Part C: Local Weather Stories
Source: National Weather Service
As you learned in the previous labs, multiple factors work together to create the weather in a given location and time period. Most people probably haven't thought much about how fast, or in which direction, weather systems travel, nor how quickly the weather can change in a single day or week. In this lab, you will see how variable weekly weather can be, and you will consider the factors that make it so changeable.
You will also download and analyze temperature and precipitation patterns for one city over a number of years and see how climate patterns emerge from many years worth of weather data.
When we observe weather, we usually report temperature, precipitation, cloudiness, humidity, air pressure, wind speed, and direction. Weather observations are made by many systems, both from the ground and from above. These systems include: automated instruments, satellites, trained professional observers, as well as volunteers. If you'd like to become a volunteer weather watcher you can join the CoCoRaHS network.
Begin the lab with this question: What is weather, and how does it differ from climate? Try your hand at using what you have learned so far in this module to sort out weather from climate. Choose one of the options listed here, either download and print the strips (below) or work with the interactive weather and climate sentence page.
- Download and print the following sentence strips.
- Cut apart the sentence strips.
- Sort them into two groups: weather or climate. When you are done sorting, write out and add two more statements of your own to each set.
- You should wear your raincoat today; I think it is going to rain.
- My grandfather told me that 40 years ago we used to get a lot more snow in December, now we don't see snow until mid-January.
- It seems like we had a very short summer here in Idaho this year.
- Springtime is the rainy season here in Arizona.
- We had hail the size of golf balls in last week's storm.
- I've noticed that many new types of plants grow here in North Dakota; the winters just aren't as cold as they used to be 30 years ago.
- Every summer we have a picnic by the beach in July; it is always warm and breezy.
- This afternoon was hot; I think we set a new record.
- We should go sailing this afternoon; it is breezy this morning, and the wind is supposed to come up later today.
Track a storm system
Get a feel for the rate at which typical weather systems travel over a week's time by viewing a slide show of one week's weather. Examples of these systems are shown on the weather map, upper-right, as blue high (H) and red low (L) pressure regions, and their related frontal zones. Play the entire slideshow, below, see all the slides. Then play it again one slide at a time and examine it more closely. Choose one H (high) or L (low), or a front (blue or red lines), and follow the high or low with your pencil tip as it moves across the map, through space and time. Note: the slide show can be played full screen mode.
For more information about what the symbols mean (beyond the scope of this lesson), read this page: Weather Map Symbols.
In this exercise, you will get a sense of how fast storm systems move across the contiguous (lower 48) United States, by recording and drawing the storm tracks of the two weather systems shown in the slide show above.
- Print out a blank outline map of the United States. (shown right)
- Using the printed maps from the link below or the online maps in the animation above, locate the first map in the series. Note and record the date and time of this map.
- Observe the location of the first low pressure center in the Seattle, Washington area on March 30, 2012.
- Record its location on the blank U.S. map by drawing a L on the blank map and circling it.
- Advance to the next map image, March 31, 2012. Note the location of the low, now located near northern Idaho. Record this new on your blank map.
- Advance to the 3rd map image. The low pressure is now over Montana. Again, record the location on your blank map.
- Repeat this procedure for the next several map images, following one storm as it travels across the country, and eventually heads out across the Atlantic Ocean.
Stop and Think
1. Which day (date) did the L pressure move off the Atlantic coast?
2. How many days did it take for the storm to travel across the country?
3. Given the distance the storm traveled as approximately 2700 miles (4350 kilometers), what was the average rate of travel of the storm? Express your answer in miles (or kilometers) per day.
DiscussTalking about the Weather
Some areas have weather patterns that are more variable than others. You may have heard the adage: "If you don't like the weather in Vermont (or some other place...), just wait five minutes." How fast does the weather change in your hometown or neighborhood?
Recall the regional climate drivers that you studied in Labs 3A and 3B. Which of these factors contributed to the movement of this storm system across the country? Choose a location on the storm track and use your knowledge to write out a script that could be used by a TV meteorologist to describe the weather patterns shown in the series of images. Share your weather story with your lab team or class.
Use weather data to discover climate patterns
When you have investigated these concepts, you will apply your skills by using the USHCN site to inform your answer to the question: "What will I wear to my cousin's wedding in May?"
