Possible Clues:

• Some weather lines
• Lines showing equal pressure
• Pressure lines from one such to pubs
• One thus excludes lines under pressure
• Pressure points are all the same to us
• 15 is strong when they are close
• Weather map connectors
• Pressure on lines one Mayday when ringing lawyers
• On weather map, air's so turbulent around Birkenhead
• Air boss (anag.)