Demystifying the 500 mB Chart

with Lee Chesneau

September 7, from 1:00 p.m. to 4:00 p.m. $45

Register here.

Dive into a deeper discussion to further your understanding of this important tool for self-reliant marine weather forecasting & routing offshore & high seas, especially the Pacific Northwest boater. Specifically:

  • Identifying upper-level troughs and ridges as depicted on 500 mb charts.
  • How 500 mb controls sea-level surface low and high-pressure systems (e.g., influences as to where surface low and high-pressure weather systems originate, intensify, weaken, and move).
  • Discussion & illustration of what a weather pattern is, & how to identify & recognize the four (4) basic 500 mb flow patterns.
  • A discussion of how to develop a culture of routinely accessing both 500 mb and their companion at sea-level surface pressure charts, & annotating specific features that will allow one to clearly see their connected inter-relationships.
  • To introduce the A. B, C and D zones associated with a 500 mb chart

Seminar will take place at the Northwest Maritime Center, 431 Water Street, Port Townsend, WA 98368

Register here.

A little bit about Lee:

Lee Chesneau is a senior marine meteorologist and graduate from one of the elite universities that offer degrees in meteorology, the University of Wisconsin (Madison). His Bachelor of Science Degree in Meteorology was Lee’s ticket to a distinguished and extensive career with NOAA’s National Weather Service (NWS) & Satellite Service (NESDIS). Lee also served as a U.S. Navy civilian Ship Routing Officer (SRO), a “Route Analyst” for a major commercial ship routing company, and his first career started as a naval officer.

In addition, to being a highly seasoned and experienced professional marine meteorologist, he is an accomplished U.S. Coast Guard certified instructor for basic and advanced meteorology at continuing training institutions for professional mariners. He offers the same curriculum to educate and train commercial fishing and recreational seafarers on becoming self-reliant in their own marine weather knowledge and forecasting, strategic vessel routing, and prudent decision making. Lee is a speaker at numerous boat shows and symposia and has his own company: Lee Chesneau’s Marine Weather He can be reached by e-mail:


Northwest Maritime Center LogoWaggoner Cruising GuideThis course is being presented by the NW Maritime Center together with the Waggoner Cruising Guide at the Port Townsend Wooden Boat Festival just before the Festival’s formal opening. Arrive early for the Festival and stay on your boat or stay in one of the convenient hotels in Port Townsend.

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