Some Rules of Contouring
- All contours eventually connect
because they form closed curves, but can end at map borders (they connect off
of the map space).
- Contours should be smooth curves,
except at fronts, outflow boundaries, surrface troughs, drylines, where
contours should be kinked AWAY from low pressure.
- Contours should be labeled at
convenient locations and at ends near the periphery of charts.
- Contours should be drawn at
conventional intervals and at conventional initial values (i.e., on surface chart,
4 mb intervals (2 mb subsynoptic) starting at 1000 mb etc., or 564 dm at 6 dm intervals at 500 mb (check contour intervals given).
- Areas of low and high pressures
(heights) should be labeled with red "L" (or "Low") and
blue "H" (or "High"), respectively.
- Winds should be in either
geostrophic/gradient balance or "friction" (boundary layer) wind
balance with contours depending upon analysis level.
- Disturbances with
wavelength less than about 200 km or so should NOT appear on contour patterns
for 700 mb and above. This is because the radiosonde network is too coarse to resolve
disturbances of this scale. Such disturbances appearing on computer analyzed
charts are usually spurious and should be ignored.
- Contour patterns should be
consistent with previous charts.
- When analyzing charts, a rough
draft should be done on acetate first. No erasures or sloppiness on final
drafts is tolerated. After you are satisfied with your acetate analysis, then
you can transfer to final copy using a light table.