SO441 Lab 1: Surface and upper-air data and analysis

Objectives. At the end of this lab, you will be able to:

-Familiarize yourself with web sites that show surface and upper-air data

-Interpret surface observations (decode the surface station plot, e.g.)

-Interpretupper-air observations (decode the upper-level station plot, e.g.)

-Hand analyze temperature, pressure, and upper-level height

-Identify important features on the hand-analyzed surface map (i.e., fronts, other boundaries, high/low pressure systems)

-Identify important features on the hand-analyzed upper-level map (i.e., troughs, ridges, vorticity centers)

-Interpret both hand analyses in a concise written discussion, identifying the important features at both the surface and upper levels and linking them together

General tasks / introduction.

1. Visit . Click on several of the cities to zoom to surface charts for a specific region of the U.S. Note the structure of these charts. They plot station models that quickly display important weather observations. If you do not remember how to interpret the station model (particularly how to interpret the pressure observation), you can visit the NOAA page at There are also many other pages on station model interpretation.

There are also many pages that interpret the upper-level station model. Here is a solid one from Univ of Illinois: Note that the dew point observation varies across sites: some plot actual dew point, and others plot dew point depression.

2. One of the most important repositories for weather data we will use in this class comes from Plymouth State University in Plymouth, New Hampshire. Their faculty and students have taken great care to create a reasonably user-friendly web interface to view archived weather data for the world over the last 50+ years. It is my experience that this kind of access to weather data is unparalleled anywhere else in the world. The home page of the Plymouth State Weather Center is Take 10 minutes to click around on the links. Pay especial attention to the “Make Your Own…” and “Archived Data” options.

Now under the Surface | “Make Your Own…” link, choose the “Recent” option. Spend 10-15 mins playing with this interface. Change the region, the variable, the time, the density, the scaling, the map size, and the time zone label, and see what results you get. If you know a certain station identifier (Annapolis is “KNAK”; Baltimore is “KBWI”; and Reagan National Airport in Washington is “KDCA”), you can center the map on that identifier.

Notice that you can create a surface map at the archived data site as well. You are encouraged to include weather maps in your briefings that come from this web site, especially if you are analyzing an event from the past.

Questions (100 pts)

The task for this lab will be for you to analyze the surface and upper-troposphere weather conditions occurring right now, today Thursday 25 January 2018. First, for the surface: on the Plymouth State Weather Center page (“recent”), create a chart of the surface station plots (in Fahrenheit) for the entire Contiguous US, with default density, 0.7 scaling, and 1024x768 map size. Create the chart valid at 1200 UTC (12z).

1a. (5 points) Find the surface station models for Owensboro, KY and for Baltimore, MD. Reproduce (draw) them here. Then, below your diagrams, write out (interpret) the content contained in each. Be sure to include all content presented.

1b. (5 pts) Visit and locate the METAR observations from 12z (usually 1154-1158z) for both Owensboro (KOWB) and Annapolis (KNAK). Write the full 12z METAR code below, and then decode it for each. Finally, do the METAR codes match the data for the station models in part (a) above?

2. (10 pts) Now let’s move to the 300 mb pressure surface. Back on the Plymouth State Weather Center page (“Upper Air | Make your own | Recent”), create a chart of the 300 mb surfacein decameters (Composite Plot (dm)) for the entire Contiguous US, with default density, 0.7 scaling, and 1024x768 map size. Create the chart valid again today at 1200 UTC (12z). Find the upper-level station models for Grand Junction, CO and for Pittsburgh, PA. Reproduce (copy) them below, then interpret them.

3. Print a copy of your surface and upper-level charts,in landscape orientation (you might copy the figure into PPT or word, stretch it to fill the page completely, then print. Click around in the printer window to figure out how to print in landscape). When you’re satisfied that your image looks good on the screen, print two copies of it. (Since there isn’t a printer in our classroom, Prof. Barrett will provide the charts. You can also download a copy of them from the course web site, if you need to use them later).

Surface. (30 points). Using your two printouts, hand analyze (1) Temperature,and (2) Sea Level Pressure (analyze each variable on a separate page – otherwise your analysis will become cluttered). Follow the conventions for isoplethingin the Lesson 1 and 2 Powerpoints. Focus on neatness, smoothness, and fidelity to the data. Identify centers of surface low and high pressure (place L and H symbols, respectively) on the MSLP analysis. Make a note of any sharp temperature gradients (and annotate your analysis with front symbols if you are confident!).

Upper-air. (30 pts). Using the one printout, hand analyze the 300-mb heights. Follow the conventions for isoplething in the course Powerpoints. The community standard for 300 mb is somewhat variable, but 9000 m is a required level, and heights are typically contoured every 120 m (every 12 dm) (although some sources contour every 60 m). Focus on neatness, smoothness, and fidelity to the data. Identify troughs and ridges by placing a dashed line (trough) and zig-zag line (ridge) along the axes of each.

3. (30 points) Using your two hand analyses, type a coherent weather discussion identifying the important features on the 12Z surface chart for 24Jan 2018. Your writeup discussion should highlight temperature and sea level pressure. You should focus mostly on answering the question “What?”, as opposed to “Why?” or “How?”. We will get to those questions later in the course! Be sure to use appropriate quantitative values and geographic key words. Instead of saying “there was warm air in the lower right of the page”, say “Surface air temperatures were between 55F and 70F all along the U.S. East and Gulf coasts, from Pennsylvania south to Florida and west to Texas.” The discussion should be about 1 page long, double-spaced.

Staple your written analysis to your two hand analyzed charts, with this Lab Activity page as a cover page.