DATASTREME SUPPLEMENTAL SUMMARY
To complement the Daily Summary for Wednesday, 14 November 2001
TRACKING WEATHER SYSTEMS
The low and high pressure systems of mid-latitude surface weather maps are
migratory. Often these systems appear to take preferred, seasonal tracks across
the country. As an exercise, we can track these systems over several days or a
week.
Movement of these systems can be monitored on a tracking
chart. Positions of systems from surface weather maps are plotted on
the tracking chart at regular intervals to give a picture of their progression.
WHAT IS NEEDED
Using a blank
US base map such as that found on the DataStreme Homepage, you can:
- Locate the centers of the lows (cyclones) and highs (anticyclones) on the
0Z and 12Z surface maps from the DataStreme homepage. You should select
only those well-defined cyclones or anticyclones that have at least one closed
isobar and that can be found twelve hours later. Plot the location of the
centers of cyclones and anticyclones at 12 hour intervals (00 and 12 Z) from
the surface analyses onto your base map. For clarity, you may want to use
separate base maps for cyclones and anticyclones.
- Mark the position of the pressure center (H or L) on the tracking chart
with a circle and neatly plot the time above that location.
- Connect the location circles for the same cyclone/anticyclone with a black
line.
As an additional feature, you could also inspect the upper air charts for
the same time interval. Often times, the surface weather systems are steered by
the mid tropospheric winds. Therefore, inspect the 500 mb analysis charts for
0Z and 12Z from the DataStreme homepage. Look at the direction of the
500 mb flow above the particular surface weather feature.
WHAT INFORMATION CAN BE DETERMINED
While you are monitoring the movement of weather systems, you may want to
consider and identify:
- In what direction(s) did the cyclones move? Did you detect any preferential
tracks? If so, where were these tracks located?
- In what direction(s) did the anticyclones move? Did you detect any
preferential tracks? If so, where were the tracks?
- How do these surface pressure features move with respect to the upper level
flow patterns?
- Did you find that any systems formed in the region during the interval? If
so, where did these systems appear?
- Did any systems decay? If so, where did they finally disappear?
- What happened when a system moving east from the Pacific approaches the
Western states? Could you track these systems across the mountains and into the
Plains states?
Return to the Wednesday Daily Summary
Return to DataStreme Homepage
URL: datastreme/learn/w_sup.html
Prepared by Edward J. Hopkins, Ph.D., email
hopkins@meteor.wisc.edu
© Copyright, 2001, The American Meteorological Society.