences use isobars (for showing constant pressure), isotherms (for constant temperature), isochors (for constant specific volume), or other types of iso-lines (or curves), even though these graphs are usually not related to maps. Such iso-lines are useful for representing more than two dimensions (or quantities) on two-dimensional graphs. Common examples in thermodynamics are some types of phase diagrams . An Isocline is generically a line of equal slope.

Isoclines are used to solve ordinary differential equations . In interpreting radar images, an isodop is a line of equal Doppler velocity, and an isoecho is a line of equal radar reflectivity. Other phenomena Contour line - GIS Wiki | The GIS Encyclopedia Contour line Jump to: navigation , search This article is about lines of equal value in maps and diagrams. For more meanings of the word "contour", see Contour . "Isopleth" and "Contour map" and "Contour interval" redirect here. A topographic map with relief shown by an elevation contour map A mathematical contour plot of the function f(x)=sin(x2+y2)cos(x)sin(y). Along the x-axis at -π/2 and π/2 it is constant zero, as it is on the y-axis at all integer multiples of π—hence the lines; the origin -centered circles are x2+y2 = π, x2+y2 = 2π ... A contour line (also level set, isopleth, isoline, isogram or isarithm) of a function of two variables is a curve along which the function has a constant value.

[1] In cartography , a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level . [2] Contour lines are the means of relating the vertical dimension (the third dimension) of the topography of an area to the two-dimensional surface of a topographic map. Contour lines should be visualized as the intersection of the land surface with a series of equally spaced, horizontal planes that pass through this surface. Contour or isarithmic maps connect regions of equal value using contours or isolines to illustrate a smooth, continuous phenomenon. A common contour map is a topographic map , which uses contour lines to show elevation, including steepness and slope. The contour interval of a topographic map is the difference in elevation between successive contour lines. [3] Contour or isarithmic maps can be used to show a variety of phenomena such as precipitation, temperature, atmospheric pressure, or solar radiation. Data used in isarithmic maps are not confined to predefined political or geographic boundaries. Rather, the data's parameters are as varied as its environment. The gradient of the function is always perpendicular to the contour lines.

When the lines are close together the length of the gradient is large: the variation is steep. If adjacent contour lines are of the same line width, the direction of the gradient cannot be determined from the contour lines alone. However if contour lines rotate through three or more widths, or if the lines are numerically labelled, then the direction of the gradient can also be determined from the contour lines. Contour lines are curved or straight lines on a map describing the intersection of a real or hypothetical surface with one or more horizontal planes. The configuration of these contours allows map readers to infer relative gradient of a parameter and estimate that parameter at specific places. Contour lines may be either traced on a visible three-dimensional model of the surface , as when a photogrammetrist viewing a stereo-model plots elevation contours, or interpolated from estimated surface elevations, as when a computer program threads contours through a network of observation points of area centroids. In the latter case, the method of interpolation affects the reliability of individual isolines and their portrayal of slope , pits and peaks. [4] Contents 8 References History The idea of lines that join points of equal value was rediscovered several times.

In 1701, Edmond Halley used such lines (isogons) on a chart of magnetic variation. [5] The Dutch engineer Nicholas Cruquius drew the bed of the river Merwede with lines of equal depth (isobaths) at intervals of 1 fathom in 1727, and Philippe Buache used them at 10-fathom intervals on a chart of the English Channel that was prepared in 1737 and published in 1752. The use of such lines to describe a land surface (contour lines) was studied theoretically by Ducarla in 1771, and Charles Hutton used them when calculating the volume of a hill in 1777. In 1791, a map of France by J. L. Dupain-Triel used contour lines at 20-metre intervals, hachures, spot-heights and a vertical section. In 1801, the chief of the Corps of Engineers, Haxo, used contour lines at the larger scale of 1:500 on a plan of his projects for Rocca d'Aufo.

[6] [7] [8] By around 1843, when the Ordnance Survey started to regularly record contour lines in Great Britain and Ireland, they were already in general use in European countries. Isobaths were not routinely used on nautical charts until those of Russia from 1834, and those of Britain from 1838. [9] [10] [6] When maps with contour lines became common, the idea spread to other applications. Perhaps the latest to develop are air quality and noise pollution contour maps, which first appeared in the USA, in approximately 1970, largely as a result of national legislation requiring spatial delineation of these parameters. In 2007, Pictometry was the first to allow users to dynamically generate elevation contour lines to be laid over oblique images. Types of contour lines Contour lines are often given specific names beginning "iso-" (from Greek ισος (isos), meaning 'equal') according to the nature of the variable being mapped, although in many usages the word "contour line" is most commonly used. Specific names are most common in meteorology, where multiple maps with different variables may be viewed simultaneously.

In general, an isoline is a line along which a variable is held constant. Meteorology Isohyetal map Meteorological contour lines are based on generalization from point data received from weather stations. Weather stations are seldom exactly positioned at a contour line (when they are, this indicates a measurement precisely equal to the value of the contour). Instead, lines are drawn to best approximate the locations of exact values based on the scattered information points available. Meteorological contour maps may present collected data such as actual air pressure at a given time, or generalized data such as average pressure over a period of time, or forecast data such as predicted air pressure at some point in the future Thermodynamic diagrams use multiple overlapping contour sets (including isobars and isotherms) to present a picture the major thermodynamic factors in a weather system. Barometric pressure Isobar map of Western Europe. Troughs are areas of greater variablility, signified by many isolines close together. Ridges are areas where there is little change in pressure over great distances. An isobar (from βαϝος or baros, meaning 'weight') is a line of equal or constant pressure on a graph, plot, or map; an isopleth or contour line of pressure.

