Editing Weather forecasting (section)

===Persistence===
The simplest method of forecasting the weather, persistence, relies upon today's conditions to forecast tomorrow's. This can be valid when the weather achieves a steady state, such as during the summer season in the tropics. This method strongly depends upon the presence of a stagnant weather pattern. Therefore, when in a fluctuating pattern, it becomes inaccurate. It can be useful in both short- and long-range forecast|long range forecasts.<ref>University of Illinois at Urbana-Champaign. [http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fcst/mth/prst.rxml "Persistence Forecasting: Today equals Tomorrow"] {{Webarchive|url=https://web.archive.org/web/20070220120718/http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fcst/mth/prst.rxml |date=February 20, 2007 }}. Retrieved February 16, 2007.</ref>