Written with AI assistance and may contain mistakes. Verify against the official Transport Canada publications before relying on anything here.

Reading contours, temperature and winds on ANAL charts

Reading ANAL charts (TC AIM MET 11.1):

Chart	Contour spacing	Temperature source
850 hPa	60 m (6 decametres)	Analyzed dashed lines, 5°C intervals
700 hPa	60 m (6 decametres)	Analyzed dashed lines, 5°C intervals
500 hPa	60 m (6 decametres)	Station plot, upper-left number
250 hPa	120 m	Station plot, upper-left number

Height: solid contours, labelled in decametres (10s of m).
- 540 on 500 hPa = 5,400 m.
- 1020 on 250 hPa = 10,200 m.
Wind direction: generally parallel to contours, not across. Station arrows give actual direction.
Wind speed: inversely proportional to contour spacing: close = strong, wide = light. Station arrows give actual speed.
Isotachs (250 hPa only): dashed lines of equal wind speed, computer-analyzed, 30-kt intervals starting at 60 kt.
Smoothing: computer-analyzed parameters are smoothed to some extent; contours approximate, not exact station values.

Trap: temperature comes off a contour only on 850/700 hPa; on 500/250 hPa read the station plot corner.

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