The National Weather Service manages hundreds of weather stations across the cou
ID: 298053 • Letter: T
Question
The National Weather Service manages hundreds of weather stations across the country that observes meteorological variables like air temperature, dew point temperature, and wind direction. These observations are plotted as station models on surface weather maps. Meteorologists use these maps to analyze and forecast the weather by identifying areas of high and low atmospheric pressure, weather fronts, and significant weather events.
Station Models
Station models provide a means of presenting a lot of information in a fairly concise manner. The most common meteorological variables plotted on a station model are atmospheric pressure, air temperature, dew point temperature, wind speed and direction, cloud cover, and present weather. Many other variables can be entered, such as cloud types and cloud heights. On a weather map, station models are centered on the latitude and longitude of the city where the observations were recorded.
The key to understanding a station model is in understanding the shorthand used to draw the model. According to the charts, in the station model example (figure below), the temperature is 76 degree Fahrenheit, the dew point temperature is 55 degree Fahrenheit, and the wind direction is northeast (the wind flag points in the direction the wind is coming from) at about 20 knots. The atmospheric pressure is 1013.8 mb, and has increased and then decreased, and is now lower by 0.3 mb than three hours ago. The cloud cover is completely overcast, and it is raining.
*Cloud cover is typically given in eighths (labels for above would be clear, 1/8 through 8/8, and obscured).
Atmospheric pressure readings are coded to save space. The leading 10 or 9 is dropped from the observation, and the last 3 digits (which implies a decimal place) are used on the station model. The units are millibars (mb).
Atmospheric Pressure Decoding Guidelines:
• If the first digit on the model is 5, then add a 10
Example: 075 would be decoded as 1007.5 mb
• If the first digit on the model is >5, then add a 9
Example: 613 would be decoded as 961.3 mb
Pressure change over the past 3 hours is given on the station model on the right side next to the pressure tendency number. The following chart decodes the line segments:
Decode the following station models:
What is the dew point temperature at location H? ____________ Fahrenheit
What is the decoded atmospheric pressure for location A? _________ mb
What is the decoded atmospheric pressure for location B? _________ mb
Explanation / Answer
1. The temperature at location D is 45 degree Fahrenheit as seen on the diagram since the upper left side on the station model represents the air temperature in degree Fahrenheit.
The dew point temperature at location H is 45 degree Fahrenheit since the lower left side of the station model shows the temperature of dew point in Fahreinheit.
Since if the first digit of the pressure given on the station model is less than or equal to 5 then 10 is added to the pressure value given. Here the pressure given on the station model is 087 which is less than 5 that means 10 will be added to this number which will give the resulting value of pressure 1008.7 mb.
For location B, the given pressure value is 978 and the first digit is greater than 5 so 9 will be added to this value and will give the resulting value of pressure 997.8mb.
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