More accurately, isobars are lines drawn on a map joining places of equal average atmospheric pressure reduced to sea level for a specified period of time. In meteorology, the barometric pressures shown are reduced to sea level , not the surface pressures at the map locations. The distribution of isobars is closely related to the magnitude and direction of the wind field, and can be used to predict future weather patterns. Isobars are commonly used in television news weather reporting, though more commonly in Europe than in the United States. An isostere is a line of constant atmospheric density. An isoheight or isohypse is a line of constant geopotential height on a constant pressure surface chart. Temperature and related subjects The 10°C mean isotherm in July, marked by the red line, is commonly used to define the Arctic region border An isotherm (from θεϝμη or thermē, meaning 'heat') is a line that connects points on a map that have the same temperature. Therefore, all points through which an isotherm passes have the same temperatures at the time indicated. Generally, isotherms representing 5°C or 10°F temperature differences are used, but any interval may be chosen.

An isogeotherm is a line of equal mean annual temperature. An isocheim is a line of equal mean winter temperature. An isothere is a line of equal mean summer temperature. An isohel (from έλιος or helios, meaning 'sun') is a line of equal or constant solar radiation. Precipitation and air moisture An isohyet or isohyetal line (from ϝετος or huetos, meaning 'rain') is a line joining points of equal precipitation on a map . A map with isohyets is called an isohyetal map. An isohume is a line of constant relative humidity. An isodrosotherm (from δϝοσος or drosos, meaning 'dew', and θεϝμη or therme, meaning 'heat') is a line of equal or constant dew point. An isoneph is a line indicating equal cloud cover. An isochalaz is a line of constant frequency of hail storms. An isobront is a line drawn through geographical points at which a given phase of thunderstorm activity occurred simultaneously. Snow cover is frequently shown as a contour-line map.

Wind An isotach (from ταχ or tach, meaning 'speed') is a line of constant wind speed. In general, an isogon is a line along which an angle is held constant. In meteorology, the term refers to a line of constant wind direction. Freeze and thaw An isopectic line denotes equal dates of ice formation each winter. An isotac denotes equal dates of thawing. Physical geography and Oceanography Elevation and depth Topographic map with isohypses of height Contours are one of several common methods used to denote elevation , altitude and depth on maps. From these contours, a sense of the general terrain can be determined. They are used on a variety of scales, from large-scale engineering drawings and architectural plans, through topographic maps up to continental-scale maps. A map showing the isobath lines of Bear Lake, Idaho, USA "Contour line" is the most common usage in cartography , but isobath for underwater depths on bathymetric maps and isohypse for elevations are also used. The process of drawing isohypse contour lines on a map is called isopletion.

In cartography, a contour interval is any space between contour lines, representing a difference in elevation between the lines. When calculated as a ratio against the map scale, a sense of the hilliness of the terrain can be derived. Magnetism In general, an isogon is a line along which an angle is held constant. In geomagnetism, the term refers to a line of constant magnetic declination (variance of magnetic north from geographic north). Isogonic lines are lines connecting those parts where the declination of the Earth's magnetic field is the same in amount. They are similar to isoclinic lines, which are lines connecting points of equal magnetic inclination. The line drawn through the points of zero magnetic declination is called the agonic line. Oceanography Besides ocean depth, oceanographers use contour to describe diffuse variable phenomena much as meteorologists do with atmospheric phenomena. isobathytherms are lines showing depths of water with equal temperature. isohalines show lines of equal ocean salinity. Isopycnals are surfaces of equal water density. Geology Various geological data are rendered as contour maps in structural geology, sedimentology, stratigraphy and economic geology.

Contour maps are used to show the below ground surface of geologic strata, fault surfaces (especially low angle thrust faults) and unconformities. Isopach maps use isopachs (lines of equal thickness) to illustrate variations in thickness of geologic units. Environmental science In discussing pollution, density maps can be very useful in indicating sources and areas of greatest contamination. Contour maps are especially useful for diffuse forms or scales of pollution. Acid precipitation is indicated on maps with isoplats. Some of the most widespread applications of environmental science contour maps involve mapping of environmental noise, air pollution, soil contamination, thermal pollution and groundwater contamination. Contour lines are being used by wildfire analysts to show temperature change in fire as it burns through different fuel types. This allows researchers to assess temperatures for optimum plant rejuvenation, which in turn allows land managers to assess the scale at which they can do ecological rehabilitation of certain areas. The cost of such projects is extensive and by knowing those areas which will rejuvenate themselves, managers can save money and focus on those areas where the fire had burned the hottest. Social sciences In economics, contour lines can be used to describe features which vary quantitatively over space.

An isochrone shows lines of equivalent drive time or travel time to a given location. An isotim shows equivalent transport costs from the source of a raw material, and an isodopane shows equivalent cost of travel time. Indifference curves are used to show bundles of goods to which a person would assign equal utility. In political science an analogous method is used in understanding coalitions (for example the diagram in Laver and Shepsle's work [12] ) In population dynamics, isocline refers to the set of population sizes at which the rate of change, or partial derivative, for one population in a pair of interacting populations is zero. Isolines can also be used to delineate qualitative differences. An isogloss, for example, is used in mapping the geographic spread of linguistic features. Contour lines are also used in non-geographic charts in economics. An isoquant is a line of equal production quantity, and an isocost shows equal production costs.

Thermodynamics, Engineering, and other sciences Various types of graphs in thermodynamics, engineering, and other sciences use isobars (for showing constant pressure), isotherms (for constant temperature), isochors (for constant specific volume), or other types of iso-lines (or curves), even though these graphs are usually not related to maps. Such iso-lines are useful for representing more than two dimensions (or quantities) on two-dimensional graphs. Common examples in thermodynamics are some types of phase diagrams. An Isocline is generically a line of equal slope. Isoclines are used to solve ordinary differential equations. In interpreting radar images: An isodop is a line of equal Doppler velocity. An isoecho is a line of equal radar reflectivity. Other phenomena isophene: biological events occurring with coincidence such as plants flowering isophote: illuminance History of the National Weather Service History of the National Weather Service Weather.gov > History of the National Weather Service The National Weather Service has its beginning in the early history of the United States. Weather always has been important to the citizenry of this country, and this was especially true during the 17th and 18th centuries.

