Case 23: 8 - 11 November 1998
Lab Exercises using Garp Exploring Cloud and Precipitation
Structure
Note: I plan to enhance these labs with example imagery pertaining
to each set of questions
Garp Instructions
- Make a loop of the GOES-8 IR satellite imagery every 6 hours from 00 UTC 10 Nov through 00 UTC 11 Nov.
- Zoom in on the area of interest and overlay the 500 mb heights and sea level pressure from the eta model for the same times using the F000 and F006 times.
- After looking at questions, feel free to look at the visible imagery or imagery at different resolutions, etc.
Questions
1. Do the cloud patterns evident in these images relate to the upper level flow and surface patterns in a similar fashion as the ideal relationships shown in figure 2 at the end of this write-up?
2. What are the nature of the clouds in the vicinity of the cold front (stratiform? convective?)? How does the cloud pattern evolve in the vicinity of the deepening low pressure center?
Garp Instructions
- Clear Screen
- Plot the lowest level reflectivity from the radar station Springfield, Missouri for the period 0530 UTC 10 Nov through 0730 UTC 10 Nov.
- You may want to consult maps, or look at other plots (such as the satellite imagery or surface fields) to get a large scale perspective.
- After looking at the radar loop, replot the reflectivity for the times 0600 UTC and 0700 UTC.
- Overlay the surface observations for the same two times.
Questions
3. What is the red line in the radar loop? How do the surface observations change across this line (temperature, precipitation, wind).
Main Points
- The overall cloud structure take on the comma shape in many extratropical cyclones.
- The structure of clouds and precipitation occur on a spectrum of scales and can include large-scale stratiform and embedded convective clouds in many extratropical cyclones.
- The cold front is often marked by a narrow convective band called
the narrow cold-frontal rain band.
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