Upper-Air Observations and Analysis

SO 254 Spring 2017

SO254 Lab 2 Upper-air observations and analysis

Objectives: - Become familiar with web sites that show upper-air observations - Interpret upper-air observations (decode the station plot, e.g.) - Hand analyze temperature and height at different levels - Identify important features on the hand-analyzed upper-air map (i.e., troughs, ridges, low- level fronts) - Interpret the hand analysis (written paragraphs) describing the country’s weather based on the hand analysis

General tasks / introduction

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 http://vortex.plymouth.edu/. Take 10 minutes to click around on the links. Pay especial attention to the “Make Your Own…” and “Archived Data” options.

Now under the Upper Air | “Make Your Own…” link, choose the “Recent” option. Spend 10-15 mins playing with this interface. Change the pressure level, region, the variable, the time, the scaling, and the map size, and see what results you get.

Notice that you can create an upper-air 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 upper-air weather conditions occurring right now, today Tuesday 31 January 2017. On the Plymouth State Weather Center page, hover over “upper air”, select “make your own”, and choose the “recent” option under the “plotted maps” product. Create a chart of the variable “composite plot” (decameters, dm) at 500 mb for the entire Contiguous US using 0.7 scaling and 1024x768 map size. Create the chart valid at 0000 UTC (00z).

1) (10 points) Find the 500 mb station models for Oklahoma City, OK (KOKC) and for Minneapolis, MN (KMPX) (those observation sites were chosen mainly because they are far apart and because they are usually easy to read on the map). Reproduce (draw) those two observations in the space below. Then, below your diagrams, write out (interpret) the content contained in each. Be sure to include all content presented.

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KOKC (500 mb) KMPX (500 mb)

Station model sketch

interpretation

2) (10 points) Once you’ve interpreted the 00Z observations at 500 mb for KOKC and KMPX, create a separate chart of the composite plot (decameters, dm) for 850 mb for the entire Contiguous US, with 0.7 scaling and 1024x768 map size. Create the chart valid at 0000 UTC (00z). Now find, draw, and interpret the 850 mb station models for Oklahoma City, OK and for Minneapolis, MN.

KOKC (850 mb) KMPX (850 mb)

Station model sketch

interpretation

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3) (5 points) Using the values from the station models you sketched on the previous page, use the space below to determine the thickness between the 850 mb and 500 mb pressure levels at each station, and discuss briefly whether your results conform to your expectation based on what you know about thickness.

4) Now, print two copies of each chart (500 mb and 850 mb) 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). Don’t print until you’re satisfied that your image looks good on the screen (e.g., in print preview) and that it’s zoomed to fill the entire page without cutting off any data.

(50 points) Using your four printouts, hand analyze (1) Height, and (2) Temperature, each on a separate print-out, at 500 mb and then at 850 mb. Follow the conventions for isoplething as outlined in the lecture slides. Focus on neatness, smoothness, and fidelity to the data.

5) (25 points) Using your four hand analyses, type a coherent weather discussion that highlights the important features that you observe in your plots and draw connections where you can between the various data. For one, you should discuss whether patterns seem to agree between the two pressure levels and whether relationships between temperature and height at a particular pressure level appear to conform with the relationships we’ve discussed in class. 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. For example, instead of saying “there was warm air in the lower right of the page”, you might say “Upper air temperatures at 500 mb were between -15C and -30C all along the U.S. East and Gulf coasts, from Pennsylvania south to Florida and west to Texas.” The discussion should be about 2 pages long, double-spaced.

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