Weather also was important to many of the Founding Fathers. Colonial leaders who formed the path to independence of our country also were avid weather observers. Thomas Jefferson purchased a thermometer from a local Philadelphia merchant while in town for the adoption of the Declaration of Independence. He also purchased a barometer — one of the only ones in America at the time — a few days later from the same merchant. Incidentally, he noted that the high temperature in Philadelphia, Pa., on July 4, 1776 was 76 degrees. Jefferson made regular observations at Monticello from 1772-78, and participated in taking the first known simultaneous weather observations in America. George Washington also took regular observations; the last weather entry in his diary was made the day before he died. During the early and mid-1800's, weather observation networks began to grow and expand across the United States. Although most basic meteorological instruments had existed for over 100 years, it was the telegraph that was largely responsible for the advancement of operational meteorology during the 19th century. With the advent of the telegraph, weather observations from distant points could be "rapidly" collected, plotted and analyzed at one location.

1800-1899 2006-2009 2010-Current 1849: Smithsonian Institution supplies weather instruments to telegraph companies and establishes extensive observation network. Observations submitted by telegraph to the Smithsonian, where weather maps are created. By the end of 1849, 150 volunteers throughout the United States were reporting weather observations to the Smithsonian regularly. By 1860, 500 stations were furnishing daily telegraphic weather reports to the Washington Evening Star, and as the network grew, other existing systems were gradually absorbed, including several state weather services. 1860: 500 stations are making regular observations, but work is interrupted by the Civil War. 1869: Telegraph service, instituted in Cincinnati, began collecting weather data and producing weather charts. The ability to observe and display simultaneously observed weather data, through the use of the telegraph, quickly led to initial efforts toward the next logical advancement, the forecasting of weather. However, the ability to observe and forecast weather over much of the country, required considerable structure and organization, which could be provided through a government agency.

1870: A Joint Congressional Resolution requiring the Secretary of War "to provide for taking meteorological observations at the military stations in the interior of the continent, and at other points in the States and Territories...and for giving notice on the northern lakes and on the seacoast, by magnetic telegraph and marine signals, of the approach and force of storms" was introduced. Congress passed the resolution and on February 9, 1870, President Ulysses S. Grant signed it into law. A new national weather service had been born within the U.S. Army Signal Service’s Division of Telegrams and Reports for the Benefit of Commerce that would affect the daily lives of most of the citizens of the United States through its forecasts and warnings for years to come. 1870-1880: Gen. Albert J. Myer serves as chief signal officer, directing the new weather service. 1880: Upon the death of Gen. Myer, Gen. William Babcock Hazen takes over as chief signal officer. He serves until his death in 1887. 1887: Upon the death of Gen. Hazen, Maj. Gen.

Adolphus Greely takes over as chief signal officer. He serves until his death in 1891. May 30, 1889: An earthen dam breaks near Johnstown, Pennsylvania. The flood kills 2,209 people and wrecks 1,880 homes and businesses. October 1, 1890: The weather service is first identified as a civilian agency when Congress, at the request of President Benjamin Harrison, passes an act transferring the meteorological responsibilities of the Signal Service to the newly-created U.S. Weather Bureau in the Department of Agriculture. A weather-sensitive sports event of that year: 15th running of the Kentucky Derby. 1891: The secretary of agriculture directs R.G. Dyrenforth to carry out rain-making experiments by setting off explosions from balloons in the air. Weather Bureau becomes responsible for issuing flood warnings to the public; Telegraphic reports of stages of rivers were made at 26 places on the Mississippi and its tributaries, the Savannah and Potomac Rivers. Professor Mark W. Harrington becomes the first chief of the Weather Bureau. He serves until 1895.

1894: William Eddy, using five kites to loft a self-recording thermometer, makes first observations of temperatures aloft. 1895: Secretary of Agriculture J. Sterling Morton appoints Professor Willis Luther Moore chief of the Weather Bureau. Moore served until his resignation in 1913. 1898: President William McKinley orders the Weather Bureau to establish a hurricane warning network in the West Indies. 1900: Cable exchange of weather warnings and other weather information begins with Europe. September, 1900: A devastating hurricane strikes Galveston, Texas, killing more than 6,000 people. The wife of the Galveston Official-in-Charge Isaac Cline and one Weather Bureau employee and his wife are killed in the associated flooding. The Weather Bureau forecasts the storm four days earlier, but not the high tide. 1901: Official three-day forecasts begin for the North Atlantic. At the Weather Bureau Conference in Milwaukee, Wis., Chief Willis Moore observed the Post Office Department was delivering slips of paper with daily forecasts, frost and cold-wave warnings, to everyone's door with the mail.

The one disadvantage to the system was the mail carriers started their routes about 7:00 a.m. and that day's forecast was not issued until 10:00 a.m., so the previous night's forecasts were used. 1902: The Marconi Company begins broadcasting Weather Bureau forecasts by wireless telegraphy to Cunard Line steamers. The Weather Bureau begins collecting flood damage statistics nationally. 1903: Weather sensitive historic events: United States and Panama sign the Canal Treaty; the first automobile trip across the United States is completed from San Francisco to New York City; The Wright brothers make first powered airplane flight at Kill Devil Hill, N.C., after consultation with the Weather Bureau several years earlier for a suitable location to conduct their experiments. 1904: The government begins using airplanes to conduct upper air atmospheric research. 1905: The SS New York transmits the first wireless weather report received on ship at sea. 1907: Weather sensitive historic event: Round-the-world cruise of U.S. "Great White Fleet" including 16 battleships and 12,000 men. 1909: The Weather Bureau begins its program of free-rising balloon observations.

1910: Weather Bureau begins issuing generalized weekly forecasts for agricultural planning; its River and Flood Division begins assessment of water available each season for irrigating the West. 1911: The first transcontinental airplane flight, from New York City to Pasadena, Calif., by C.P. Rogers, in 87 hours and 4 minutes, air time, over a period of 18 days. 1912: As a result of the Titanic disaster, an international ice patrol is established, conducted by the Coast Guard; first fire weather forecast issued. 1913: Professor Charles F. Marvin serves as the new chief of the Weather Bureau, replacing Professor Moore. Marvin serves until his retirement in 1934. 1914: An aerological section is established within the Weather Bureau to meet growing needs of aviation; first daily radiotelegraphy broadcast of agricultural forecasts by the University of North Dakota. 1916: A Fire Weather Service is established, with all district forecast centers authorized to issue fire weather forecasts. The Weather Bureau's fire district forecast center started at Medford, Oregon.

