74
Sunny
Partly Cloudy
Cloudy
Rainy
Snowy
Pressure
increases for
a sustained
period of
time
Pressure
increases
slightly, or
initial power up
Pressure
decreases
slightly
Pressure
decreases for
a sustained
period of
time
Pressure
decreases for a
sustained period
of time and
temperature is
below freezing
Table 12: Weather forecasting summarization
Note:
When the pressure decreases dramatically, the rainy icon will flash
to indicate stormy.
When the pressure decreases dramatically and the temperature is
below freezing, the snowy icon will flash to indicate blizzard.
5.14.1
Storm Alert
If there is a rapid drop in barometric pressure, the forecast icon will flash.
5.14.2
Weather Forecasting Description and Limitations
In general, if the rate of change of pressure increases, the weather is generally
improving (sunny to partly cloudy). If the rate of change of pressure decreases,
the weather is generally degrading (cloudy, rainy). If the rate of change is
relatively steady, it will read partly cloudy.
The reason the current conditions do not match the forecast icon is because the
forecast is a prediction 24-48 hours in advance. In most locations, this
prediction is only 70% accurate and it is a good idea to consult the National
Weather Service for more accurate weather forecasts. In some locations, this
prediction may be less or more accurate. However, it is still an interesting
educational tool for learning why the weather changes.
The National Weather Service (and other weather services such as Accuweather
and The Weather Channel) have many tools at their disposal to predict weather
conditions, including weather radar, weather models, and detailed mapping of
ground conditions.
