San Francisco State University

Department of Earth & Climate Sciences

Name ______________________________________

ERTH 260: Physical Processes of the Atmosphere


In-class Exercise 1: The Surface Weather Map (100 points)

Due Wednesday 31 January 2018

The term "weather map" apples to any horizontal chart drawn at a constant level (i.e, sealevel, 6000 m, etc.) upon which some aspect of "weather" is depicted. Usually, the weather map shows a synopsis of weather observations, often analyzed by a meteorologist or a computer, at a given time over certain areas.

Surface Weather Map

Today the class is going to work with the surface map for 1200 UTC 22 Jan 2017, in which a major storm was affecting the California. This weather map was obtained from the Department of Earth & Climate Sciences Weather Graphics and Simulation Lab (WGSL). We'll also obtain comparable map for today, 1200 UTC 24 Jan 2018.

A. Obtaining the surface weather map for 1200 UTC 24 January 2018 from the Weather Graphics and Simulation Lab (WGSL) (40 pts)

B. Discussion of Weather Map for Major Storm from Last Season, that of 1200 UTC 22 January 2017.

We'll discuss the surface weather map for you would have obtained had you executed sfcplot 17012212. The difference is that when you print the chart, it will appear as black print with a white background. By the way, the teaching approach of using something happening of interest currently to investigate thematic material that one would need to understand it is called "inquiry-based learning."


  1. What is the date and time of the map in Pacific Standard Time? ( 5 pts)

    January 22, 2017, 4AM PST

  2. What would you say is the distribution in space (how many miles or km apart) of the weather stations depicted? (Please answer in a complete sentence or sentences)( 5 pts)

    The stations are not perfectly evenly spaced, but they appear to be, on average, about 200 miles (300 km) apart.

  3. Given what we discussed in class on Wednesday, why do you think only these stations are shown?(Please answer in a complete sentence or sentences)( 5 pts)

    These stations were selected because most are in major metropolitan areas, or at least provide representative conditions for an area. The spacing was chosen to make the map readable (reduce crowding).

  4. The information for the weather stations is plotted on the basis of what is known as the station model. We will discuss the information plotted routinely on weather maps via the station model out of sequence to our theoretical and conceptual discussions of the various variables (for example, temperature and dew point temperature, but we will skip pressure for now). After we get through that discussion, answer the following questions:

    1. What are the coldest and warmest temperatures you see on the chart?( 10 pts)

      The coldest temperature is 11 F (at Helena, MT), and the warmest temperature is 76F (at Miami FL).

    2. What are the strongest winds you see on the map?( 5 pts)

      The strongest winds are 25 mph at El Paso, TX.

    3. Examine the information for San Francisco. Provide the following information: (20 pts)
      1. Temperature ___53F___________

      2. Dew Point Temperature______47F___________

      3. Wind direction and speed_____South 20 mph_________

      4. Present Weather___Moderate rain________________

      5. State of the sky___Cloudy_______________
    4. A satellite image (called the visible satellite image, as explained in class) for 1700 UTC on 1/22/17 is given here. Comment on the degree to which the weather observation of cloud cover shown on the surface weather map captures the degree to which the nation was covered with clouds. (10 pts)

      The satellite image shows the country basicallly covered with clouds except in the souhtern Great Plains into Texas, andin southern Florida. This is corroborated by the surface cloud cover observations that basically have coverage at 100% (overcast) in the cloudy retions and clear skies or only a few clouds in the southern Great Plains and southern Florida. One exception appears to be at Boise, Idaho, which is reporting clear skies, though the satellite image shows cloud cover there.