1917: Norwegian meteorologists begin experimenting with air mass analysis techniques which will revolutionize the practice of meteorology. 1918: The Weather Bureau begins issuing bulletins and forecasts for domestic military flights and for new air mail routes. 1919: Navy Aerological Service established on a permanent basis. First Transatlantic flight by U.S. Navy sea plane, with stops in Newfoundland, Azores and Lisbon. 1920: Meteorologists form a professional organization, the American Meteorological Society, which is still active today. 1921: The University of Wisconsin makes a radiotelephone broadcast of weather forecasts, the first successful use of the new medium for weather advisories. 1922: Histories of 500 river stations completed. 1926: The Air Commerce Act directs the Weather Bureau to provide for weather services to civilian aviation; fire weather service formally inaugurated when Congress provides funds for seven fire weather districts. 1927: The Weather Bureau establishes a West Coast prototype for an Airways Meteorological Service. Charles Lindbergh flies alone from Long Island, non-stop, to Paris. The 3,610 mile trip is completed in 33.5 hours.

As on his earlier transcontinental flight, he consulted the Weather Bureau in planning this flight. However, Lindbergh didn't wait for the final confirmation of good weather over the Atlantic. When Weather Bureau officials in New York heard that Lindbergh had left, they expressed surprise because the forecasts indicated that the flight should have been delayed by at least 12 hours. Indeed, Lindbergh ran into problems with fog and rain — as the Weather Bureau had predicted. 1928: The teletype replaces telegraph and telephone service as the primary method for communicating weather information. 1931: The Weather Bureau begins regular 5:00 a.m. EST aircraft observations at Chicago, Cleveland, Dallas and Omaha, at altitudes reaching 16,000 feet. This program spells the demise of "kite stations." 1933: A science advisory group apprizes President Franklin D. Roosevelt that the work of the volunteer Cooperative Observer Program is one of the most extraordinary services ever developed, netting the public more benefits per dollar expended than any other government service in the world. By 2010 the network encompasses more than 11,000 stations. 1934: Dr.

Willis L. Gregg is named chief of the Weather Bureau, replacing Professor Marvin. He served as chief until his death in 1938. The Weather Bureau establishes an Air Mass Analysis Section; 1934-37 "Dust Bowl" drought in southern plains causes severe economic damage. 1935: A hurricane warning service is established. The Smithsonian Institution begins making long-range weather forecasts based on solar cycles; floating automatic weather instruments mounted on buoys begin collecting marine weather data. 1936: The Hoover Dam is completed, a weather sensitive engineering feat. 1937: First official Weather Bureau radio meteorograph, or radiosonde sounding made at East Boston, Mass. This program spells the end for aircraft soundings since balloons average only 50,000 feet altitude. Twelve pilots die flying weather missions. January flood on the Ohio River is the greatest ever experienced, with Ohio River levels exceeding all previous. Cincinnati's 80 foot crest and Louisville's 81.4 foot crest have never been exceeded.

Seventy percent of Louisville under water, 175,000 of its residents flee their homes; the entire city of Paducah, Kentucky, (population 40,000) is evacuated. 1938: President Franklin D. Roosevelt appoints Dr. Francis W. Reichelderfer chief of the Weather Bureau. He served as head of the nation’s weather service for a quarter century — longer than anyone before or since — until his retirement in 1963. 1939: The Weather Bureau initiates automatic telephone weather service in New York City; radio meteorgraphs, or radiosondes, replace all military and Weather Bureau aircraft observations. 1940: The Weather Bureau is transferred to the Department of Commerce. Both the Army and Navy establish weather centers. President Roosevelt orders Coast Guard to man ocean weather stations. 1941: Dr. Helmut Landsberg, the "Father of Climatology," writes the first edition of his elementary textbook entitled, Physical Climatology. Two women are listed among the ranks of observers and forecasters in the Weather Bureau.

1942: A Central Analysis Center, forerunner of the National Meteorological Center, is created to prepare and distribute master analyses of upper atmosphere; Joint Chiefs of Staff establish a Joint Meteorological Committee to coordinate wartime civilian and military weather activities. The Navy gives the Weather Bureau 25 surplus aircraft radars to be modified for ground meteorological use, marking the start of a weather radar system in the U.S. Navy aerologists play key role as U.S. carrier-based Navy planes decimate Japanese fleet in mid-Pacific Battle of Midway Island in early June 1942, turning point in World War II. A cooperative thunderstorm research effort is undertaken by the Weather Bureau, military services, and the University of Chicago. 1944: The decision to invade Normandy on June 6 was based on weather forecasts, which indicated the correct combination of tides and winds. 1945: More than 900 women are employed by the Weather Bureau as observers and forecasters, as a result of filling positions of men during World War II. 1946: The U.S. Weather Bureau selects Cincinnati, Ohio and Kansas City as locations for the nation's first hydrologist-staffed River Forecast Center.

Eventually, 13 RFCs would be established to serve the United States. 1948: USAF Air Weather Service meteorologists issue first tornado warnings from Tinker Air Force Base. Princeton's Institute for Advanced Studies begins research into use of a computer for weather forecasting. Chicago Weather Bureau office demonstrates use of facsimile for map transmission. Truck-mounted campers first used as mobile forecast stations in major forest fires. 1950: The Weather Bureau begins issuing 30-day weather outlooks; authorizes release of "tornado alerts" to the public. 1951: The Severe Weather Warning Center — forerunner of the National Severe Storms Center — begins operation at Tinker Air Force Base, in Oklahoma. World Meteorological Organization established by the U.N. Bureau Chief Riechelderfer elected its first head; Bureau's New Orleans data tabulation unit moves to Asheville, N.C., to become the National Weather Records Center and later the National Climatic Data Center. 1952: The Weather Bureau organizes Severe Local Storms forecasting Unit in Washington, D.C., and begins issuing tornado forecasts.

