An Introduction to the 500 Mb Chart

12:00 PM


Lee Chesneau

An Introduction to the 500 Mb Chart

Seminar will discuss what professional marine meteorologists (& mariners) who forecast & route vessels refer to as the “holy grail of weather forecasting & routing”, such as 500 mb is. Specifically: The breakdown components of the upper air 500 mb chart, such as the lowest elevation markings of L’s, & H’s, which also includes fixed altitude contour lines (called iso-heights), winds, & trough axes. Examples of upper-air 500 mb charts & their companion surface pressure charts revealing their direct inter-relationship. Finally, there will be an important overview of why these upper air charts are such an important resource for boaters in terms of practical at sea-level weather analysis & forecast applications while at sea level via “Rules of Thumb”. This seminar is an important prerequisite to the prepaid 2.5-hour “500 Mb Chart Workshop” which will be conducted later from 2:15-3:15 PM


Lee Chesneau is a senior marine meteorologist, lecturer, & author. He is a graduate from the University of Wisconsin (Madison) where he earned a B.S. Degree in Meteorology.  Lee had a distinguished & extensive career with NOAA’s National Weather Service (NWS) & Satellite Service. He also served as naval officer in the U.S. Navy, a “Route Analyst” for a commercial weather & ship routing company. Today, Lee is an accomplished U.S. Coast Guard certified instructor for basic and advanced meteorology at number of continuing training institutions for professional mariners. He offers the same curriculum to educate & train recreational boaters on becoming self-reliant in their own marine weather knowledge for application in marine weather forecasting & strategic vessel routing.  See his webpage  He can be reached by e-mail:

Room 1

  Vancouver Boat Show