This course will integrate interactive lecture & hands on exercises over the intensive 3-day period beginning with the 101 building blocks of weather basics (necessary because of the nature of a physical science that is 100 percent knowledge based), then moving onto the diverse core of marine oriented weather products from graphics, alpha-numeric text, to voice broadcasts.
There is the need to view different scales of weather from global to local, where in between is the more dominate synoptic scale (e.g.,the north Pacific Ocean whether regional or full ocean, where the time frame extends from days or weeks) & its influences on more local marine weather conditions of the Pacific NW (Salish Sea) including the coastal waters ranging from SE Alaska through the US West coast including Vancouver Island where the time frame extends from a few hours to a day. Another way of summarizing; the synoptic scale weather that include weather systems such as low & high pressure, & their features such as fronts, troughs, & ridges that span from to days to more than a weeks will dictate weather conditions (clouds, propitiation & fog, & wind) from what one sees from a boats wheelhouse that last from hours or a day, that can be repeated over & over again.
Whether one is a novice, experienced boater, or racer who sails or cruises the Inland waters (Salish Sea), the Pacific Northwest coast (BC, WA, OR, CA) as well as further offshore into the high seas waters of the North Pacific Ocean (this can apply to any other ocean, including the southern ocean), there is only one way to strategize the marine environment: understand it.
After an introduction & overview of the three-day course, specific topics will cover:
- A discussion of some important definitions; weather (WX), climate, & the atmosphere.
- A brief discussion of the different layers of the atmosphere, focusing on the layer where most weather occurs.
- A discussion of the role of the sun & radiation in generating the land & sea temperature difference, the primary cause of both sea &land breezes, both from large global scale to local or microscale.
- A discussion of moisture in the atmosphere & it’s unique role in cloud formation & other visibility restricting conditions such as fog or precipitation.
- An overview of the importance of atmospheric stability & its significance to clouds & overall weather conditions.
- The different cloud groups & types, & what they mean to a mariner.
- A discussion of basic concepts of pressure & wind, & how they work to develop & deliver common low & high pressure systems at sea-level (surface pressure).
- We then will look at scales of WX systems from global, synoptic, meso to microscale; & how the cruising sailor needs to understand & prioritize them.
- A discussion of air masses & how do they relate to synoptic scale WX systems, especially the depiction of associated features on the surface at sea-level WX charts (e.g. the various surface fronts to be discussed subsequently).
- Significant time will be spent discussing synoptic scale WX systems, specifically the dominant middle latitude (30N/S-60N/S) migratory low & high pressure systems & their associated features from cold, warm, occluded, & stationary fronts, to troughs & ridges, shear lines, & cols.
- Wind & swell waves (sea state conditions) definitions & concepts
- Discussion of the U.S. National Weather Service (NWS) wind & wave analyses & forecast products & how to integrate them with their companion NWS surface pressure analyses & forecasts charts.
- Factoring geographic & local weather effects from surface pressure & wind & wave products.
- A discussion of local marine weather of the Pacific Northwest (Salish Sea), especially noting the gap winds that enhance wind speed conditions between them. There will be an overview of marine weather forecast services from the Vancouver Weather Service Office of Environment Canada & the U.S. NWS Forecast Office (NWSFO) in Seattle.
- Overview of international marine forecast charts, necessary to integrate with cruising to other ocean areas not covered by the NWS.
- Concepts of upper air charts, focusing on 500 Mb.
- Concepts of weather routing as it relates to 500 Mb charts.
- A detailed discussion of the climatology based pilot charts & how to interpret them for potential long range voyage planning.
- Overview of the hierarchy of marine weather analysis, forecasting & vessel routing decision making.
Hands On Exercises:
- From the Bowditch Tables, determine dew point temperature from wet bul temperature exercise& determining relative humidity exercise;
- Determine true wind from geostrophic wind exercise;
- Identifying air masses on synoptic surface pressure charts;
- Determine the correct valid date & time of the principle synoptic scale surface pressure low & high pressure systems, & the specific identification of synoptic scale systems’ features exercise;
- Identifying the various symbols on the charts, & the specific weather conditions they will produce;
- Utilizing the Bowditch Wind, Wave, Period & Fetch Tables, determine likely significant wave heights, period, time, & required fetch necessary for these conditions;
- Identifying 500 mb flow patterns;
- How to route a vessel via 500 mb flow patterns;
- Long- range planning route for the North & South Pacific Oceans utilizing pilot charts;
- After reviewing the validity of the most current forecasts, the follow up to this will be a voyage exercises for the North Pacific Oceans (including portions of the South Pacific) from Anacortes to Cape Flattery to San Francisco to Hawaii onto Fiji & American Samoa.
Instructor: Lee Chesneau
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