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Weather Forecasting for Mariners: the 500 millibar Chart – Webinar

On Demand

The 500 millibar chart is a powerful forecasting tool readily available at no cost to boaters. Learn how to use it and you’ll see why it has earned a special place in the mariner’s toolkit.

The webinar is led by an expert meteorologist, Joe Sienkiewicz, a Branch Chief at the National Weather Service’s Ocean Prediction. Center.

The 500 mb Chart shows the:

  • speed and direction of the winds aloft that steer large scale storms,
  • trough and ridge patters which enhance and inhibit surface storm development.

You’ll learn which weather patterns on the chart are associated with the likelihood of particular surface conditions. Examples include:

  • long and short waves with storm generation; 
  • zonal and meridional air flow with fair and foul weather; 
  • blocking ridges and cut-off lows with persisting weather.

You’ll also learn about the special 5640 line because surface storm tracks tend to parallel  it 300 to 600 nautical miles to the north. North of the line the winds tend to be stronger and south of the line, weaker.

An America's Boating Club® Webinar.
Originally broadcast: 9/23/2014
Duration: 1 hr 0 m

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Dan Johnson

This is a good webinar and the speakers did a very good job of explaining the use of the 500mb charts. I would have given a better rating if there wasn't so much back ground noise during the webinar. The background noise (paper shuffling, people talking, dog barking) became very distracting - so my rating is more in the quality of the webinar not the content.