1954: The Weather Bureau, Navy, Air Force, MIT's Institute for Advanced Study, and the University of Chicago form a Joint Numerical Weather Prediction Unit in Suitland, Maryland. This will become a twice daily routine in 1955, using an IBM 701. The first radar specifically designed for meteorological use, the AN/CPS-9, is unveiled by the Air Weather Service, USAF. 1955: Hurricane Diane floods the Northeast resulting in 187 deaths. Regularly-scheduled operational computer forecasts begun by the Joint Numerical Forecast Unit. The Weather Bureau becomes a pioneer civilian user of computers along with the Census Bureau in Commerce; Bureau begins development of Barotropic model, a first for numerical predictions. 1956: The Bureau initiates a National Hurricane Research Project. 1957-58: The International Geophysical year provides first concerted world wide sharing of meteorological research data. Weather Bureau Chief Dr. Francis Reichelderfer accepts a proposal by Dr. James Brantly of Cornell Aeronautical Laboratories to modify surplus Navy Doppler radars for severe storms observation--the first endeavor to measure motion of precipitation particles by radar.

1958: Weather-related scientific event: Explorer I is launched into space by an Army Redstone Rocket from Cape Canaveral. This satellite discovers the Van Allen Radiation Belts. The National Meteorological Center is established; the first commercial jet passenger flight from New York to Miami by National Airlines. 1959: Major weather-related scientific event: The Army launches Vanguard II from Cape Canaveral, carrying two photocell units to measure sunlight reflected from clouds, demonstrating feasibility of a weather satellite. The Weather Bureau's first WSR-57 weather surveillance radar is commissioned at the Miami Hurricane Forecast Center. The Naval Aerological Service becomes the Naval Weather Service. The Thomas Jefferson and John Campanius Holm awards are created by the Weather Bureau to honor volunteer observers for unusual and outstanding accomplishments in the field of meteorological observations. Both awards still exist today. 1960: The world's first weather satellite, the polar-orbiting TIROS I, successfully launches from the Air Force Missile Test Center at Cape Canaveral, Fla., on April 1. This was followed by the launch of TIROS II on November 11.

The Weather Bureau and NASA invite scientists from 21 nations to participate in the analysis of weather data gathered by TIROS II. In cooperation with the Department of Health, Education and Welfare, Weather Bureau meteorologists issue first advisories on air pollution potential over the eastern United States. 1961: President Kennedy, in his State of the Union address, invites all nations to join the United States in developing an International Weather Prediction Program. The Weather Bureau assumes full responsibility for severe weather forecasting, establishing the National Severe Storms Center in Kansas City; special training begins for Federal Aviation Authority employees to equip them to brief pilots as part of a joint FAA-Bureau program; to USAF Air Weather Service issues first official forecast of clear air turbulence; scientists from 27 countries attend NASA Weather Bureau sponsored international workshop on technique to interpret weather satellite data. 1963: Dr. Robert M. White succeeds Dr. Reichelderfer as chief of the Weather Bureau. He serves in this position until 1965, when he becomes the head of the newly-formed Environmental Science Services Administration, or ESSA, the forerunner of NOAA.

The polar-orbiting weather satellite TIROS III is launched with automatic picture transmission capability, eventually to provide continuous cloud images to over 100 nations. 1964: The secretary of commerce establishes the office for the Federal Coordinator for Meteorology. The National Severe Storms Laboratory is established in Norman, Oklahoma. The American Meteorological Society writes to the Taiwanese Ambassador to the U.S., deploring treatment accorded Mr. Kenneth T.C. Cheng, head of the Taiwan Weather Service, who had been indicted for an incorrect typhoon forecast. The AMS points out that if forecasters were indicted for an incorrect forecast there could soon be a total lack of forecasters. (Minutes of the AMS Council, October 3-4, 1964). 1965: The Environmental Science Services Administration, or ESSA, is created in the Department of Commerce, incorporating the Weather Bureau and several other agencies; Weather Bureau Chief Dr. Robert White is appointed as its first administrator. Dr. George Cressman is named chief of the Weather Bureau and becomes the first director of the National Weather Service, when the agency is renamed in 1970. He serves until his retirement in 1979.

1966: Weather officials from 25 nations meet in London for the First International Clean Air Congress. The National Meteorological Center introduces a computer numerical model capable of making sea level predictions as accurate as those made manually. 1967: Responsibility for issuing air pollution advisories is assigned to the Weather Bureau’s National Meteorological Center. Fire weather forecasts are extended to cover contiguous U.S. 1969: Weather-related historic event: Neil Armstrong, Commander of spacecraft Apollo 11, becomes first man to set foot on the moon. 1970: The Environmental Science Services Administration (ESSA) becomes the National Oceanic and Atmospheric Administration (NOAA), with Dr. Robert White assuming the role of its first administrator. The U.S. Weather Bureau becomes the National Weather Service. 1972: Rainfall from Hurricane Agnes floods the East Coast, killing 105 people. A devastating flash flood in the Black Hills of South Dakota kills 237 people. 1973: The National Weather Service purchases its second generation radar, the WSR-74.

1975: The first "hurricane hunter" Geostationary Operational Environmental Satellite (GOES) is launched into orbit; these satellites with their early and close tracking of hurricanes, greatly reduce the loss of life from such storms. 1976: Real-time operational forecasts and warnings using Doppler radar are evaluated by the Joint Doppler Operational Project, spawning a third Generation Weather Radar (WSR-88D). The Big Thompson Canyon Flood in Colorado kills 139 people. 1977: The success of weather satellites results in the elimination of the last U.S. weather observation ship; real time access to satellite data by national centers advances hurricane, marine and coastal storm forecasts. 1979: Dr. Richard Hallgren is appointed director of the National Weather Services. He serves until his retirement in 1988, when he becomes executive director of the American Meteorological Society. 1979: A Nested Grid Model (NGM) becomes operational; a Global Data Assimilation System (GDAS) developed. AFOS Computer system is deployed, connecting all Weather Service forecast offices.

