Editing Weather map (section)

=== 20th century ===
[[file:US Navy 030209-N-2972R-079 Illustrator Draftsman designs a training slide with the assistance of a light table.jpg|thumb|Light tables were important to the construction of surface weather analyses into the 1990s]]

The use of frontal zones on weather maps began in the 1910s in [[Norway]]. Polar front theory is attributed to [[Jacob Bjerknes]], derived from a coastal network of observation sites in [[Norway]] during [[World War I]]. This theory proposed that the main inflow into a cyclone was concentrated along two [[convergence zone|lines of convergence]], one ahead of the low and another trailing behind the low. The convergence line ahead of the low became known as either the steering line or the warm front. The trailing convergence zone was referred to as the [[squall line]] or cold front. Areas of clouds and [[rain]]fall appeared to be focused along these convergence zones. The concept of frontal zones led to the concept of [[air mass]]es. The nature of the three-dimensional structure of the cyclone would wait for the development of the upper air network during the 1940s.<ref name="OU">University of Oklahoma. [http://weather.ou.edu/~metr4424/Files/Norwegian_Cyclone_Model.pdf The Norwegian Cyclone Model.] {{webarchive|url=https://web.archive.org/web/20060901163934/http://weather.ou.edu/~metr4424/Files/Norwegian_Cyclone_Model.pdf |date=2006-09-01 }} Retrieved on 2007-05-17.</ref> Since the leading edge of air mass changes bore resemblance to the [[military front]]s of [[World War I]], the term "front" came into use to represent these lines.<ref>{{cite web|author=Bureau of Meteorology|year=2010|url=http://www.bom.gov.au/info/ftweather/page_6.shtml|title=Air Masses and Weather Maps|access-date=2010-02-06|publisher=Commonwealth of Australia}}</ref>
The United States began to formally analyze fronts on surface analyses in late 1942, when the WBAN Analysis Center opened in downtown [[Washington, D.C.]]<ref>{{cite web|author=[[Weather Prediction Center]]|url=http://www.wpc.ncep.noaa.gov/html/historyNMC.shtml|title=A Brief History of the Weather Prediction Center|access-date=2014-07-01|date=2007-03-01|publisher=[[National Oceanic and Atmospheric Administration]]}}</ref>

In addition to surface weather maps, weather agencies began to generate constant pressure charts. In 1948, the United States began the Daily Weather Map series, which at first analyzed the 700 hPa level, which is around {{convert|3000|m|ft}} above [[sea level]].<ref>{{cite web|url=http://docs.lib.noaa.gov/rescue/dwm/1948/19480701.djvu|author=[[United States Weather Bureau]]|title=Daily Weather Map|date=1948-07-01|access-date=2010-02-06|publisher=[[United States Department of Commerce]]}}</ref> By May 14, 1954, the 500 hPa surface was being analyzed, which is about {{convert|5520|m|ft}} above sea level.<ref>{{cite web|url=http://docs.lib.noaa.gov/rescue/dwm/1954/19540514.djvu|title=Daily Weather Map|date=1954-05-14|author=[[United States Weather Bureau]]|access-date=2010-02-06|publisher=[[United States Department of Commerce]]}}</ref> The effort to automate map plotting began in the United States in 1969,<ref>{{cite web|publisher=[[Environmental Science Services Administration]]|author=National Meteorological Center|date=January 1969|url=http://www.ncep.noaa.gov/officenotes/NOAA-NPM-NCEPON-0001/013FD50A.pdf|title=Prospectus for an NMC Digital Facsimile Incoder Mapping Program|access-date=2007-05-05}}</ref> with the process complete in the 1970s. A similar initiative was started in India by [[India Meteorological Department|Indian Meteorological Department]] in 1969.<ref>{{Cite news|url=https://www.thehindu.com/archives/from-the-archives-july-12-1969-forecasts-with-aid-of-computer/article28388284.ece|title=From the Archives (July 12, 1969): Forecasts with aid of computer|date=2019-07-12|work=The Hindu|access-date=2019-07-18|language=en-IN|issn=0971-751X}}</ref> [[Hong Kong]] completed their process of automated surface plotting by 1987.<ref>{{cite web|date=2009-09-03|author=Hong Kong Observatory|url=http://www.weather.gov.hk/wservice/tsheet/computer.htm|title=The Hong Kong Observatory Computer System and Its Applications|access-date=2010-02-06|publisher=The Government of the Hong Kong Special Administrative Region|archive-url=https://web.archive.org/web/20061231001802/http://www.weather.gov.hk/wservice/tsheet/computer.htm|archive-date=2006-12-31|url-status=dead}}</ref>

By 1999, computer systems and software had finally become sophisticated enough to allow for the ability to underlay on the same workstation satellite imagery, radar imagery, and model-derived fields such as atmospheric thickness and frontogenesis in combination with surface observations to make for the best possible surface analysis. In the United States, this development was achieved when [[Intergraph]] workstations were replaced by n-[[Advanced Weather Interactive Processing System|AWIPS]] workstations.<ref>{{cite web|author=[[Hydrometeorological Prediction Center]]|year=2000|url=http://www.wpc.ncep.noaa.gov/html/Accomplish99/Accomplish99.html|title=Hydrometeorological Prediction Center 1999 Accomplishment Report|access-date=2007-05-05|publisher=[[National Oceanic and Atmospheric Administration]]}}</ref> By 2001, the various surface analyses done within the National Weather Service were combined into the Unified Surface Analysis, which is issued every six hours and combines the analyses of four different centers.<ref name="DR">{{cite web|author=David M. Roth|publisher=[[Hydrometeorological Prediction Center]]|date=2006-12-14|url=http://www.wpc.ncep.noaa.gov/sfc/UASfcManualVersion1.pdf|title=Unified Surface Analysis Manual|access-date=2006-10-22}}</ref> Recent advances in both the fields of [[meteorology]] and [[geographic information system]]s have made it possible to devise finely tailored products that take us from the traditional weather map into an entirely new realm. Weather information can quickly be matched to relevant geographical detail. For instance, icing conditions can be mapped onto the road network. This will likely continue to lead to changes in the way surface analyses are created and displayed over the next several years.<ref>{{cite web|author=S. A. Saseendran, L. Harenduprakash, L. S. Rathore and V. S. Singh|url=http://www.gisdevelopment.net/application/environment/conservation/envm0004.htm|title=A GIS application for weather analysis and forecasting|access-date=2007-05-05|date=2004-12-05|publisher=GISDevelopment.net}}</ref>