When we think of weather we often only think of today, this week or this month. However, if you step back and look at a large collection of weather data it is possible to use the daily records to visualize the climate. The United States Historical Climatology Network (USHCN) archives many variables of weather and climate data, summarizing the data in both monthly and daily time frames, making many types of research possible.
The daily data recorded at these USHCN stations includes observations of: maximum and minimum temperature, precipitation amount, snowfall amount, and snow depth. Monthly data includes mean, maximum, and minimum temperature and total precipitation. Most data records extend through the most recent year (2011). For this exercise you will use the daily data.
The data you will use in this activity is available at the following website. Access the United States Historical Climatology Network (USHCN) website and begin your investigation.
- On the USHCN page select the Web Interface link to access data via a map of stations.
- Once on the map interface, use the drop-down menu to select your state and site of interest. All of the sites in the state will be listed, and displayed on the map.
- Use the zoom and pan tools, in the upper-left corner of the map, to zoom into your state and select a site to explore. Once you have selected a site, click on the balloon to learn more about the site.
Montana stations are displayed on the map in the image below.
- In the pop-up bubble, the name of the station, its latitude, longitude, and elevation are displayed. Click the words "Get Daily Data" to access the data for the site.
Jordan, Montana has been selected in the image below.
- On the data selection page, click the link titled Climate variable vs day of year to move down the list of possibilities.
- Select the climate variable that you wish to view, in this example choose Temperature mean for the year of your birth.
- Under the heading "Select a variable for a plot of variable vs day of year (annual)" choose the radio button next to Temperature mean.
- In the boxes next to the words "for the year (inclusive)" type in one year, such as your birth year, into both boxes. (This will select only one year's worth of data.)
In the example below, Temperature mean has been selected, the years are set to show data from 1905 through 2011. To select one years worth of data type the same year into both boxes.
- Once you have made your selections, click the Get the Plot button to view a graph of daily mean temperature for the year of your choice. Use a screen capture program to save a copy of this graph so that you can compare it to other graphs. Note: When you are done viewing the graph use the back button to return to the previous screen.
Montana Temperature Data (in degrees F) for the Year 1990.
- After you have investigated one year, select a 30-year range of data around your birth year. In other words, if your birth year was 1960, you would choose 1945-1975. How do you think this will change the appearance of the graph? Once you have set the parameters, and stated your hypothesis, click the Get the Plot button to see a graph of daily mean temperature for the selected years.
- Next, click the Reset Form button in order to see the available years of record for the station. Then re-select the Temperature mean button and click get the plot to graph all of the available data points for the station of your choice.
- Repeat this procedure, only choose the Precipitation variable this time.
- For more weather variables, such as wind speed and barometric pressure, access the Weather Underground historical data website. Again, input your city, and date range of choice in order to observe daily, weekly, monthly, or custom date range data outputs.
What new patterns emerge in the plotted data when you add more years to the graph?The pattern is still highly variable, but, in general, you can see that in this part of the United States, it is warmest in July and August and coldest in November, December, January and February. With this amount of data you can see that there is a lot more variation of temperatures in the winter months. (In other words, the data points are not clustered as closely in the winter.)
However, you can begin to see that there are patterns that emerge year after year, giving you a sense of "normal" weather which is known as climate.
Stop and Think4. How do the long-term graphs of weather data compare to the original (single year) graph? Which type of graph is a better representation of typical temperature and precipitation for a station?
5. Your cousin in Hastings, Nebraska (NE) has invited you to her outdoor wedding in early May. What will you wear? What is the likelihood that you will you need a sweater or jacket? Might it be over 100˚F; in which case you better bring shorts! Is it likely that it will it rain? Use the USHCN and Weather Underground sites to investigate historical Nebraska temperature and precipitation data in order to answer this question. Explain your clothing selection and your procedure for arriving at this decision.
- Use ImageJ to animate and measure the rate at which the fronts moved during the week of March 30 - April 6, 2012. The images can be downloaded from the zipped file below. Instructions for use of ImageJ can be found in the following EET chapter, Exploring and Animating GOES Images.
zipped maps for storm tracking exercise (Zip Archive 1.3MB Apr14 12)
- Download and analyze another set of weather maps from the National Weather Service.
- Research your local weather history for a period of time using the Weather Underground site.