AFOS is the most ambitious computer network created at the time, setting records for volume of data and number of entry points while supporting full range of word processing and other capabilities. 1980: Mt. St. Helens, a dormant volcano in Washington state, erupts; weather satellites spot eruption and alert FAA. "Dean of the Cooperative Weather Observers," Mr. Edward H. Stoll of Elwood, Nebraska, is honored at the nation's Capitol and meets President Jimmy Carter at the White House. Mr. Stoll had faithfully served as a Cooperative Observer since October 10, 1905. Various "hot weather topics" become of general public concern, such as the El Niño/Southern Oscillation as a factor in U.S. weather, and global warming. 1981: Weather-related science event: World's first reusable space shuttle, Columbia, is launched, completing its mission three days later. 1982: El Chicon volcano erupts in Mexico; NOAA polar weather satellites track movement of its cloud around the earth as a possible global climate impact. 1984: The National Weather Service provides special forecast for the Olympic Games in Los Angeles.

Weather-related event: First successful solo balloon crossing of the Atlantic by pilot Joe Kittinger, 83 hours and 45 minutes. September 11-13: The first official Air Transportable Mobile Unit (ATMU) dispatches to the Shasta-Trinity National Forest wildfire. The ATMU is dispatched by plane from Redding, California while the forecaster is flying from Sacramento, Calif. These mobile fire units are deployed nationwide in 1987. ATMUs permit NWS forecasters to set up remote observing and forecasting offices anywhere in the world within hours of a request for on-site fire weather support. 1985: Harvard's Blue Hill Observatory celebrates 100 years of continuous monitoring of the atmosphere. President Ronald Reagan awards Dr. Helmet Landsberg the National Medal of Science, the most prestigious service award a civilian can receive. 1986: The Voyager aircraft completes the first nonstop, non-refueled flight around the world in nine days with assistance of continuous weather support from retired, volunteer and current NWS employees. 1988: The National Weather Service operates several remote forecast operations in Yellowstone National Park to assist in fighting week-long wildfire.

The National Hurricane Center provides continuous advisories and early forecast on movement of giant hurricane Gilbert to assist Caribbean and U.S. coastal areas with evacuation plans. 1987-88 major drought experienced by nation's midsection, with some of lowest river levels in 50 years observed on the Mississippi. Dr. Richard Hallgren retires as NWS director to become executive director of the American Meteorological Society. Dr. Elbert W. “Joe” Friday, Jr. becomes director of the National Weather Service. He serves until 1997. 1989: U.S. assists clean-up efforts following San Francisco Earthquake with mobile forecast unit. Miami Hurricane Center plays central role in limiting loss of life from gigantic Hurricane Hugo which causes $7 billion damage. Eight year national plan for the modernization and restructuring of the National Weather Service is announced. The massive $4.5 billion overhaul of the agency from will last a decade and change the way the agency operates, resulting in improved capabilities to protect lives and livelihoods.

To modernize its operations, the NWS developed and implemented five major technologies: Automated Surface Observing System, or ASOS, which replaced manual weather observations Next Generation Weather Radar, or NEXRAD, a network of advanced Doppler radars that contributed to increased lead times in predicting severe weather events, such as tornadoes, hail, and flash floods A new series of satellites that provided improved, all-weather data for longer-term forecasting Advanced computer systems that increased the computing power to support National Centers tenfold Advanced Weather Interactive Processing System, or AWIPS, which allowed communication among forecast offices and distribution of centrally collected data as well as offered field forecasters access to the data provided by the other new technologies 1990: The National Meteorological Center procures and installs a supercomputer, the Cray Y-MP8, to run higher resolution and more sophisticated numerical weather production models. The National Weather Service exercises the contract option for full scale production with the Unisys Corporation for production of 165 Next General Radar (NEXRAD) units and more than 300 display subsystems.

The explosive growth of technology led to the development of NEXRAD, a joint project of the Departments of Commerce, Transportation and Defense to meet their common radar needs. 1991: Automated Surface Observing System contract, a key element in NOAA's modernization of its NWS, awarded to AAI Corporation of Hunt Valley, Md., on February 19. 1992: Twenty-two of the planned 115 modernized Weather Forecast Offices (WFO) were built or remodeled during the year, with 12 NWS radars installed. Of a programmed 1,700 ASOS units, 151 were installed and 13 commissioned. Hurricane Iniki struck the Hawaiian island of Kauai killing seven and Hurricane Andrew devastates Florida and Louisiana. 1993: "Year of Water" — record floods inundate the Midwest; the National Weather Service earns the U.S. Commerce Department's highest award, a gold medal, for performance during the flooding. Advanced Weather Interactive Processing System (AWIPS) contract awarded to PRC, Inc., of McLean, Va. AWIPS will rapidly analyze weather data and distribute it nationwide.

The 100th new Doppler weather radar is installed. The blizzard of '93 deposited enough precipitation in one weekend to drastically change the spring hydrologic outlook. An international training facility was dedicated at the National Meteorological Center. Two scientists develop a new method of processing atmospheric data needed for global forecasting and five meteorologists from Alaska design a state-of-the-art computer network used to improve forecasting capabilities in Alaska. 1994: Dr. Elbert W. Friday, Jr. was honored as Federal Executive of the Year. Vice President Al Gore launches NOAA Weather Radio initiative to increase transmitter coverage to 95 percent of the population. The new Cray C90 supercomputer was dedicated providing for faster and more accurate forecasts. NOAA and the EPA launched an experimental Ultraviolet (UV) Exposure Index. 1995: The National Tsunami Hazard Mitigation Program (NTHMP), the nation’s community-focused program to improve tsunami mitigation and preparedness of at-risk areas within the United States and its territories is created. NWS launches Internet Service Interactive Weather Information Network—IWIN. 1996: NWS provides forecasting support for Atlanta Olympics. Scientist make the first dual Doppler tornado intercept.

