Note: Prior to this activity, students spent about 20 minutes exploring the following website, which provided introductory information regarding how to read weather maps:
NOAA SciJinks – It’s All About Weather – How to Read a Weather Map: https://scijinks.gov/weather-map/
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We will break up participants into 4 groups, where each group will focus on one weather system “case study.” Here are the four cases listed below; all case study weather maps can be accessed using the link here: https://intothestorm.s3.amazonaws.com/story.html
- Record-Breaking Upper Midwest U.S. Extratropical Cyclone – 26 October 2010
- Alabama Tornado Outbreak – 27 April 2011
- Easter Sunday Severe Weather Outbreak – 12 April 2020
- Rocky Mountain “Bombogenesis” Event – 13 March 2019
For your extreme low-pressure system case provided, complete the following 4 parts, answering your questions within the “Weather Map Analysis Answers” module on Canvas (consider opening a separate web browser tab so that you can switch between this and the answer text box):
Part 1 – Air Flow Around Low and High-Pressure Systems
Watch the “Hand Twist” video from AMS if you have not already
2. Try out the hand technique for a low-pressure system on your weather map. After trying this yourself, what direction did your hand rotate? Did your hand rise upward or sink downward when you finished the hand motion?
3. Repeat the above but for the high-pressure system, you identified.
Now, let’s use the data on the surface weather map to confirm if the winds are consistent with your hand motions for each pressure system.
Consider the low-pressure system (identified with a red box). Submit the best answer for each question below based on your wind observations:
- Is there rotation of air around the low-pressure system center (yes or no)?
- Is the wind rotating clockwise or counterclockwise around the low pressure system?
- Is the air at the center of the low pressure system converging or diverging?
- Does this suggest the air at the center of the low pressure system is rising or sinking?
- Are the isobars (or the lines of constant pressure) packed together or spread out for the low pressure system?
Repeat the above but for the high-pressure system (identified with a blue box). Submit the best answer for each question below based on your wind observations:
- Is there rotation of air around the high-pressure system center (yes or no)?
- Is the wind rotating clockwise or counterclockwise around the high pressure system?
- Is the air at the center of the high pressure system converging or diverging?
- Does this suggest the air at the center of the high pressure system is rising or sinking?
- Are the isobars (or the lines of constant pressure) packed together or spread out for the high pressure system?
Part 2: Radar and Satellite Imagery
Now that you have vigorously analyzed your extreme weather event’s surface map, let’s take a look at the radar and satellite data around the same time as your map. This can be used to 1) confirm your observations about low and high pressure systems and 2) develop new insight about the distribution of clouds and precipitation within the vicinity of low and/or high pressure systems.
First, start with the satellite image provided. This image shows cloud coverage (the whiter or green/red colors) over the U.S.
- Do you observe any clouds within the vicinity of the low pressure system? If so, what do the clouds look like on the satellite image? Hint: use your surface weather map to remember where the center of the low is located geographically in the U.S.
- Repeat the previous question but for the high pressure system on your weather map.
Next, analyze the radar image provided. To interpret this image: green colors represent light precipitation, yellow and orange represents moderate precipitation and possibly thunderstorms, and red and pink represents heavy precipitation and sometimes strong to severe thunderstorms.
Given this information, answer the following:
- Do you observe any precipitation within the vicinity of the low pressure system? If so, how light or heavy is the precipitation, or does it vary?
- What relationship do you observe between where the cold and warm fronts are located with that of where precipitation is occurring near the low pressure system?
- Do you observe any precipitation within the vicinity of the high pressure system? If so, how light or heavy is the precipitation, or does it vary?
Part 3 – Storm Reports
The last image provided shows storm report damage from the event you have analyzed. Red dots refer to tornado reports, green dots refer to hail and blue dots refer to wind damage reports.
Based on your observations from the previous images, answer the following:
- Which system do the storm reports happen closest to: the low or high pressure system?
- Which front(s) does (do) the storm reports happen closest to, if any?
- Which storm damage hazard was reported the most: wind damage, hail or tornado?