How to Decipher the Weather Forecast
Each morning, your daily newspaper or favorite
morning news show features a weather forecast. If you’re like most
people, you just want to know, is it going to rain or not? These weather
reports attempt to predict the weather both for today as well as several
days out. By learning how to decipher the weather forecast, you can
start making your own predictions. Instead of relying on the summaries
offered by the newspaper or weatherman, you can look at the weather maps
and come to your own conclusions.
In order to make an accurate weather forecast, you must have access to
weather data. This information often comes in the form of a weather map
such as a surface analysis map. For example, this type of map will show
an outline of the United States along with colored lines and symbols
representing pressure systems. “H” stands for a high-pressure system and
“L” stands for a low-pressure system.
Reading a Weather Forecast
So, what does it mean if there’s an “H” or “L” hovering over your area?
In general, high pressure indicates fair weather while low pressure
indicates some form of precipitation such as rain, snow, dew, or hail.
The colored lines that you see in the weather report are fronts. Fronts
can be cold, warm, occluded, or stationary. A cold front is represented
by a blue line with blue triangles while warm fronts feature red lines
with red semi-circles. These shapes point in the direction that the
front is moving.
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Occasionally, a cold front will overtake a warm front and become an
occluded front. This type of front is represented by a purple line and
is often associated with more severe weather events such as
Stationary fronts occur when two air masses aren’t moving. These fronts
mean extended periods of weather events because the system isn’t going
anywhere. Stationary fronts are represented by a blend of both blue and
red lines with blue triangles pointing one way and red semi-circles
pointing the other way.
Predicting Your Weather
When looking at a weather forecast and high- and low-pressure systems,
you’ll also want to check the isobars. Isobars are the plain black lines
that curve and extend their way from the center of the pressure system
outward. Isobars indicate areas of equal pressure. Because air moves
from high-pressure areas to low-pressure areas, wind is created. By
looking at the distance between isobars, you can make an educated
prediction about wind strength. The winds will be much stronger in
sections that have close isobar lines.
Meteorologists use other data in addition to looking at the pressure
systems in order to make an extended weather forecast. However, by
understanding the basics of high and low pressure and learning how to
read them on a map, you can quickly determine the weather forecast at a
glance. If you see an “H” sitting over your city, you’ll know that the
day should be a nice one. If you see an “L,” you might want to pack your
umbrella or snow gear.
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