A team of government and university scientists and student volunteers for the first time observe a tornado close-up with dual high-resolution Doppler radars, providing a never-before-seen two-dimensional view of a full-blown tornado. The team scanned the slow moving twister for 10 minutes with the two Doppler radars mounted on flatbed trucks. 1997: Nationwide WSR-88D radar network is fully deployed. Red River of the North Flood causes 11 deaths and $3.5 billion in damages. Subsequent evaluation of NWS services led to service improvement in hydrologic products including explicit consideration of uncertainty in forecasting. Dr. Robert S. Winokur appointed acting director of the National Weather Service. 1998: Brig. Gen. John J. “Jack” Kelly, Jr., USAF (ret.), appointed director of the National Weather Service. He serves until his retirement in 2004. 2000: The Advanced Weather Interactive Processing System (AWIPS), a high-tech, interactive weather computer and communications system has been installed in 152 National Oceanic and Atmospheric Administration sites across the country. AWIPS provides significant improvements in weather- and flood-related services.

With the completion of AWIPS the formal end of the NWS Modernization and associated restructuring is declared, completing a decade-long effort to revamp weather services and significantly improve weather forecasting. StormReady®, a new national program designed to better prepare for tornadoes and other types of severe weather, is unveiled. By 2011 there are more than 1,800 StormReady sites in 48 states, as well as Puerto Rico and Guam. 2001: President George W. Bush issues the first presidential proclamation for the National Hurricane Preparedness week. TsunamiReady™, a national program designed to help cities, towns, counties, universities and other large sites in coastal areas reduce the potential for disastrous tsunami-related consequences, is unveiled. By 2011 there are more than 90 TsunamiReady sites in 10 states, Puerto Rico and Guam and the Northern Mariana Islands. 2002: NWS partners with university and private sector meteorologists to provide accurate forecasts for athletes and spectators at 2002 Olympic Winter Games in Salt Lake City, Utah.

2003: National Academy of Sciences report, “Fair Weather: Effective Partnerships in Weather and Climate Services” released to advise NOAA on approaches it should take to improve relationships with private sector. 2004: Brig. Gen. David L. Johnson, USAF (ret.), appointed director of the National Weather Service. He serves until his retirement in 2007. NOAA policy on Partnerships in the Provision of Environmental Information is adopted in response to the 2003 Academy of Science study. Tsunami readiness in the United States is strengthened after a magnitude 9.0 earthquake strikes in the Indian Ocean and tsunami waves kill over 230, 000 people around the Indian Ocean basin. Congress passes the Tsunami Warning and Education Act authorizing NOAA to strengthen its tsunami detection, forecast, warning and mitigation programs. 2005: Hurricane Katrina makes landfall in southeast Louisiana on August 29, resulting in devastation and loss of life of historic proportions along the Gulf Coast. Katrina results in an estimated $125 billion in damage/costs — making it the most expensive natural disaster in U.S. history — and approximately 1,833 deaths — the highest U.S.

total since the 1928 major hurricane in southern Florida. Hurricane Rita hits the Texas-Louisiana border coastal region in September, creating significant storm surge and wind damage along the coast, and some inland flooding. Prior to landfall, Rita reached the third lowest pressure (897 mb) ever recorded in the Atlantic basin. Rita results in an estimated $16.0 billion in damage/costs and 119 deaths — mostly indirect. Hurricane Wilma hits southwest Florida in October, resulting in strong, damaging winds and major flooding across southeastern Florida. Prior to landfall, as a Category 5 hurricane, Wilma sets a record for the lowest pressure (882 mb) ever recorded in the Atlantic basin. Wilma results in an estimated $16.0 billion in damages/costs and 35 deaths. Overall, the 2005 Atlantic hurricane season set several records. There were 28 named storms (storms with sustained winds of at least 39 miles per hour). In addition, there were an unprecedented 14 hurricanes, of which seven were major hurricanes (Category 3 or better on the Saffir-Simpson Scale).

Three category 5 storms (sustained winds of 156 miles per hour or more) formed in the Atlantic Basin for the first time in a single season (Katrina, Rita, and Wilma). Four major hurricanes and three tropical storms made landfall in the U.S., with an eighth storm (Ophelia) brushed brushing the North Carolina coast. 2006: Severe flooding occurs over portions of the Northeast in June due to several weeks of heavy rainfall, affecting six states and resulting in over $1 billion in damage/costs and at least 20 deaths. December 13 marks the 30th anniversary of the nation's only federally funded weather telecast. Known as “Alaska Weather,” the program, broadcast live across the state every night at 5:30 p.m. from KAKM-TV, the PBS station in Anchorage, is a partnership between public broadcasting and NWS. 2007: For nearly two weeks in January, overnight temperatures over a good portion of California dipped into the 20's, destroying numerous agricultural crops; with citrus, berry, and vegetable crops most affected. An estimated $14 billion in damage/costs are reported.

NWS activated its newest weather and climate supercomputers — IBM machines capable of processing 14 trillion calculations per second at maximum performance and ingest more than 240 million global observations daily. The new computers increased the computational might used for the nation's climate and weather forecasts by 320 percent. NWS implements the Enhanced Fujita scale to rate tornadoes, replacing the original Fujita Scale. The EF scale will continue to rate tornadoes on a scale from zero to five, but ranges in wind speed will be more accurate with the improved rating scale. In response to customer demand for climate information at the local level, NOAA’s National Weather Service has launched a new local three-month temperature outlook product for the continental United States. NWS teams with 2007 Iditarod sled dog race to showcase for four newly designated StormReady® communities. For the first time, mushers raced through four trail communities — Anchorage, Wasilla, McGrath, and Nome — carrying the StormReady distinction.

