WW2010 University of Illinois

 WW2010

 welcome

 > online guides

 archives

 educational cd-rom

 current weather

 index

 Online Guides

 introduction

 > meteorology

 remote sensing

 projects, activities

 Meteorology

 introduction

 air masses, fronts

 clouds, precipitation

 el nino

 forces, winds

 hurricanes

 hydrologic cycle

 light, optics

 midlatitude cyclones

 severe storms

 > weather forecasting

 Weather Forecasting

 introduction

 > methods

 surface features

 temperatures

 precipitation

 Methods

 persistence

 > trends

 other methods

 User Interface

 graphics
 > text

 NOTE: We've guessed that you're not using a client that supports colored tables and have tried to compensate. Low graphics mode looks much better on clients that do... we recommend switching to Netscape 3.0 or Microsoft Internet Explorer.
.
Trends Method
using mathematics

The trends method involves determining the speed and direction of movement for fronts, high and low pressure centers, and areas of clouds and precipitation. Using this information, the forecaster can predict where he or she expects those features to be at some future time. For example, if a storm system is 1000 miles west of your location and moving to the east at 250 miles per day, using the trends method you would predict it to arrive in your area in 4 days.

Mathematics
(1000 miles / 250 miles per day = 4 days)

Using the trends method to forecast only a few hours into the future is known as "Nowcasting" and this method is frequently used to forecast precipitation. For example, if a line of thunderstorms is located 60 miles to your northwest and moving southeast at 30 miles per hour, you would predict the storms to arrive in your area in 2 hours. Below is an example of using the trends method to forecast the movement of a cold front. Initially, the cold front moved 800 miles during the first 24 hours, from the central Plains to the Great Lakes.

Using the trends method, you would predict this weather system to move another 800 miles in the next 24 hours, reaching the East Coast of the United States. The trends method works well when systems continue to move at the same speed in the same direction for a long period of time. If they slow down, speed up, change intensity, or change direction, the trends forecast will probably not work as well.

persistence
 Terms for using data resources. CD-ROM available. Credits and Acknowledgments for WW2010. Department of Atmospheric Sciences (DAS) atthe University of Illinois at Urbana-Champaign.

other methods