Isobars

19 clues
Front lines?
Some map lines
Weather map lines
Forecaster's lines
Map pressure lines
Some weather lines
Weather map features
Lines on certain maps
Meteorological lines.
Pressure lines on map
Lines on weather maps
Weather map connectors
Lines on a weather map
High and low indicators
Lines from Willard Scott
Meteorological map lines
Indicators of equal pressure
Lines of equal barometric pressure
They're found between highs and lows