NWS implements a new Heat/Health Watch Warning System in the cities of San Francisco, Oakland, and San Jose, as well as surrounding Bay communities of Redwood City, Palo Alto, Sunnyvale, Santa Clara, Gilroy, Fremont, Alameda, Berkeley, Richmond, and El Cerrito. They join 18 other metropolitan areas in the United States using this system as guidance for issuing excessive heat watches, excessive heat warnings and heat advisories. Dr. John L. “Jack” Hayes appointed director of the National Weather Service. NWS transitions from county-based to new storm-based warnings, issuing more geographically specific warnings for tornadoes, severe thunderstorms, floods, and marine hazards. A series of three storms affected the Pacific Northwest between December 1 and 3, 2007, resulting in 11 fatalities and an estimated $1 billion in damage. 2008: The United States tsunami detection array is complete with 39 Dart stations positioned around the Pacific basin, western Atlantic and Caribbean Sea. Hurricane Ike makes landfall in Texas, as the largest (in size) Atlantic hurricane on record, causing considerable storm surge in coastal Texas and significant wind and flooding damage in 10 other states.

Estimated damage exceeds $27 billion. Ike results in 112 deaths. The Super Tuesday Tornado Outbreak of February 5-6 results in 57 fatalities in four states. It is the second largest February tornado outbreak since 1950 in terms of fatalities and the largest since May 31, 1985. Nenana, Alaska, Receives Nation’s 1,000th NOAA Weather Radio Transmitter. 2009: Drought conditions occurred during much of the year across parts of the Southwest, Great Plains, and southern Texas causing an estimated $5 billion in agricultural losses in numerous states. The largest agriculture losses occurred in Texas and California. NWS completed implementation of the final phase of a nine-year, $180 million contract by installing the newest generation of IBM supercomputers for weather and climate prediction. The new supercomputers, based on IBM Power 575 Systems, are four times faster than the previous system, with the ability to make 69.7 trillion calculations per second. Higher computation speed allows meteorologists to rapidly refine and update severe weather forecasts as dangerous weather develops and threatens U.S. communities.

Devastating floods affect the southeast U.S., as copious moisture drawn into the region from the Atlantic and Gulf of Mexico produced showers and thunderstorms from September 18-23. Rainfall amounts across the region totaled 5-7 inches, with locally higher amounts near 20 inches. The northern two-thirds of Georgia, Alabama, and southeastern Tennessee were hardest hit with the southeasterly low-level winds providing favorable upslope flow. Flash flood and areal flooding were widespread, with 11 fatalities were directly attributed to this flooding. 2010: NWS unveiled a new hurricane scale this season called the Saffir-Simpson Hurricane Wind Scale. The scale keeps the same wind speed ranges as the original Saffir-Simpson Scale for each of the five hurricane categories, but no longer ties specific storm surge and flooding effects to each category. GOES-15, launched on March 4, 2010, from Cape Canaveral, Fla., joining three other NOAA operational GOES spacecraft that help the agency's forecasters track life-threatening weather.

Record-breaking rain struck Kentucky and the Tennessee Valley on May 1-2, resulting in widespread, devastating flash flooding across much of western and middle Tennessee, including the greater Nashville area. The heavy rain also resulted in unprecedented flooding along the Cumberland River and its tributaries. There were 26 fatalities directly attributed to the flooding, 11 of which were in greater Nashville. Preliminary estimates of property damage were in excess of $2 in greater Nashville alone. 2011: 2011 saw a record-breaking number of 10 separate weather, water and climate disasters, each with an economic loss of $1 billion or more. These included the Groundhog Day Blizzard of Jan 29-Feb 3, several devastating tornado outbreaks — including the one that produced an EF-5 tornado struck Joplin, Mo., which resulted in at least 160 deaths, making it the deadliest single tornado to strike the U.S. since modern tornado record keeping began in 1950 — and river flooding along the Mississippi, Missouri and Souris Rivers.

NWS launches a comprehensive initiative to build a Weather-Ready Nation to make America safer by saving more lives and protecting livelihoods as communities across the country become increasingly vulnerable to severe weather events, such as tornado outbreaks, intense heat waves, flooding, active hurricane seasons, and solar storms that threaten electrical and communication systems. The initiative is focused on helping people make better decisions with better information and will require not only improvements in the science and technology of the modernization era, but also the integration of social sciences and the improvements in partnership with other government agencies, researchers, and the private sector. NWS ranks in the top 15 percent of federal agencies for customer satisfaction, according to a new public survey. With an essential public safety mission, the agency rated 84 on a scale of 0 to 100 – a score considered “excellent” by independent survey firm Claes Fornell International (CFI). Hurricane Irene makes landfall over coastal N.C. before moving northward along the Mid-Atlantic Coast and causing torrential rainfall and flooding across the Northeast. Wind damage in coastal N.C., Va., and Md.

was moderate with considerable damage resulting from falling trees and power lines, while flooding caused extensive flood damage across N.J., N.Y., and VT. More than seven million homes and businesses lost power during the storm. Numerous tornadoes were also reported in several states further adding to the damage. Over $7.0 billion in damages/costs; and at least 45 deaths were reported. NWS began upgrading its network of Doppler radars throughout the nation with dual-polarization (Dual-Pol) capability, resulting in better estimation of heavy rainfall amounts in flooding events, improved hail detection in severe thunderstorms, and improved classification of precipitation types. Dual-Pol radar has the potential to improve forecasts and warnings and reduce the impact of hazardous weather on transportation. The upgrades are scheduled to be completed in early 2013. NWS began using a sophisticated forecast model that substantially improves predictions of space weather impacts on Earth. Better forecasts offer additional protection for people and the technology-based infrastructure we use daily. The National Research Council completes the first phase of a study on the NWS Modernization and Associated Restructuring effort of the 1990s.

The NRC report concludes that the framework left in place from the modernization of the 1990s “allows and encourages the continued evolution of National Weather Service technology, and to some extent the workforce composition and culture.” 2013: Dr. Louis W. Uccellini becomes the 16th Director of the National Weather Service

Question: An isobront is a line on a map joining points where what type of weather occurs simultaneously?
Answer: THUNDERSTORM